1 /* Expands front end tree to back end RTL for GCC
2 Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997,
3 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
23 /* This file handles the generation of rtl code from tree structure
24 above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
25 The functions whose names start with `expand_' are called by the
26 expander to generate RTL instructions for various kinds of constructs. */
30 #include "coretypes.h"
34 #include "hard-reg-set.h"
40 #include "insn-config.h"
48 #include "langhooks.h"
54 /* Functions and data structures for expanding case statements. */
56 /* Case label structure, used to hold info on labels within case
57 statements. We handle "range" labels; for a single-value label
58 as in C, the high and low limits are the same.
60 We start with a vector of case nodes sorted in ascending order, and
61 the default label as the last element in the vector. Before expanding
62 to RTL, we transform this vector into a list linked via the RIGHT
63 fields in the case_node struct. Nodes with higher case values are
66 Switch statements can be output in three forms. A branch table is
67 used if there are more than a few labels and the labels are dense
68 within the range between the smallest and largest case value. If a
69 branch table is used, no further manipulations are done with the case
72 The alternative to the use of a branch table is to generate a series
73 of compare and jump insns. When that is done, we use the LEFT, RIGHT,
74 and PARENT fields to hold a binary tree. Initially the tree is
75 totally unbalanced, with everything on the right. We balance the tree
76 with nodes on the left having lower case values than the parent
77 and nodes on the right having higher values. We then output the tree
80 For very small, suitable switch statements, we can generate a series
81 of simple bit test and branches instead. */
83 struct case_node GTY(())
85 struct case_node *left; /* Left son in binary tree */
86 struct case_node *right; /* Right son in binary tree; also node chain */
87 struct case_node *parent; /* Parent of node in binary tree */
88 tree low; /* Lowest index value for this label */
89 tree high; /* Highest index value for this label */
90 tree code_label; /* Label to jump to when node matches */
93 typedef struct case_node case_node;
94 typedef struct case_node *case_node_ptr;
96 /* These are used by estimate_case_costs and balance_case_nodes. */
98 /* This must be a signed type, and non-ANSI compilers lack signed char. */
99 static short cost_table_[129];
100 static int use_cost_table;
101 static int cost_table_initialized;
103 /* Special care is needed because we allow -1, but TREE_INT_CST_LOW
105 #define COST_TABLE(I) cost_table_[(unsigned HOST_WIDE_INT) ((I) + 1)]
107 static int n_occurrences (int, const char *);
108 static bool tree_conflicts_with_clobbers_p (tree, HARD_REG_SET *);
109 static void expand_nl_goto_receiver (void);
110 static bool check_operand_nalternatives (tree, tree);
111 static bool check_unique_operand_names (tree, tree);
112 static char *resolve_operand_name_1 (char *, tree, tree);
113 static void expand_null_return_1 (void);
114 static void expand_value_return (rtx);
115 static void do_jump_if_equal (rtx, rtx, rtx, int);
116 static int estimate_case_costs (case_node_ptr);
117 static bool lshift_cheap_p (void);
118 static int case_bit_test_cmp (const void *, const void *);
119 static void emit_case_bit_tests (tree, tree, tree, tree, case_node_ptr, rtx);
120 static void balance_case_nodes (case_node_ptr *, case_node_ptr);
121 static int node_has_low_bound (case_node_ptr, tree);
122 static int node_has_high_bound (case_node_ptr, tree);
123 static int node_is_bounded (case_node_ptr, tree);
124 static void emit_case_nodes (rtx, case_node_ptr, rtx, tree);
125 static struct case_node *add_case_node (struct case_node *, tree,
129 /* Return the rtx-label that corresponds to a LABEL_DECL,
130 creating it if necessary. */
133 label_rtx (tree label)
135 gcc_assert (TREE_CODE (label) == LABEL_DECL);
137 if (!DECL_RTL_SET_P (label))
139 rtx r = gen_label_rtx ();
140 SET_DECL_RTL (label, r);
141 if (FORCED_LABEL (label) || DECL_NONLOCAL (label))
142 LABEL_PRESERVE_P (r) = 1;
145 return DECL_RTL (label);
148 /* As above, but also put it on the forced-reference list of the
149 function that contains it. */
151 force_label_rtx (tree label)
153 rtx ref = label_rtx (label);
154 tree function = decl_function_context (label);
157 gcc_assert (function);
159 if (function != current_function_decl)
160 p = find_function_data (function);
164 p->expr->x_forced_labels = gen_rtx_EXPR_LIST (VOIDmode, ref,
165 p->expr->x_forced_labels);
169 /* Add an unconditional jump to LABEL as the next sequential instruction. */
172 emit_jump (rtx label)
174 do_pending_stack_adjust ();
175 emit_jump_insn (gen_jump (label));
179 /* Emit code to jump to the address
180 specified by the pointer expression EXP. */
183 expand_computed_goto (tree exp)
185 rtx x = expand_expr (exp, NULL_RTX, VOIDmode, 0);
187 x = convert_memory_address (Pmode, x);
189 do_pending_stack_adjust ();
190 emit_indirect_jump (x);
193 /* Handle goto statements and the labels that they can go to. */
195 /* Specify the location in the RTL code of a label LABEL,
196 which is a LABEL_DECL tree node.
198 This is used for the kind of label that the user can jump to with a
199 goto statement, and for alternatives of a switch or case statement.
200 RTL labels generated for loops and conditionals don't go through here;
201 they are generated directly at the RTL level, by other functions below.
203 Note that this has nothing to do with defining label *names*.
204 Languages vary in how they do that and what that even means. */
207 expand_label (tree label)
209 rtx label_r = label_rtx (label);
211 do_pending_stack_adjust ();
212 emit_label (label_r);
213 if (DECL_NAME (label))
214 LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));
216 if (DECL_NONLOCAL (label))
218 expand_nl_goto_receiver ();
219 nonlocal_goto_handler_labels
220 = gen_rtx_EXPR_LIST (VOIDmode, label_r,
221 nonlocal_goto_handler_labels);
224 if (FORCED_LABEL (label))
225 forced_labels = gen_rtx_EXPR_LIST (VOIDmode, label_r, forced_labels);
227 if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
228 maybe_set_first_label_num (label_r);
231 /* Generate RTL code for a `goto' statement with target label LABEL.
232 LABEL should be a LABEL_DECL tree node that was or will later be
233 defined with `expand_label'. */
236 expand_goto (tree label)
238 #ifdef ENABLE_CHECKING
239 /* Check for a nonlocal goto to a containing function. Should have
240 gotten translated to __builtin_nonlocal_goto. */
241 tree context = decl_function_context (label);
242 gcc_assert (!context || context == current_function_decl);
245 emit_jump (label_rtx (label));
248 /* Return the number of times character C occurs in string S. */
250 n_occurrences (int c, const char *s)
258 /* Generate RTL for an asm statement (explicit assembler code).
259 STRING is a STRING_CST node containing the assembler code text,
260 or an ADDR_EXPR containing a STRING_CST. VOL nonzero means the
261 insn is volatile; don't optimize it. */
264 expand_asm (tree string, int vol)
268 if (TREE_CODE (string) == ADDR_EXPR)
269 string = TREE_OPERAND (string, 0);
271 body = gen_rtx_ASM_INPUT (VOIDmode,
272 ggc_strdup (TREE_STRING_POINTER (string)));
274 MEM_VOLATILE_P (body) = vol;
279 /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the
280 OPERAND_NUMth output operand, indexed from zero. There are NINPUTS
281 inputs and NOUTPUTS outputs to this extended-asm. Upon return,
282 *ALLOWS_MEM will be TRUE iff the constraint allows the use of a
283 memory operand. Similarly, *ALLOWS_REG will be TRUE iff the
284 constraint allows the use of a register operand. And, *IS_INOUT
285 will be true if the operand is read-write, i.e., if it is used as
286 an input as well as an output. If *CONSTRAINT_P is not in
287 canonical form, it will be made canonical. (Note that `+' will be
288 replaced with `=' as part of this process.)
290 Returns TRUE if all went well; FALSE if an error occurred. */
293 parse_output_constraint (const char **constraint_p, int operand_num,
294 int ninputs, int noutputs, bool *allows_mem,
295 bool *allows_reg, bool *is_inout)
297 const char *constraint = *constraint_p;
300 /* Assume the constraint doesn't allow the use of either a register
305 /* Allow the `=' or `+' to not be at the beginning of the string,
306 since it wasn't explicitly documented that way, and there is a
307 large body of code that puts it last. Swap the character to
308 the front, so as not to uglify any place else. */
309 p = strchr (constraint, '=');
311 p = strchr (constraint, '+');
313 /* If the string doesn't contain an `=', issue an error
317 error ("output operand constraint lacks %<=%>");
321 /* If the constraint begins with `+', then the operand is both read
322 from and written to. */
323 *is_inout = (*p == '+');
325 /* Canonicalize the output constraint so that it begins with `='. */
326 if (p != constraint || *is_inout)
329 size_t c_len = strlen (constraint);
332 warning (0, "output constraint %qc for operand %d "
333 "is not at the beginning",
336 /* Make a copy of the constraint. */
337 buf = alloca (c_len + 1);
338 strcpy (buf, constraint);
339 /* Swap the first character and the `=' or `+'. */
340 buf[p - constraint] = buf[0];
341 /* Make sure the first character is an `='. (Until we do this,
342 it might be a `+'.) */
344 /* Replace the constraint with the canonicalized string. */
345 *constraint_p = ggc_alloc_string (buf, c_len);
346 constraint = *constraint_p;
349 /* Loop through the constraint string. */
350 for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p))
355 error ("operand constraint contains incorrectly positioned "
360 if (operand_num + 1 == ninputs + noutputs)
362 error ("%<%%%> constraint used with last operand");
367 case 'V': case 'm': case 'o':
371 case '?': case '!': case '*': case '&': case '#':
372 case 'E': case 'F': case 'G': case 'H':
373 case 's': case 'i': case 'n':
374 case 'I': case 'J': case 'K': case 'L': case 'M':
375 case 'N': case 'O': case 'P': case ',':
378 case '0': case '1': case '2': case '3': case '4':
379 case '5': case '6': case '7': case '8': case '9':
381 error ("matching constraint not valid in output operand");
385 /* ??? Before flow, auto inc/dec insns are not supposed to exist,
386 excepting those that expand_call created. So match memory
403 if (REG_CLASS_FROM_CONSTRAINT (*p, p) != NO_REGS)
405 #ifdef EXTRA_CONSTRAINT_STR
406 else if (EXTRA_ADDRESS_CONSTRAINT (*p, p))
408 else if (EXTRA_MEMORY_CONSTRAINT (*p, p))
412 /* Otherwise we can't assume anything about the nature of
413 the constraint except that it isn't purely registers.
414 Treat it like "g" and hope for the best. */
425 /* Similar, but for input constraints. */
428 parse_input_constraint (const char **constraint_p, int input_num,
429 int ninputs, int noutputs, int ninout,
430 const char * const * constraints,
431 bool *allows_mem, bool *allows_reg)
433 const char *constraint = *constraint_p;
434 const char *orig_constraint = constraint;
435 size_t c_len = strlen (constraint);
437 bool saw_match = false;
439 /* Assume the constraint doesn't allow the use of either
440 a register or memory. */
444 /* Make sure constraint has neither `=', `+', nor '&'. */
446 for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
447 switch (constraint[j])
449 case '+': case '=': case '&':
450 if (constraint == orig_constraint)
452 error ("input operand constraint contains %qc", constraint[j]);
458 if (constraint == orig_constraint
459 && input_num + 1 == ninputs - ninout)
461 error ("%<%%%> constraint used with last operand");
466 case 'V': case 'm': case 'o':
471 case '?': case '!': case '*': case '#':
472 case 'E': case 'F': case 'G': case 'H':
473 case 's': case 'i': case 'n':
474 case 'I': case 'J': case 'K': case 'L': case 'M':
475 case 'N': case 'O': case 'P': case ',':
478 /* Whether or not a numeric constraint allows a register is
479 decided by the matching constraint, and so there is no need
480 to do anything special with them. We must handle them in
481 the default case, so that we don't unnecessarily force
482 operands to memory. */
483 case '0': case '1': case '2': case '3': case '4':
484 case '5': case '6': case '7': case '8': case '9':
491 match = strtoul (constraint + j, &end, 10);
492 if (match >= (unsigned long) noutputs)
494 error ("matching constraint references invalid operand number");
498 /* Try and find the real constraint for this dup. Only do this
499 if the matching constraint is the only alternative. */
501 && (j == 0 || (j == 1 && constraint[0] == '%')))
503 constraint = constraints[match];
504 *constraint_p = constraint;
505 c_len = strlen (constraint);
507 /* ??? At the end of the loop, we will skip the first part of
508 the matched constraint. This assumes not only that the
509 other constraint is an output constraint, but also that
510 the '=' or '+' come first. */
514 j = end - constraint;
515 /* Anticipate increment at end of loop. */
530 if (! ISALPHA (constraint[j]))
532 error ("invalid punctuation %qc in constraint", constraint[j]);
535 if (REG_CLASS_FROM_CONSTRAINT (constraint[j], constraint + j)
538 #ifdef EXTRA_CONSTRAINT_STR
539 else if (EXTRA_ADDRESS_CONSTRAINT (constraint[j], constraint + j))
541 else if (EXTRA_MEMORY_CONSTRAINT (constraint[j], constraint + j))
545 /* Otherwise we can't assume anything about the nature of
546 the constraint except that it isn't purely registers.
547 Treat it like "g" and hope for the best. */
555 if (saw_match && !*allows_reg)
556 warning (0, "matching constraint does not allow a register");
561 /* Return DECL iff there's an overlap between *REGS and DECL, where DECL
562 can be an asm-declared register. Called via walk_tree. */
565 decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED,
569 const HARD_REG_SET *regs = data;
571 if (TREE_CODE (decl) == VAR_DECL)
573 if (DECL_HARD_REGISTER (decl)
574 && REG_P (DECL_RTL (decl))
575 && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
577 rtx reg = DECL_RTL (decl);
580 for (regno = REGNO (reg);
582 + hard_regno_nregs[REGNO (reg)][GET_MODE (reg)]);
584 if (TEST_HARD_REG_BIT (*regs, regno))
589 else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL)
594 /* If there is an overlap between *REGS and DECL, return the first overlap
597 tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs)
599 return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL);
602 /* Check for overlap between registers marked in CLOBBERED_REGS and
603 anything inappropriate in T. Emit error and return the register
604 variable definition for error, NULL_TREE for ok. */
607 tree_conflicts_with_clobbers_p (tree t, HARD_REG_SET *clobbered_regs)
609 /* Conflicts between asm-declared register variables and the clobber
610 list are not allowed. */
611 tree overlap = tree_overlaps_hard_reg_set (t, clobbered_regs);
615 error ("asm-specifier for variable %qs conflicts with asm clobber list",
616 IDENTIFIER_POINTER (DECL_NAME (overlap)));
618 /* Reset registerness to stop multiple errors emitted for a single
620 DECL_REGISTER (overlap) = 0;
627 /* Generate RTL for an asm statement with arguments.
628 STRING is the instruction template.
629 OUTPUTS is a list of output arguments (lvalues); INPUTS a list of inputs.
630 Each output or input has an expression in the TREE_VALUE and
631 and a tree list in TREE_PURPOSE which in turn contains a constraint
632 name in TREE_VALUE (or NULL_TREE) and a constraint string
634 CLOBBERS is a list of STRING_CST nodes each naming a hard register
635 that is clobbered by this insn.
637 Not all kinds of lvalue that may appear in OUTPUTS can be stored directly.
638 Some elements of OUTPUTS may be replaced with trees representing temporary
639 values. The caller should copy those temporary values to the originally
642 VOL nonzero means the insn is volatile; don't optimize it. */
645 expand_asm_operands (tree string, tree outputs, tree inputs,
646 tree clobbers, int vol, location_t locus)
648 rtvec argvec, constraintvec;
650 int ninputs = list_length (inputs);
651 int noutputs = list_length (outputs);
654 HARD_REG_SET clobbered_regs;
655 int clobber_conflict_found = 0;
659 /* Vector of RTX's of evaluated output operands. */
660 rtx *output_rtx = alloca (noutputs * sizeof (rtx));
661 int *inout_opnum = alloca (noutputs * sizeof (int));
662 rtx *real_output_rtx = alloca (noutputs * sizeof (rtx));
663 enum machine_mode *inout_mode
664 = alloca (noutputs * sizeof (enum machine_mode));
665 const char **constraints
666 = alloca ((noutputs + ninputs) * sizeof (const char *));
667 int old_generating_concat_p = generating_concat_p;
669 /* An ASM with no outputs needs to be treated as volatile, for now. */
673 if (! check_operand_nalternatives (outputs, inputs))
676 string = resolve_asm_operand_names (string, outputs, inputs);
678 /* Collect constraints. */
680 for (t = outputs; t ; t = TREE_CHAIN (t), i++)
681 constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
682 for (t = inputs; t ; t = TREE_CHAIN (t), i++)
683 constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
685 /* Sometimes we wish to automatically clobber registers across an asm.
686 Case in point is when the i386 backend moved from cc0 to a hard reg --
687 maintaining source-level compatibility means automatically clobbering
688 the flags register. */
689 clobbers = targetm.md_asm_clobbers (outputs, inputs, clobbers);
691 /* Count the number of meaningful clobbered registers, ignoring what
692 we would ignore later. */
694 CLEAR_HARD_REG_SET (clobbered_regs);
695 for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
697 const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail));
699 i = decode_reg_name (regname);
700 if (i >= 0 || i == -4)
703 error ("unknown register name %qs in %<asm%>", regname);
705 /* Mark clobbered registers. */
708 /* Clobbering the PIC register is an error. */
709 if (i == (int) PIC_OFFSET_TABLE_REGNUM)
711 error ("PIC register %qs clobbered in %<asm%>", regname);
715 SET_HARD_REG_BIT (clobbered_regs, i);
719 /* First pass over inputs and outputs checks validity and sets
720 mark_addressable if needed. */
723 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
725 tree val = TREE_VALUE (tail);
726 tree type = TREE_TYPE (val);
727 const char *constraint;
732 /* If there's an erroneous arg, emit no insn. */
733 if (type == error_mark_node)
736 /* Try to parse the output constraint. If that fails, there's
737 no point in going further. */
738 constraint = constraints[i];
739 if (!parse_output_constraint (&constraint, i, ninputs, noutputs,
740 &allows_mem, &allows_reg, &is_inout))
747 && REG_P (DECL_RTL (val))
748 && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type))))
749 lang_hooks.mark_addressable (val);
756 if (ninputs + noutputs > MAX_RECOG_OPERANDS)
758 error ("more than %d operands in %<asm%>", MAX_RECOG_OPERANDS);
762 for (i = 0, tail = inputs; tail; i++, tail = TREE_CHAIN (tail))
764 bool allows_reg, allows_mem;
765 const char *constraint;
767 /* If there's an erroneous arg, emit no insn, because the ASM_INPUT
768 would get VOIDmode and that could cause a crash in reload. */
769 if (TREE_TYPE (TREE_VALUE (tail)) == error_mark_node)
772 constraint = constraints[i + noutputs];
773 if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
774 constraints, &allows_mem, &allows_reg))
777 if (! allows_reg && allows_mem)
778 lang_hooks.mark_addressable (TREE_VALUE (tail));
781 /* Second pass evaluates arguments. */
784 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
786 tree val = TREE_VALUE (tail);
787 tree type = TREE_TYPE (val);
794 ok = parse_output_constraint (&constraints[i], i, ninputs,
795 noutputs, &allows_mem, &allows_reg,
799 /* If an output operand is not a decl or indirect ref and our constraint
800 allows a register, make a temporary to act as an intermediate.
801 Make the asm insn write into that, then our caller will copy it to
802 the real output operand. Likewise for promoted variables. */
804 generating_concat_p = 0;
806 real_output_rtx[i] = NULL_RTX;
807 if ((TREE_CODE (val) == INDIRECT_REF
810 && (allows_mem || REG_P (DECL_RTL (val)))
811 && ! (REG_P (DECL_RTL (val))
812 && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type)))
816 op = expand_expr (val, NULL_RTX, VOIDmode, EXPAND_WRITE);
818 op = validize_mem (op);
820 if (! allows_reg && !MEM_P (op))
821 error ("output number %d not directly addressable", i);
822 if ((! allows_mem && MEM_P (op))
823 || GET_CODE (op) == CONCAT)
825 real_output_rtx[i] = op;
826 op = gen_reg_rtx (GET_MODE (op));
828 emit_move_insn (op, real_output_rtx[i]);
833 op = assign_temp (type, 0, 0, 1);
834 op = validize_mem (op);
835 TREE_VALUE (tail) = make_tree (type, op);
839 generating_concat_p = old_generating_concat_p;
843 inout_mode[ninout] = TYPE_MODE (type);
844 inout_opnum[ninout++] = i;
847 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs))
848 clobber_conflict_found = 1;
851 /* Make vectors for the expression-rtx, constraint strings,
852 and named operands. */
854 argvec = rtvec_alloc (ninputs);
855 constraintvec = rtvec_alloc (ninputs);
857 body = gen_rtx_ASM_OPERANDS ((noutputs == 0 ? VOIDmode
858 : GET_MODE (output_rtx[0])),
859 ggc_strdup (TREE_STRING_POINTER (string)),
860 empty_string, 0, argvec, constraintvec,
863 MEM_VOLATILE_P (body) = vol;
865 /* Eval the inputs and put them into ARGVEC.
866 Put their constraints into ASM_INPUTs and store in CONSTRAINTS. */
868 for (i = 0, tail = inputs; tail; tail = TREE_CHAIN (tail), ++i)
870 bool allows_reg, allows_mem;
871 const char *constraint;
876 constraint = constraints[i + noutputs];
877 ok = parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
878 constraints, &allows_mem, &allows_reg);
881 generating_concat_p = 0;
883 val = TREE_VALUE (tail);
884 type = TREE_TYPE (val);
885 op = expand_expr (val, NULL_RTX, VOIDmode,
886 (allows_mem && !allows_reg
887 ? EXPAND_MEMORY : EXPAND_NORMAL));
889 /* Never pass a CONCAT to an ASM. */
890 if (GET_CODE (op) == CONCAT)
891 op = force_reg (GET_MODE (op), op);
893 op = validize_mem (op);
895 if (asm_operand_ok (op, constraint) <= 0)
897 if (allows_reg && TYPE_MODE (type) != BLKmode)
898 op = force_reg (TYPE_MODE (type), op);
899 else if (!allows_mem)
900 warning (0, "asm operand %d probably doesn%'t match constraints",
904 /* We won't recognize either volatile memory or memory
905 with a queued address as available a memory_operand
906 at this point. Ignore it: clearly this *is* a memory. */
910 warning (0, "use of memory input without lvalue in "
911 "asm operand %d is deprecated", i + noutputs);
915 rtx mem = force_const_mem (TYPE_MODE (type), op);
917 op = validize_mem (mem);
919 op = force_reg (TYPE_MODE (type), op);
922 || GET_CODE (op) == SUBREG
923 || GET_CODE (op) == CONCAT)
925 tree qual_type = build_qualified_type (type,
928 rtx memloc = assign_temp (qual_type, 1, 1, 1);
929 memloc = validize_mem (memloc);
930 emit_move_insn (memloc, op);
936 generating_concat_p = old_generating_concat_p;
937 ASM_OPERANDS_INPUT (body, i) = op;
939 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, i)
940 = gen_rtx_ASM_INPUT (TYPE_MODE (type),
941 ggc_strdup (constraints[i + noutputs]));
943 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs))
944 clobber_conflict_found = 1;
947 /* Protect all the operands from the queue now that they have all been
950 generating_concat_p = 0;
952 /* For in-out operands, copy output rtx to input rtx. */
953 for (i = 0; i < ninout; i++)
955 int j = inout_opnum[i];
958 ASM_OPERANDS_INPUT (body, ninputs - ninout + i)
961 sprintf (buffer, "%d", j);
962 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, ninputs - ninout + i)
963 = gen_rtx_ASM_INPUT (inout_mode[i], ggc_strdup (buffer));
966 generating_concat_p = old_generating_concat_p;
968 /* Now, for each output, construct an rtx
969 (set OUTPUT (asm_operands INSN OUTPUTCONSTRAINT OUTPUTNUMBER
970 ARGVEC CONSTRAINTS OPNAMES))
971 If there is more than one, put them inside a PARALLEL. */
973 if (noutputs == 1 && nclobbers == 0)
975 ASM_OPERANDS_OUTPUT_CONSTRAINT (body) = ggc_strdup (constraints[0]);
976 emit_insn (gen_rtx_SET (VOIDmode, output_rtx[0], body));
979 else if (noutputs == 0 && nclobbers == 0)
981 /* No output operands: put in a raw ASM_OPERANDS rtx. */
993 body = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (num + nclobbers));
995 /* For each output operand, store a SET. */
996 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
999 = gen_rtx_SET (VOIDmode,
1001 gen_rtx_ASM_OPERANDS
1002 (GET_MODE (output_rtx[i]),
1003 ggc_strdup (TREE_STRING_POINTER (string)),
1004 ggc_strdup (constraints[i]),
1005 i, argvec, constraintvec, locus));
1007 MEM_VOLATILE_P (SET_SRC (XVECEXP (body, 0, i))) = vol;
1010 /* If there are no outputs (but there are some clobbers)
1011 store the bare ASM_OPERANDS into the PARALLEL. */
1014 XVECEXP (body, 0, i++) = obody;
1016 /* Store (clobber REG) for each clobbered register specified. */
1018 for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
1020 const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail));
1021 int j = decode_reg_name (regname);
1026 if (j == -3) /* `cc', which is not a register */
1029 if (j == -4) /* `memory', don't cache memory across asm */
1031 XVECEXP (body, 0, i++)
1032 = gen_rtx_CLOBBER (VOIDmode,
1035 gen_rtx_SCRATCH (VOIDmode)));
1039 /* Ignore unknown register, error already signaled. */
1043 /* Use QImode since that's guaranteed to clobber just one reg. */
1044 clobbered_reg = gen_rtx_REG (QImode, j);
1046 /* Do sanity check for overlap between clobbers and respectively
1047 input and outputs that hasn't been handled. Such overlap
1048 should have been detected and reported above. */
1049 if (!clobber_conflict_found)
1053 /* We test the old body (obody) contents to avoid tripping
1054 over the under-construction body. */
1055 for (opno = 0; opno < noutputs; opno++)
1056 if (reg_overlap_mentioned_p (clobbered_reg, output_rtx[opno]))
1057 internal_error ("asm clobber conflict with output operand");
1059 for (opno = 0; opno < ninputs - ninout; opno++)
1060 if (reg_overlap_mentioned_p (clobbered_reg,
1061 ASM_OPERANDS_INPUT (obody, opno)))
1062 internal_error ("asm clobber conflict with input operand");
1065 XVECEXP (body, 0, i++)
1066 = gen_rtx_CLOBBER (VOIDmode, clobbered_reg);
1072 /* For any outputs that needed reloading into registers, spill them
1073 back to where they belong. */
1074 for (i = 0; i < noutputs; ++i)
1075 if (real_output_rtx[i])
1076 emit_move_insn (real_output_rtx[i], output_rtx[i]);
1082 expand_asm_expr (tree exp)
1088 if (ASM_INPUT_P (exp))
1090 expand_asm (ASM_STRING (exp), ASM_VOLATILE_P (exp));
1094 outputs = ASM_OUTPUTS (exp);
1095 noutputs = list_length (outputs);
1096 /* o[I] is the place that output number I should be written. */
1097 o = (tree *) alloca (noutputs * sizeof (tree));
1099 /* Record the contents of OUTPUTS before it is modified. */
1100 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1101 o[i] = TREE_VALUE (tail);
1103 /* Generate the ASM_OPERANDS insn; store into the TREE_VALUEs of
1104 OUTPUTS some trees for where the values were actually stored. */
1105 expand_asm_operands (ASM_STRING (exp), outputs, ASM_INPUTS (exp),
1106 ASM_CLOBBERS (exp), ASM_VOLATILE_P (exp),
1109 /* Copy all the intermediate outputs into the specified outputs. */
1110 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1112 if (o[i] != TREE_VALUE (tail))
1114 expand_assignment (o[i], TREE_VALUE (tail));
1117 /* Restore the original value so that it's correct the next
1118 time we expand this function. */
1119 TREE_VALUE (tail) = o[i];
1124 /* A subroutine of expand_asm_operands. Check that all operands have
1125 the same number of alternatives. Return true if so. */
1128 check_operand_nalternatives (tree outputs, tree inputs)
1130 if (outputs || inputs)
1132 tree tmp = TREE_PURPOSE (outputs ? outputs : inputs);
1134 = n_occurrences (',', TREE_STRING_POINTER (TREE_VALUE (tmp)));
1137 if (nalternatives + 1 > MAX_RECOG_ALTERNATIVES)
1139 error ("too many alternatives in %<asm%>");
1146 const char *constraint
1147 = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tmp)));
1149 if (n_occurrences (',', constraint) != nalternatives)
1151 error ("operand constraints for %<asm%> differ "
1152 "in number of alternatives");
1156 if (TREE_CHAIN (tmp))
1157 tmp = TREE_CHAIN (tmp);
1159 tmp = next, next = 0;
1166 /* A subroutine of expand_asm_operands. Check that all operand names
1167 are unique. Return true if so. We rely on the fact that these names
1168 are identifiers, and so have been canonicalized by get_identifier,
1169 so all we need are pointer comparisons. */
1172 check_unique_operand_names (tree outputs, tree inputs)
1176 for (i = outputs; i ; i = TREE_CHAIN (i))
1178 tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
1182 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
1183 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
1187 for (i = inputs; i ; i = TREE_CHAIN (i))
1189 tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
1193 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
1194 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
1196 for (j = outputs; j ; j = TREE_CHAIN (j))
1197 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
1204 error ("duplicate asm operand name %qs",
1205 TREE_STRING_POINTER (TREE_PURPOSE (TREE_PURPOSE (i))));
1209 /* A subroutine of expand_asm_operands. Resolve the names of the operands
1210 in *POUTPUTS and *PINPUTS to numbers, and replace the name expansions in
1211 STRING and in the constraints to those numbers. */
1214 resolve_asm_operand_names (tree string, tree outputs, tree inputs)
1221 check_unique_operand_names (outputs, inputs);
1223 /* Substitute [<name>] in input constraint strings. There should be no
1224 named operands in output constraints. */
1225 for (t = inputs; t ; t = TREE_CHAIN (t))
1227 c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
1228 if (strchr (c, '[') != NULL)
1230 p = buffer = xstrdup (c);
1231 while ((p = strchr (p, '[')) != NULL)
1232 p = resolve_operand_name_1 (p, outputs, inputs);
1233 TREE_VALUE (TREE_PURPOSE (t))
1234 = build_string (strlen (buffer), buffer);
1239 /* Now check for any needed substitutions in the template. */
1240 c = TREE_STRING_POINTER (string);
1241 while ((c = strchr (c, '%')) != NULL)
1245 else if (ISALPHA (c[1]) && c[2] == '[')
1256 /* OK, we need to make a copy so we can perform the substitutions.
1257 Assume that we will not need extra space--we get to remove '['
1258 and ']', which means we cannot have a problem until we have more
1259 than 999 operands. */
1260 buffer = xstrdup (TREE_STRING_POINTER (string));
1261 p = buffer + (c - TREE_STRING_POINTER (string));
1263 while ((p = strchr (p, '%')) != NULL)
1267 else if (ISALPHA (p[1]) && p[2] == '[')
1275 p = resolve_operand_name_1 (p, outputs, inputs);
1278 string = build_string (strlen (buffer), buffer);
1285 /* A subroutine of resolve_operand_names. P points to the '[' for a
1286 potential named operand of the form [<name>]. In place, replace
1287 the name and brackets with a number. Return a pointer to the
1288 balance of the string after substitution. */
1291 resolve_operand_name_1 (char *p, tree outputs, tree inputs)
1298 /* Collect the operand name. */
1299 q = strchr (p, ']');
1302 error ("missing close brace for named operand");
1303 return strchr (p, '\0');
1307 /* Resolve the name to a number. */
1308 for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
1310 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
1313 const char *c = TREE_STRING_POINTER (name);
1314 if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
1318 for (t = inputs; t ; t = TREE_CHAIN (t), op++)
1320 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
1323 const char *c = TREE_STRING_POINTER (name);
1324 if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
1330 error ("undefined named operand %qs", p + 1);
1334 /* Replace the name with the number. Unfortunately, not all libraries
1335 get the return value of sprintf correct, so search for the end of the
1336 generated string by hand. */
1337 sprintf (p, "%d", op);
1338 p = strchr (p, '\0');
1340 /* Verify the no extra buffer space assumption. */
1341 gcc_assert (p <= q);
1343 /* Shift the rest of the buffer down to fill the gap. */
1344 memmove (p, q + 1, strlen (q + 1) + 1);
1349 /* Generate RTL to evaluate the expression EXP. */
1352 expand_expr_stmt (tree exp)
1357 value = expand_expr (exp, const0_rtx, VOIDmode, 0);
1358 type = TREE_TYPE (exp);
1360 /* If all we do is reference a volatile value in memory,
1361 copy it to a register to be sure it is actually touched. */
1362 if (value && MEM_P (value) && TREE_THIS_VOLATILE (exp))
1364 if (TYPE_MODE (type) == VOIDmode)
1366 else if (TYPE_MODE (type) != BLKmode)
1367 value = copy_to_reg (value);
1370 rtx lab = gen_label_rtx ();
1372 /* Compare the value with itself to reference it. */
1373 emit_cmp_and_jump_insns (value, value, EQ,
1374 expand_expr (TYPE_SIZE (type),
1375 NULL_RTX, VOIDmode, 0),
1381 /* Free any temporaries used to evaluate this expression. */
1385 /* Warn if EXP contains any computations whose results are not used.
1386 Return 1 if a warning is printed; 0 otherwise. LOCUS is the
1387 (potential) location of the expression. */
1390 warn_if_unused_value (tree exp, location_t locus)
1393 if (TREE_USED (exp) || TREE_NO_WARNING (exp))
1396 /* Don't warn about void constructs. This includes casting to void,
1397 void function calls, and statement expressions with a final cast
1399 if (VOID_TYPE_P (TREE_TYPE (exp)))
1402 if (EXPR_HAS_LOCATION (exp))
1403 locus = EXPR_LOCATION (exp);
1405 switch (TREE_CODE (exp))
1407 case PREINCREMENT_EXPR:
1408 case POSTINCREMENT_EXPR:
1409 case PREDECREMENT_EXPR:
1410 case POSTDECREMENT_EXPR:
1415 case TRY_CATCH_EXPR:
1416 case WITH_CLEANUP_EXPR:
1421 /* For a binding, warn if no side effect within it. */
1422 exp = BIND_EXPR_BODY (exp);
1426 exp = TREE_OPERAND (exp, 0);
1429 case TRUTH_ORIF_EXPR:
1430 case TRUTH_ANDIF_EXPR:
1431 /* In && or ||, warn if 2nd operand has no side effect. */
1432 exp = TREE_OPERAND (exp, 1);
1436 if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus))
1438 /* Let people do `(foo (), 0)' without a warning. */
1439 if (TREE_CONSTANT (TREE_OPERAND (exp, 1)))
1441 exp = TREE_OPERAND (exp, 1);
1445 /* If this is an expression with side effects, don't warn; this
1446 case commonly appears in macro expansions. */
1447 if (TREE_SIDE_EFFECTS (exp))
1452 /* Don't warn about automatic dereferencing of references, since
1453 the user cannot control it. */
1454 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE)
1456 exp = TREE_OPERAND (exp, 0);
1462 /* Referencing a volatile value is a side effect, so don't warn. */
1463 if ((DECL_P (exp) || REFERENCE_CLASS_P (exp))
1464 && TREE_THIS_VOLATILE (exp))
1467 /* If this is an expression which has no operands, there is no value
1468 to be unused. There are no such language-independent codes,
1469 but front ends may define such. */
1470 if (EXPRESSION_CLASS_P (exp) && TREE_CODE_LENGTH (TREE_CODE (exp)) == 0)
1474 warning (0, "%Hvalue computed is not used", &locus);
1480 /* Generate RTL to return from the current function, with no value.
1481 (That is, we do not do anything about returning any value.) */
1484 expand_null_return (void)
1486 /* If this function was declared to return a value, but we
1487 didn't, clobber the return registers so that they are not
1488 propagated live to the rest of the function. */
1489 clobber_return_register ();
1491 expand_null_return_1 ();
1494 /* Generate RTL to return directly from the current function.
1495 (That is, we bypass any return value.) */
1498 expand_naked_return (void)
1502 clear_pending_stack_adjust ();
1503 do_pending_stack_adjust ();
1505 end_label = naked_return_label;
1507 end_label = naked_return_label = gen_label_rtx ();
1509 emit_jump (end_label);
1512 /* Generate RTL to return from the current function, with value VAL. */
1515 expand_value_return (rtx val)
1517 /* Copy the value to the return location
1518 unless it's already there. */
1520 rtx return_reg = DECL_RTL (DECL_RESULT (current_function_decl));
1521 if (return_reg != val)
1523 tree type = TREE_TYPE (DECL_RESULT (current_function_decl));
1524 if (targetm.calls.promote_function_return (TREE_TYPE (current_function_decl)))
1526 int unsignedp = TYPE_UNSIGNED (type);
1527 enum machine_mode old_mode
1528 = DECL_MODE (DECL_RESULT (current_function_decl));
1529 enum machine_mode mode
1530 = promote_mode (type, old_mode, &unsignedp, 1);
1532 if (mode != old_mode)
1533 val = convert_modes (mode, old_mode, val, unsignedp);
1535 if (GET_CODE (return_reg) == PARALLEL)
1536 emit_group_load (return_reg, val, type, int_size_in_bytes (type));
1538 emit_move_insn (return_reg, val);
1541 expand_null_return_1 ();
1544 /* Output a return with no value. */
1547 expand_null_return_1 (void)
1549 clear_pending_stack_adjust ();
1550 do_pending_stack_adjust ();
1551 emit_jump (return_label);
1554 /* Generate RTL to evaluate the expression RETVAL and return it
1555 from the current function. */
1558 expand_return (tree retval)
1564 /* If function wants no value, give it none. */
1565 if (TREE_CODE (TREE_TYPE (TREE_TYPE (current_function_decl))) == VOID_TYPE)
1567 expand_expr (retval, NULL_RTX, VOIDmode, 0);
1568 expand_null_return ();
1572 if (retval == error_mark_node)
1574 /* Treat this like a return of no value from a function that
1576 expand_null_return ();
1579 else if ((TREE_CODE (retval) == MODIFY_EXPR
1580 || TREE_CODE (retval) == INIT_EXPR)
1581 && TREE_CODE (TREE_OPERAND (retval, 0)) == RESULT_DECL)
1582 retval_rhs = TREE_OPERAND (retval, 1);
1584 retval_rhs = retval;
1586 result_rtl = DECL_RTL (DECL_RESULT (current_function_decl));
1588 /* If we are returning the RESULT_DECL, then the value has already
1589 been stored into it, so we don't have to do anything special. */
1590 if (TREE_CODE (retval_rhs) == RESULT_DECL)
1591 expand_value_return (result_rtl);
1593 /* If the result is an aggregate that is being returned in one (or more)
1594 registers, load the registers here. The compiler currently can't handle
1595 copying a BLKmode value into registers. We could put this code in a
1596 more general area (for use by everyone instead of just function
1597 call/return), but until this feature is generally usable it is kept here
1598 (and in expand_call). */
1600 else if (retval_rhs != 0
1601 && TYPE_MODE (TREE_TYPE (retval_rhs)) == BLKmode
1602 && REG_P (result_rtl))
1605 unsigned HOST_WIDE_INT bitpos, xbitpos;
1606 unsigned HOST_WIDE_INT padding_correction = 0;
1607 unsigned HOST_WIDE_INT bytes
1608 = int_size_in_bytes (TREE_TYPE (retval_rhs));
1609 int n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
1610 unsigned int bitsize
1611 = MIN (TYPE_ALIGN (TREE_TYPE (retval_rhs)), BITS_PER_WORD);
1612 rtx *result_pseudos = alloca (sizeof (rtx) * n_regs);
1613 rtx result_reg, src = NULL_RTX, dst = NULL_RTX;
1614 rtx result_val = expand_expr (retval_rhs, NULL_RTX, VOIDmode, 0);
1615 enum machine_mode tmpmode, result_reg_mode;
1619 expand_null_return ();
1623 /* If the structure doesn't take up a whole number of words, see
1624 whether the register value should be padded on the left or on
1625 the right. Set PADDING_CORRECTION to the number of padding
1626 bits needed on the left side.
1628 In most ABIs, the structure will be returned at the least end of
1629 the register, which translates to right padding on little-endian
1630 targets and left padding on big-endian targets. The opposite
1631 holds if the structure is returned at the most significant
1632 end of the register. */
1633 if (bytes % UNITS_PER_WORD != 0
1634 && (targetm.calls.return_in_msb (TREE_TYPE (retval_rhs))
1636 : BYTES_BIG_ENDIAN))
1637 padding_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD)
1640 /* Copy the structure BITSIZE bits at a time. */
1641 for (bitpos = 0, xbitpos = padding_correction;
1642 bitpos < bytes * BITS_PER_UNIT;
1643 bitpos += bitsize, xbitpos += bitsize)
1645 /* We need a new destination pseudo each time xbitpos is
1646 on a word boundary and when xbitpos == padding_correction
1647 (the first time through). */
1648 if (xbitpos % BITS_PER_WORD == 0
1649 || xbitpos == padding_correction)
1651 /* Generate an appropriate register. */
1652 dst = gen_reg_rtx (word_mode);
1653 result_pseudos[xbitpos / BITS_PER_WORD] = dst;
1655 /* Clear the destination before we move anything into it. */
1656 emit_move_insn (dst, CONST0_RTX (GET_MODE (dst)));
1659 /* We need a new source operand each time bitpos is on a word
1661 if (bitpos % BITS_PER_WORD == 0)
1662 src = operand_subword_force (result_val,
1663 bitpos / BITS_PER_WORD,
1666 /* Use bitpos for the source extraction (left justified) and
1667 xbitpos for the destination store (right justified). */
1668 store_bit_field (dst, bitsize, xbitpos % BITS_PER_WORD, word_mode,
1669 extract_bit_field (src, bitsize,
1670 bitpos % BITS_PER_WORD, 1,
1671 NULL_RTX, word_mode, word_mode));
1674 tmpmode = GET_MODE (result_rtl);
1675 if (tmpmode == BLKmode)
1677 /* Find the smallest integer mode large enough to hold the
1678 entire structure and use that mode instead of BLKmode
1679 on the USE insn for the return register. */
1680 for (tmpmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
1681 tmpmode != VOIDmode;
1682 tmpmode = GET_MODE_WIDER_MODE (tmpmode))
1683 /* Have we found a large enough mode? */
1684 if (GET_MODE_SIZE (tmpmode) >= bytes)
1687 /* A suitable mode should have been found. */
1688 gcc_assert (tmpmode != VOIDmode);
1690 PUT_MODE (result_rtl, tmpmode);
1693 if (GET_MODE_SIZE (tmpmode) < GET_MODE_SIZE (word_mode))
1694 result_reg_mode = word_mode;
1696 result_reg_mode = tmpmode;
1697 result_reg = gen_reg_rtx (result_reg_mode);
1699 for (i = 0; i < n_regs; i++)
1700 emit_move_insn (operand_subword (result_reg, i, 0, result_reg_mode),
1703 if (tmpmode != result_reg_mode)
1704 result_reg = gen_lowpart (tmpmode, result_reg);
1706 expand_value_return (result_reg);
1708 else if (retval_rhs != 0
1709 && !VOID_TYPE_P (TREE_TYPE (retval_rhs))
1710 && (REG_P (result_rtl)
1711 || (GET_CODE (result_rtl) == PARALLEL)))
1713 /* Calculate the return value into a temporary (usually a pseudo
1715 tree ot = TREE_TYPE (DECL_RESULT (current_function_decl));
1716 tree nt = build_qualified_type (ot, TYPE_QUALS (ot) | TYPE_QUAL_CONST);
1718 val = assign_temp (nt, 0, 0, 1);
1719 val = expand_expr (retval_rhs, val, GET_MODE (val), 0);
1720 val = force_not_mem (val);
1721 /* Return the calculated value. */
1722 expand_value_return (val);
1726 /* No hard reg used; calculate value into hard return reg. */
1727 expand_expr (retval, const0_rtx, VOIDmode, 0);
1728 expand_value_return (result_rtl);
1732 /* Given a pointer to a BLOCK node return nonzero if (and only if) the node
1733 in question represents the outermost pair of curly braces (i.e. the "body
1734 block") of a function or method.
1736 For any BLOCK node representing a "body block" of a function or method, the
1737 BLOCK_SUPERCONTEXT of the node will point to another BLOCK node which
1738 represents the outermost (function) scope for the function or method (i.e.
1739 the one which includes the formal parameters). The BLOCK_SUPERCONTEXT of
1740 *that* node in turn will point to the relevant FUNCTION_DECL node. */
1743 is_body_block (tree stmt)
1745 if (lang_hooks.no_body_blocks)
1748 if (TREE_CODE (stmt) == BLOCK)
1750 tree parent = BLOCK_SUPERCONTEXT (stmt);
1752 if (parent && TREE_CODE (parent) == BLOCK)
1754 tree grandparent = BLOCK_SUPERCONTEXT (parent);
1756 if (grandparent && TREE_CODE (grandparent) == FUNCTION_DECL)
1764 /* Emit code to restore vital registers at the beginning of a nonlocal goto
1767 expand_nl_goto_receiver (void)
1769 /* Clobber the FP when we get here, so we have to make sure it's
1770 marked as used by this function. */
1771 emit_insn (gen_rtx_USE (VOIDmode, hard_frame_pointer_rtx));
1773 /* Mark the static chain as clobbered here so life information
1774 doesn't get messed up for it. */
1775 emit_insn (gen_rtx_CLOBBER (VOIDmode, static_chain_rtx));
1777 #ifdef HAVE_nonlocal_goto
1778 if (! HAVE_nonlocal_goto)
1780 /* First adjust our frame pointer to its actual value. It was
1781 previously set to the start of the virtual area corresponding to
1782 the stacked variables when we branched here and now needs to be
1783 adjusted to the actual hardware fp value.
1785 Assignments are to virtual registers are converted by
1786 instantiate_virtual_regs into the corresponding assignment
1787 to the underlying register (fp in this case) that makes
1788 the original assignment true.
1789 So the following insn will actually be
1790 decrementing fp by STARTING_FRAME_OFFSET. */
1791 emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx);
1793 #if ARG_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1794 if (fixed_regs[ARG_POINTER_REGNUM])
1796 #ifdef ELIMINABLE_REGS
1797 /* If the argument pointer can be eliminated in favor of the
1798 frame pointer, we don't need to restore it. We assume here
1799 that if such an elimination is present, it can always be used.
1800 This is the case on all known machines; if we don't make this
1801 assumption, we do unnecessary saving on many machines. */
1802 static const struct elims {const int from, to;} elim_regs[] = ELIMINABLE_REGS;
1805 for (i = 0; i < ARRAY_SIZE (elim_regs); i++)
1806 if (elim_regs[i].from == ARG_POINTER_REGNUM
1807 && elim_regs[i].to == HARD_FRAME_POINTER_REGNUM)
1810 if (i == ARRAY_SIZE (elim_regs))
1813 /* Now restore our arg pointer from the address at which it
1814 was saved in our stack frame. */
1815 emit_move_insn (virtual_incoming_args_rtx,
1816 copy_to_reg (get_arg_pointer_save_area (cfun)));
1821 #ifdef HAVE_nonlocal_goto_receiver
1822 if (HAVE_nonlocal_goto_receiver)
1823 emit_insn (gen_nonlocal_goto_receiver ());
1826 /* @@@ This is a kludge. Not all machine descriptions define a blockage
1827 insn, but we must not allow the code we just generated to be reordered
1828 by scheduling. Specifically, the update of the frame pointer must
1829 happen immediately, not later. So emit an ASM_INPUT to act as blockage
1831 emit_insn (gen_rtx_ASM_INPUT (VOIDmode, ""));
1834 /* Generate RTL for the automatic variable declaration DECL.
1835 (Other kinds of declarations are simply ignored if seen here.) */
1838 expand_decl (tree decl)
1842 type = TREE_TYPE (decl);
1844 /* For a CONST_DECL, set mode, alignment, and sizes from those of the
1845 type in case this node is used in a reference. */
1846 if (TREE_CODE (decl) == CONST_DECL)
1848 DECL_MODE (decl) = TYPE_MODE (type);
1849 DECL_ALIGN (decl) = TYPE_ALIGN (type);
1850 DECL_SIZE (decl) = TYPE_SIZE (type);
1851 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
1855 /* Otherwise, only automatic variables need any expansion done. Static and
1856 external variables, and external functions, will be handled by
1857 `assemble_variable' (called from finish_decl). TYPE_DECL requires
1858 nothing. PARM_DECLs are handled in `assign_parms'. */
1859 if (TREE_CODE (decl) != VAR_DECL)
1862 if (TREE_STATIC (decl) || DECL_EXTERNAL (decl))
1865 /* Create the RTL representation for the variable. */
1867 if (type == error_mark_node)
1868 SET_DECL_RTL (decl, gen_rtx_MEM (BLKmode, const0_rtx));
1870 else if (DECL_SIZE (decl) == 0)
1871 /* Variable with incomplete type. */
1874 if (DECL_INITIAL (decl) == 0)
1875 /* Error message was already done; now avoid a crash. */
1876 x = gen_rtx_MEM (BLKmode, const0_rtx);
1878 /* An initializer is going to decide the size of this array.
1879 Until we know the size, represent its address with a reg. */
1880 x = gen_rtx_MEM (BLKmode, gen_reg_rtx (Pmode));
1882 set_mem_attributes (x, decl, 1);
1883 SET_DECL_RTL (decl, x);
1885 else if (use_register_for_decl (decl))
1887 /* Automatic variable that can go in a register. */
1888 int unsignedp = TYPE_UNSIGNED (type);
1889 enum machine_mode reg_mode
1890 = promote_mode (type, DECL_MODE (decl), &unsignedp, 0);
1892 SET_DECL_RTL (decl, gen_reg_rtx (reg_mode));
1894 /* Note if the object is a user variable. */
1895 if (!DECL_ARTIFICIAL (decl))
1897 mark_user_reg (DECL_RTL (decl));
1899 /* Trust user variables which have a pointer type to really
1900 be pointers. Do not trust compiler generated temporaries
1901 as our type system is totally busted as it relates to
1902 pointer arithmetic which translates into lots of compiler
1903 generated objects with pointer types, but which are not really
1905 if (POINTER_TYPE_P (type))
1906 mark_reg_pointer (DECL_RTL (decl),
1907 TYPE_ALIGN (TREE_TYPE (TREE_TYPE (decl))));
1911 else if (TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST
1912 && ! (flag_stack_check && ! STACK_CHECK_BUILTIN
1913 && 0 < compare_tree_int (DECL_SIZE_UNIT (decl),
1914 STACK_CHECK_MAX_VAR_SIZE)))
1916 /* Variable of fixed size that goes on the stack. */
1921 /* If we previously made RTL for this decl, it must be an array
1922 whose size was determined by the initializer.
1923 The old address was a register; set that register now
1924 to the proper address. */
1925 if (DECL_RTL_SET_P (decl))
1927 gcc_assert (MEM_P (DECL_RTL (decl)));
1928 gcc_assert (REG_P (XEXP (DECL_RTL (decl), 0)));
1929 oldaddr = XEXP (DECL_RTL (decl), 0);
1932 /* Set alignment we actually gave this decl. */
1933 DECL_ALIGN (decl) = (DECL_MODE (decl) == BLKmode ? BIGGEST_ALIGNMENT
1934 : GET_MODE_BITSIZE (DECL_MODE (decl)));
1935 DECL_USER_ALIGN (decl) = 0;
1937 x = assign_temp (decl, 1, 1, 1);
1938 set_mem_attributes (x, decl, 1);
1939 SET_DECL_RTL (decl, x);
1943 addr = force_operand (XEXP (DECL_RTL (decl), 0), oldaddr);
1944 if (addr != oldaddr)
1945 emit_move_insn (oldaddr, addr);
1949 /* Dynamic-size object: must push space on the stack. */
1951 rtx address, size, x;
1953 /* Record the stack pointer on entry to block, if have
1954 not already done so. */
1955 do_pending_stack_adjust ();
1957 /* Compute the variable's size, in bytes. This will expand any
1958 needed SAVE_EXPRs for the first time. */
1959 size = expand_expr (DECL_SIZE_UNIT (decl), NULL_RTX, VOIDmode, 0);
1962 /* Allocate space on the stack for the variable. Note that
1963 DECL_ALIGN says how the variable is to be aligned and we
1964 cannot use it to conclude anything about the alignment of
1966 address = allocate_dynamic_stack_space (size, NULL_RTX,
1967 TYPE_ALIGN (TREE_TYPE (decl)));
1969 /* Reference the variable indirect through that rtx. */
1970 x = gen_rtx_MEM (DECL_MODE (decl), address);
1971 set_mem_attributes (x, decl, 1);
1972 SET_DECL_RTL (decl, x);
1975 /* Indicate the alignment we actually gave this variable. */
1976 #ifdef STACK_BOUNDARY
1977 DECL_ALIGN (decl) = STACK_BOUNDARY;
1979 DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
1981 DECL_USER_ALIGN (decl) = 0;
1985 /* Emit code to save the current value of stack. */
1987 expand_stack_save (void)
1991 do_pending_stack_adjust ();
1992 emit_stack_save (SAVE_BLOCK, &ret, NULL_RTX);
1996 /* Emit code to restore the current value of stack. */
1998 expand_stack_restore (tree var)
2000 rtx sa = DECL_RTL (var);
2002 emit_stack_restore (SAVE_BLOCK, sa, NULL_RTX);
2005 /* DECL is an anonymous union. CLEANUP is a cleanup for DECL.
2006 DECL_ELTS is the list of elements that belong to DECL's type.
2007 In each, the TREE_VALUE is a VAR_DECL, and the TREE_PURPOSE a cleanup. */
2010 expand_anon_union_decl (tree decl, tree cleanup ATTRIBUTE_UNUSED,
2016 /* If any of the elements are addressable, so is the entire union. */
2017 for (t = decl_elts; t; t = TREE_CHAIN (t))
2018 if (TREE_ADDRESSABLE (TREE_VALUE (t)))
2020 TREE_ADDRESSABLE (decl) = 1;
2025 x = DECL_RTL (decl);
2027 /* Go through the elements, assigning RTL to each. */
2028 for (t = decl_elts; t; t = TREE_CHAIN (t))
2030 tree decl_elt = TREE_VALUE (t);
2031 enum machine_mode mode = TYPE_MODE (TREE_TYPE (decl_elt));
2034 /* If any of the elements are addressable, so is the entire
2036 if (TREE_USED (decl_elt))
2037 TREE_USED (decl) = 1;
2039 /* Propagate the union's alignment to the elements. */
2040 DECL_ALIGN (decl_elt) = DECL_ALIGN (decl);
2041 DECL_USER_ALIGN (decl_elt) = DECL_USER_ALIGN (decl);
2043 /* If the element has BLKmode and the union doesn't, the union is
2044 aligned such that the element doesn't need to have BLKmode, so
2045 change the element's mode to the appropriate one for its size. */
2046 if (mode == BLKmode && DECL_MODE (decl) != BLKmode)
2047 DECL_MODE (decl_elt) = mode
2048 = mode_for_size_tree (DECL_SIZE (decl_elt), MODE_INT, 1);
2050 if (mode == GET_MODE (x))
2053 /* (SUBREG (MEM ...)) at RTL generation time is invalid, so we
2054 instead create a new MEM rtx with the proper mode. */
2055 decl_rtl = adjust_address_nv (x, mode, 0);
2058 gcc_assert (REG_P (x));
2059 decl_rtl = gen_lowpart_SUBREG (mode, x);
2061 SET_DECL_RTL (decl_elt, decl_rtl);
2065 /* Do the insertion of a case label into case_list. The labels are
2066 fed to us in descending order from the sorted vector of case labels used
2067 in the tree part of the middle end. So the list we construct is
2068 sorted in ascending order. The bounds on the case range, LOW and HIGH,
2069 are converted to case's index type TYPE. */
2071 static struct case_node *
2072 add_case_node (struct case_node *head, tree type, tree low, tree high,
2075 tree min_value, max_value;
2076 struct case_node *r;
2078 gcc_assert (TREE_CODE (low) == INTEGER_CST);
2079 gcc_assert (!high || TREE_CODE (high) == INTEGER_CST);
2081 min_value = TYPE_MIN_VALUE (type);
2082 max_value = TYPE_MAX_VALUE (type);
2084 /* If there's no HIGH value, then this is not a case range; it's
2085 just a simple case label. But that's just a degenerate case
2087 If the bounds are equal, turn this into the one-value case. */
2088 if (!high || tree_int_cst_equal (low, high))
2090 /* If the simple case value is unreachable, ignore it. */
2091 if ((TREE_CODE (min_value) == INTEGER_CST
2092 && tree_int_cst_compare (low, min_value) < 0)
2093 || (TREE_CODE (max_value) == INTEGER_CST
2094 && tree_int_cst_compare (low, max_value) > 0))
2096 low = fold_convert (type, low);
2101 /* If the entire case range is unreachable, ignore it. */
2102 if ((TREE_CODE (min_value) == INTEGER_CST
2103 && tree_int_cst_compare (high, min_value) < 0)
2104 || (TREE_CODE (max_value) == INTEGER_CST
2105 && tree_int_cst_compare (low, max_value) > 0))
2108 /* If the lower bound is less than the index type's minimum
2109 value, truncate the range bounds. */
2110 if (TREE_CODE (min_value) == INTEGER_CST
2111 && tree_int_cst_compare (low, min_value) < 0)
2113 low = fold_convert (type, low);
2115 /* If the upper bound is greater than the index type's maximum
2116 value, truncate the range bounds. */
2117 if (TREE_CODE (max_value) == INTEGER_CST
2118 && tree_int_cst_compare (high, max_value) > 0)
2120 high = fold_convert (type, high);
2124 /* Add this label to the chain. Make sure to drop overflow flags. */
2125 r = ggc_alloc (sizeof (struct case_node));
2126 r->low = build_int_cst_wide (TREE_TYPE (low), TREE_INT_CST_LOW (low),
2127 TREE_INT_CST_HIGH (low));
2128 r->high = build_int_cst_wide (TREE_TYPE (high), TREE_INT_CST_LOW (high),
2129 TREE_INT_CST_HIGH (high));
2130 r->code_label = label;
2131 r->parent = r->left = NULL;
2136 /* Maximum number of case bit tests. */
2137 #define MAX_CASE_BIT_TESTS 3
2139 /* By default, enable case bit tests on targets with ashlsi3. */
2140 #ifndef CASE_USE_BIT_TESTS
2141 #define CASE_USE_BIT_TESTS (ashl_optab->handlers[word_mode].insn_code \
2142 != CODE_FOR_nothing)
2146 /* A case_bit_test represents a set of case nodes that may be
2147 selected from using a bit-wise comparison. HI and LO hold
2148 the integer to be tested against, LABEL contains the label
2149 to jump to upon success and BITS counts the number of case
2150 nodes handled by this test, typically the number of bits
2153 struct case_bit_test
2161 /* Determine whether "1 << x" is relatively cheap in word_mode. */
2164 bool lshift_cheap_p (void)
2166 static bool init = false;
2167 static bool cheap = true;
2171 rtx reg = gen_rtx_REG (word_mode, 10000);
2172 int cost = rtx_cost (gen_rtx_ASHIFT (word_mode, const1_rtx, reg), SET);
2173 cheap = cost < COSTS_N_INSNS (3);
2180 /* Comparison function for qsort to order bit tests by decreasing
2181 number of case nodes, i.e. the node with the most cases gets
2185 case_bit_test_cmp (const void *p1, const void *p2)
2187 const struct case_bit_test *d1 = p1;
2188 const struct case_bit_test *d2 = p2;
2190 return d2->bits - d1->bits;
2193 /* Expand a switch statement by a short sequence of bit-wise
2194 comparisons. "switch(x)" is effectively converted into
2195 "if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are
2198 INDEX_EXPR is the value being switched on, which is of
2199 type INDEX_TYPE. MINVAL is the lowest case value of in
2200 the case nodes, of INDEX_TYPE type, and RANGE is highest
2201 value minus MINVAL, also of type INDEX_TYPE. NODES is
2202 the set of case nodes, and DEFAULT_LABEL is the label to
2203 branch to should none of the cases match.
2205 There *MUST* be MAX_CASE_BIT_TESTS or less unique case
2209 emit_case_bit_tests (tree index_type, tree index_expr, tree minval,
2210 tree range, case_node_ptr nodes, rtx default_label)
2212 struct case_bit_test test[MAX_CASE_BIT_TESTS];
2213 enum machine_mode mode;
2214 rtx expr, index, label;
2215 unsigned int i,j,lo,hi;
2216 struct case_node *n;
2220 for (n = nodes; n; n = n->right)
2222 label = label_rtx (n->code_label);
2223 for (i = 0; i < count; i++)
2224 if (label == test[i].label)
2229 gcc_assert (count < MAX_CASE_BIT_TESTS);
2232 test[i].label = label;
2239 lo = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2240 n->low, minval), 1);
2241 hi = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2242 n->high, minval), 1);
2243 for (j = lo; j <= hi; j++)
2244 if (j >= HOST_BITS_PER_WIDE_INT)
2245 test[i].hi |= (HOST_WIDE_INT) 1 << (j - HOST_BITS_PER_INT);
2247 test[i].lo |= (HOST_WIDE_INT) 1 << j;
2250 qsort (test, count, sizeof(*test), case_bit_test_cmp);
2252 index_expr = fold_build2 (MINUS_EXPR, index_type,
2253 fold_convert (index_type, index_expr),
2254 fold_convert (index_type, minval));
2255 index = expand_expr (index_expr, NULL_RTX, VOIDmode, 0);
2256 do_pending_stack_adjust ();
2258 mode = TYPE_MODE (index_type);
2259 expr = expand_expr (range, NULL_RTX, VOIDmode, 0);
2260 emit_cmp_and_jump_insns (index, expr, GTU, NULL_RTX, mode, 1,
2263 index = convert_to_mode (word_mode, index, 0);
2264 index = expand_binop (word_mode, ashl_optab, const1_rtx,
2265 index, NULL_RTX, 1, OPTAB_WIDEN);
2267 for (i = 0; i < count; i++)
2269 expr = immed_double_const (test[i].lo, test[i].hi, word_mode);
2270 expr = expand_binop (word_mode, and_optab, index, expr,
2271 NULL_RTX, 1, OPTAB_WIDEN);
2272 emit_cmp_and_jump_insns (expr, const0_rtx, NE, NULL_RTX,
2273 word_mode, 1, test[i].label);
2276 emit_jump (default_label);
2280 #define HAVE_casesi 0
2283 #ifndef HAVE_tablejump
2284 #define HAVE_tablejump 0
2287 /* Terminate a case (Pascal/Ada) or switch (C) statement
2288 in which ORIG_INDEX is the expression to be tested.
2289 If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
2290 type as given in the source before any compiler conversions.
2291 Generate the code to test it and jump to the right place. */
2294 expand_case (tree exp)
2296 tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE;
2297 rtx default_label = 0;
2298 struct case_node *n;
2299 unsigned int count, uniq;
2305 rtx before_case, end, lab;
2307 tree vec = SWITCH_LABELS (exp);
2308 tree orig_type = TREE_TYPE (exp);
2309 tree index_expr = SWITCH_COND (exp);
2310 tree index_type = TREE_TYPE (index_expr);
2311 int unsignedp = TYPE_UNSIGNED (index_type);
2313 /* The insn after which the case dispatch should finally
2314 be emitted. Zero for a dummy. */
2317 /* A list of case labels; it is first built as a list and it may then
2318 be rearranged into a nearly balanced binary tree. */
2319 struct case_node *case_list = 0;
2321 /* Label to jump to if no case matches. */
2322 tree default_label_decl;
2324 /* The switch body is lowered in gimplify.c, we should never have
2325 switches with a non-NULL SWITCH_BODY here. */
2326 gcc_assert (!SWITCH_BODY (exp));
2327 gcc_assert (SWITCH_LABELS (exp));
2329 do_pending_stack_adjust ();
2331 /* An ERROR_MARK occurs for various reasons including invalid data type. */
2332 if (index_type != error_mark_node)
2335 bitmap label_bitmap;
2337 /* cleanup_tree_cfg removes all SWITCH_EXPR with their index
2338 expressions being INTEGER_CST. */
2339 gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
2341 /* The default case is at the end of TREE_VEC. */
2342 elt = TREE_VEC_ELT (vec, TREE_VEC_LENGTH (vec) - 1);
2343 gcc_assert (!CASE_HIGH (elt));
2344 gcc_assert (!CASE_LOW (elt));
2345 default_label_decl = CASE_LABEL (elt);
2347 for (i = TREE_VEC_LENGTH (vec) - 1; --i >= 0; )
2350 elt = TREE_VEC_ELT (vec, i);
2352 low = CASE_LOW (elt);
2354 high = CASE_HIGH (elt);
2356 /* Discard empty ranges. */
2357 if (high && INT_CST_LT (high, low))
2360 case_list = add_case_node (case_list, index_type, low, high,
2365 /* Make sure start points to something that won't need any
2366 transformation before the end of this function. */
2367 start = get_last_insn ();
2368 if (! NOTE_P (start))
2370 emit_note (NOTE_INSN_DELETED);
2371 start = get_last_insn ();
2374 default_label = label_rtx (default_label_decl);
2376 before_case = get_last_insn ();
2378 /* Get upper and lower bounds of case values. */
2382 label_bitmap = BITMAP_ALLOC (NULL);
2383 for (n = case_list; n; n = n->right)
2385 /* Count the elements and track the largest and smallest
2386 of them (treating them as signed even if they are not). */
2394 if (INT_CST_LT (n->low, minval))
2396 if (INT_CST_LT (maxval, n->high))
2399 /* A range counts double, since it requires two compares. */
2400 if (! tree_int_cst_equal (n->low, n->high))
2403 /* If we have not seen this label yet, then increase the
2404 number of unique case node targets seen. */
2405 lab = label_rtx (n->code_label);
2406 if (!bitmap_bit_p (label_bitmap, CODE_LABEL_NUMBER (lab)))
2408 bitmap_set_bit (label_bitmap, CODE_LABEL_NUMBER (lab));
2413 BITMAP_FREE (label_bitmap);
2415 /* cleanup_tree_cfg removes all SWITCH_EXPR with a single
2416 destination, such as one with a default case only. However,
2417 it doesn't remove cases that are out of range for the switch
2418 type, so we may still get a zero here. */
2421 emit_jump (default_label);
2425 /* Compute span of values. */
2426 range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);
2428 /* Try implementing this switch statement by a short sequence of
2429 bit-wise comparisons. However, we let the binary-tree case
2430 below handle constant index expressions. */
2431 if (CASE_USE_BIT_TESTS
2432 && ! TREE_CONSTANT (index_expr)
2433 && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
2434 && compare_tree_int (range, 0) > 0
2435 && lshift_cheap_p ()
2436 && ((uniq == 1 && count >= 3)
2437 || (uniq == 2 && count >= 5)
2438 || (uniq == 3 && count >= 6)))
2440 /* Optimize the case where all the case values fit in a
2441 word without having to subtract MINVAL. In this case,
2442 we can optimize away the subtraction. */
2443 if (compare_tree_int (minval, 0) > 0
2444 && compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0)
2446 minval = build_int_cst (index_type, 0);
2449 emit_case_bit_tests (index_type, index_expr, minval, range,
2450 case_list, default_label);
2453 /* If range of values is much bigger than number of values,
2454 make a sequence of conditional branches instead of a dispatch.
2455 If the switch-index is a constant, do it this way
2456 because we can optimize it. */
2458 else if (count < case_values_threshold ()
2459 || compare_tree_int (range,
2460 (optimize_size ? 3 : 10) * count) > 0
2461 /* RANGE may be signed, and really large ranges will show up
2462 as negative numbers. */
2463 || compare_tree_int (range, 0) < 0
2464 #ifndef ASM_OUTPUT_ADDR_DIFF_ELT
2467 || !flag_jump_tables
2468 || TREE_CONSTANT (index_expr)
2469 /* If neither casesi or tablejump is available, we can
2470 only go this way. */
2471 || (!HAVE_casesi && !HAVE_tablejump))
2473 index = expand_expr (index_expr, NULL_RTX, VOIDmode, 0);
2475 /* If the index is a short or char that we do not have
2476 an insn to handle comparisons directly, convert it to
2477 a full integer now, rather than letting each comparison
2478 generate the conversion. */
2480 if (GET_MODE_CLASS (GET_MODE (index)) == MODE_INT
2481 && ! have_insn_for (COMPARE, GET_MODE (index)))
2483 enum machine_mode wider_mode;
2484 for (wider_mode = GET_MODE (index); wider_mode != VOIDmode;
2485 wider_mode = GET_MODE_WIDER_MODE (wider_mode))
2486 if (have_insn_for (COMPARE, wider_mode))
2488 index = convert_to_mode (wider_mode, index, unsignedp);
2493 do_pending_stack_adjust ();
2496 index = copy_to_reg (index);
2498 /* We generate a binary decision tree to select the
2499 appropriate target code. This is done as follows:
2501 The list of cases is rearranged into a binary tree,
2502 nearly optimal assuming equal probability for each case.
2504 The tree is transformed into RTL, eliminating
2505 redundant test conditions at the same time.
2507 If program flow could reach the end of the
2508 decision tree an unconditional jump to the
2509 default code is emitted. */
2512 = (TREE_CODE (orig_type) != ENUMERAL_TYPE
2513 && estimate_case_costs (case_list));
2514 balance_case_nodes (&case_list, NULL);
2515 emit_case_nodes (index, case_list, default_label, index_type);
2516 emit_jump (default_label);
2520 table_label = gen_label_rtx ();
2521 if (! try_casesi (index_type, index_expr, minval, range,
2522 table_label, default_label))
2526 /* Index jumptables from zero for suitable values of
2527 minval to avoid a subtraction. */
2529 && compare_tree_int (minval, 0) > 0
2530 && compare_tree_int (minval, 3) < 0)
2532 minval = build_int_cst (index_type, 0);
2536 ok = try_tablejump (index_type, index_expr, minval, range,
2537 table_label, default_label);
2541 /* Get table of labels to jump to, in order of case index. */
2543 ncases = tree_low_cst (range, 0) + 1;
2544 labelvec = alloca (ncases * sizeof (rtx));
2545 memset (labelvec, 0, ncases * sizeof (rtx));
2547 for (n = case_list; n; n = n->right)
2549 /* Compute the low and high bounds relative to the minimum
2550 value since that should fit in a HOST_WIDE_INT while the
2551 actual values may not. */
2553 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2554 n->low, minval), 1);
2555 HOST_WIDE_INT i_high
2556 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2557 n->high, minval), 1);
2560 for (i = i_low; i <= i_high; i ++)
2562 = gen_rtx_LABEL_REF (Pmode, label_rtx (n->code_label));
2565 /* Fill in the gaps with the default. */
2566 for (i = 0; i < ncases; i++)
2567 if (labelvec[i] == 0)
2568 labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label);
2570 /* Output the table. */
2571 emit_label (table_label);
2573 if (CASE_VECTOR_PC_RELATIVE || flag_pic)
2574 emit_jump_insn (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
2575 gen_rtx_LABEL_REF (Pmode, table_label),
2576 gen_rtvec_v (ncases, labelvec),
2577 const0_rtx, const0_rtx));
2579 emit_jump_insn (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
2580 gen_rtvec_v (ncases, labelvec)));
2582 /* Record no drop-through after the table. */
2586 before_case = NEXT_INSN (before_case);
2587 end = get_last_insn ();
2588 fail = squeeze_notes (&before_case, &end);
2590 reorder_insns (before_case, end, start);
2596 /* Generate code to jump to LABEL if OP1 and OP2 are equal. */
2599 do_jump_if_equal (rtx op1, rtx op2, rtx label, int unsignedp)
2601 if (GET_CODE (op1) == CONST_INT && GET_CODE (op2) == CONST_INT)
2607 emit_cmp_and_jump_insns (op1, op2, EQ, NULL_RTX,
2608 (GET_MODE (op1) == VOIDmode
2609 ? GET_MODE (op2) : GET_MODE (op1)),
2613 /* Not all case values are encountered equally. This function
2614 uses a heuristic to weight case labels, in cases where that
2615 looks like a reasonable thing to do.
2617 Right now, all we try to guess is text, and we establish the
2620 chars above space: 16
2629 If we find any cases in the switch that are not either -1 or in the range
2630 of valid ASCII characters, or are control characters other than those
2631 commonly used with "\", don't treat this switch scanning text.
2633 Return 1 if these nodes are suitable for cost estimation, otherwise
2637 estimate_case_costs (case_node_ptr node)
2639 tree min_ascii = integer_minus_one_node;
2640 tree max_ascii = build_int_cst (TREE_TYPE (node->high), 127);
2644 /* If we haven't already made the cost table, make it now. Note that the
2645 lower bound of the table is -1, not zero. */
2647 if (! cost_table_initialized)
2649 cost_table_initialized = 1;
2651 for (i = 0; i < 128; i++)
2654 COST_TABLE (i) = 16;
2655 else if (ISPUNCT (i))
2657 else if (ISCNTRL (i))
2658 COST_TABLE (i) = -1;
2661 COST_TABLE (' ') = 8;
2662 COST_TABLE ('\t') = 4;
2663 COST_TABLE ('\0') = 4;
2664 COST_TABLE ('\n') = 2;
2665 COST_TABLE ('\f') = 1;
2666 COST_TABLE ('\v') = 1;
2667 COST_TABLE ('\b') = 1;
2670 /* See if all the case expressions look like text. It is text if the
2671 constant is >= -1 and the highest constant is <= 127. Do all comparisons
2672 as signed arithmetic since we don't want to ever access cost_table with a
2673 value less than -1. Also check that none of the constants in a range
2674 are strange control characters. */
2676 for (n = node; n; n = n->right)
2678 if ((INT_CST_LT (n->low, min_ascii)) || INT_CST_LT (max_ascii, n->high))
2681 for (i = (HOST_WIDE_INT) TREE_INT_CST_LOW (n->low);
2682 i <= (HOST_WIDE_INT) TREE_INT_CST_LOW (n->high); i++)
2683 if (COST_TABLE (i) < 0)
2687 /* All interesting values are within the range of interesting
2688 ASCII characters. */
2692 /* Take an ordered list of case nodes
2693 and transform them into a near optimal binary tree,
2694 on the assumption that any target code selection value is as
2695 likely as any other.
2697 The transformation is performed by splitting the ordered
2698 list into two equal sections plus a pivot. The parts are
2699 then attached to the pivot as left and right branches. Each
2700 branch is then transformed recursively. */
2703 balance_case_nodes (case_node_ptr *head, case_node_ptr parent)
2716 /* Count the number of entries on branch. Also count the ranges. */
2720 if (!tree_int_cst_equal (np->low, np->high))
2724 cost += COST_TABLE (TREE_INT_CST_LOW (np->high));
2728 cost += COST_TABLE (TREE_INT_CST_LOW (np->low));
2736 /* Split this list if it is long enough for that to help. */
2741 /* Find the place in the list that bisects the list's total cost,
2742 Here I gets half the total cost. */
2747 /* Skip nodes while their cost does not reach that amount. */
2748 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
2749 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->high));
2750 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->low));
2753 npp = &(*npp)->right;
2758 /* Leave this branch lopsided, but optimize left-hand
2759 side and fill in `parent' fields for right-hand side. */
2761 np->parent = parent;
2762 balance_case_nodes (&np->left, np);
2763 for (; np->right; np = np->right)
2764 np->right->parent = np;
2768 /* If there are just three nodes, split at the middle one. */
2770 npp = &(*npp)->right;
2773 /* Find the place in the list that bisects the list's total cost,
2774 where ranges count as 2.
2775 Here I gets half the total cost. */
2776 i = (i + ranges + 1) / 2;
2779 /* Skip nodes while their cost does not reach that amount. */
2780 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
2785 npp = &(*npp)->right;
2790 np->parent = parent;
2793 /* Optimize each of the two split parts. */
2794 balance_case_nodes (&np->left, np);
2795 balance_case_nodes (&np->right, np);
2799 /* Else leave this branch as one level,
2800 but fill in `parent' fields. */
2802 np->parent = parent;
2803 for (; np->right; np = np->right)
2804 np->right->parent = np;
2809 /* Search the parent sections of the case node tree
2810 to see if a test for the lower bound of NODE would be redundant.
2811 INDEX_TYPE is the type of the index expression.
2813 The instructions to generate the case decision tree are
2814 output in the same order as nodes are processed so it is
2815 known that if a parent node checks the range of the current
2816 node minus one that the current node is bounded at its lower
2817 span. Thus the test would be redundant. */
2820 node_has_low_bound (case_node_ptr node, tree index_type)
2823 case_node_ptr pnode;
2825 /* If the lower bound of this node is the lowest value in the index type,
2826 we need not test it. */
2828 if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type)))
2831 /* If this node has a left branch, the value at the left must be less
2832 than that at this node, so it cannot be bounded at the bottom and
2833 we need not bother testing any further. */
2838 low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low),
2840 build_int_cst (TREE_TYPE (node->low), 1));
2842 /* If the subtraction above overflowed, we can't verify anything.
2843 Otherwise, look for a parent that tests our value - 1. */
2845 if (! tree_int_cst_lt (low_minus_one, node->low))
2848 for (pnode = node->parent; pnode; pnode = pnode->parent)
2849 if (tree_int_cst_equal (low_minus_one, pnode->high))
2855 /* Search the parent sections of the case node tree
2856 to see if a test for the upper bound of NODE would be redundant.
2857 INDEX_TYPE is the type of the index expression.
2859 The instructions to generate the case decision tree are
2860 output in the same order as nodes are processed so it is
2861 known that if a parent node checks the range of the current
2862 node plus one that the current node is bounded at its upper
2863 span. Thus the test would be redundant. */
2866 node_has_high_bound (case_node_ptr node, tree index_type)
2869 case_node_ptr pnode;
2871 /* If there is no upper bound, obviously no test is needed. */
2873 if (TYPE_MAX_VALUE (index_type) == NULL)
2876 /* If the upper bound of this node is the highest value in the type
2877 of the index expression, we need not test against it. */
2879 if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type)))
2882 /* If this node has a right branch, the value at the right must be greater
2883 than that at this node, so it cannot be bounded at the top and
2884 we need not bother testing any further. */
2889 high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high),
2891 build_int_cst (TREE_TYPE (node->high), 1));
2893 /* If the addition above overflowed, we can't verify anything.
2894 Otherwise, look for a parent that tests our value + 1. */
2896 if (! tree_int_cst_lt (node->high, high_plus_one))
2899 for (pnode = node->parent; pnode; pnode = pnode->parent)
2900 if (tree_int_cst_equal (high_plus_one, pnode->low))
2906 /* Search the parent sections of the
2907 case node tree to see if both tests for the upper and lower
2908 bounds of NODE would be redundant. */
2911 node_is_bounded (case_node_ptr node, tree index_type)
2913 return (node_has_low_bound (node, index_type)
2914 && node_has_high_bound (node, index_type));
2917 /* Emit step-by-step code to select a case for the value of INDEX.
2918 The thus generated decision tree follows the form of the
2919 case-node binary tree NODE, whose nodes represent test conditions.
2920 INDEX_TYPE is the type of the index of the switch.
2922 Care is taken to prune redundant tests from the decision tree
2923 by detecting any boundary conditions already checked by
2924 emitted rtx. (See node_has_high_bound, node_has_low_bound
2925 and node_is_bounded, above.)
2927 Where the test conditions can be shown to be redundant we emit
2928 an unconditional jump to the target code. As a further
2929 optimization, the subordinates of a tree node are examined to
2930 check for bounded nodes. In this case conditional and/or
2931 unconditional jumps as a result of the boundary check for the
2932 current node are arranged to target the subordinates associated
2933 code for out of bound conditions on the current node.
2935 We can assume that when control reaches the code generated here,
2936 the index value has already been compared with the parents
2937 of this node, and determined to be on the same side of each parent
2938 as this node is. Thus, if this node tests for the value 51,
2939 and a parent tested for 52, we don't need to consider
2940 the possibility of a value greater than 51. If another parent
2941 tests for the value 50, then this node need not test anything. */
2944 emit_case_nodes (rtx index, case_node_ptr node, rtx default_label,
2947 /* If INDEX has an unsigned type, we must make unsigned branches. */
2948 int unsignedp = TYPE_UNSIGNED (index_type);
2949 enum machine_mode mode = GET_MODE (index);
2950 enum machine_mode imode = TYPE_MODE (index_type);
2952 /* Handle indices detected as constant during RTL expansion. */
2953 if (mode == VOIDmode)
2956 /* See if our parents have already tested everything for us.
2957 If they have, emit an unconditional jump for this node. */
2958 if (node_is_bounded (node, index_type))
2959 emit_jump (label_rtx (node->code_label));
2961 else if (tree_int_cst_equal (node->low, node->high))
2963 /* Node is single valued. First see if the index expression matches
2964 this node and then check our children, if any. */
2966 do_jump_if_equal (index,
2967 convert_modes (mode, imode,
2968 expand_expr (node->low, NULL_RTX,
2971 label_rtx (node->code_label), unsignedp);
2973 if (node->right != 0 && node->left != 0)
2975 /* This node has children on both sides.
2976 Dispatch to one side or the other
2977 by comparing the index value with this node's value.
2978 If one subtree is bounded, check that one first,
2979 so we can avoid real branches in the tree. */
2981 if (node_is_bounded (node->right, index_type))
2983 emit_cmp_and_jump_insns (index,
2986 expand_expr (node->high, NULL_RTX,
2989 GT, NULL_RTX, mode, unsignedp,
2990 label_rtx (node->right->code_label));
2991 emit_case_nodes (index, node->left, default_label, index_type);
2994 else if (node_is_bounded (node->left, index_type))
2996 emit_cmp_and_jump_insns (index,
2999 expand_expr (node->high, NULL_RTX,
3002 LT, NULL_RTX, mode, unsignedp,
3003 label_rtx (node->left->code_label));
3004 emit_case_nodes (index, node->right, default_label, index_type);
3007 /* If both children are single-valued cases with no
3008 children, finish up all the work. This way, we can save
3009 one ordered comparison. */
3010 else if (tree_int_cst_equal (node->right->low, node->right->high)
3011 && node->right->left == 0
3012 && node->right->right == 0
3013 && tree_int_cst_equal (node->left->low, node->left->high)
3014 && node->left->left == 0
3015 && node->left->right == 0)
3017 /* Neither node is bounded. First distinguish the two sides;
3018 then emit the code for one side at a time. */
3020 /* See if the value matches what the right hand side
3022 do_jump_if_equal (index,
3023 convert_modes (mode, imode,
3024 expand_expr (node->right->low,
3028 label_rtx (node->right->code_label),
3031 /* See if the value matches what the left hand side
3033 do_jump_if_equal (index,
3034 convert_modes (mode, imode,
3035 expand_expr (node->left->low,
3039 label_rtx (node->left->code_label),
3045 /* Neither node is bounded. First distinguish the two sides;
3046 then emit the code for one side at a time. */
3048 tree test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
3050 /* See if the value is on the right. */
3051 emit_cmp_and_jump_insns (index,
3054 expand_expr (node->high, NULL_RTX,
3057 GT, NULL_RTX, mode, unsignedp,
3058 label_rtx (test_label));
3060 /* Value must be on the left.
3061 Handle the left-hand subtree. */
3062 emit_case_nodes (index, node->left, default_label, index_type);
3063 /* If left-hand subtree does nothing,
3065 emit_jump (default_label);
3067 /* Code branches here for the right-hand subtree. */
3068 expand_label (test_label);
3069 emit_case_nodes (index, node->right, default_label, index_type);
3073 else if (node->right != 0 && node->left == 0)
3075 /* Here we have a right child but no left so we issue a conditional
3076 branch to default and process the right child.
3078 Omit the conditional branch to default if the right child
3079 does not have any children and is single valued; it would
3080 cost too much space to save so little time. */
3082 if (node->right->right || node->right->left
3083 || !tree_int_cst_equal (node->right->low, node->right->high))
3085 if (!node_has_low_bound (node, index_type))
3087 emit_cmp_and_jump_insns (index,
3090 expand_expr (node->high, NULL_RTX,
3093 LT, NULL_RTX, mode, unsignedp,
3097 emit_case_nodes (index, node->right, default_label, index_type);
3100 /* We cannot process node->right normally
3101 since we haven't ruled out the numbers less than
3102 this node's value. So handle node->right explicitly. */
3103 do_jump_if_equal (index,
3106 expand_expr (node->right->low, NULL_RTX,
3109 label_rtx (node->right->code_label), unsignedp);
3112 else if (node->right == 0 && node->left != 0)
3114 /* Just one subtree, on the left. */
3115 if (node->left->left || node->left->right
3116 || !tree_int_cst_equal (node->left->low, node->left->high))
3118 if (!node_has_high_bound (node, index_type))
3120 emit_cmp_and_jump_insns (index,
3123 expand_expr (node->high, NULL_RTX,
3126 GT, NULL_RTX, mode, unsignedp,
3130 emit_case_nodes (index, node->left, default_label, index_type);
3133 /* We cannot process node->left normally
3134 since we haven't ruled out the numbers less than
3135 this node's value. So handle node->left explicitly. */
3136 do_jump_if_equal (index,
3139 expand_expr (node->left->low, NULL_RTX,
3142 label_rtx (node->left->code_label), unsignedp);
3147 /* Node is a range. These cases are very similar to those for a single
3148 value, except that we do not start by testing whether this node
3149 is the one to branch to. */
3151 if (node->right != 0 && node->left != 0)
3153 /* Node has subtrees on both sides.
3154 If the right-hand subtree is bounded,
3155 test for it first, since we can go straight there.
3156 Otherwise, we need to make a branch in the control structure,
3157 then handle the two subtrees. */
3158 tree test_label = 0;
3160 if (node_is_bounded (node->right, index_type))
3161 /* Right hand node is fully bounded so we can eliminate any
3162 testing and branch directly to the target code. */
3163 emit_cmp_and_jump_insns (index,
3166 expand_expr (node->high, NULL_RTX,
3169 GT, NULL_RTX, mode, unsignedp,
3170 label_rtx (node->right->code_label));
3173 /* Right hand node requires testing.
3174 Branch to a label where we will handle it later. */
3176 test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
3177 emit_cmp_and_jump_insns (index,
3180 expand_expr (node->high, NULL_RTX,
3183 GT, NULL_RTX, mode, unsignedp,
3184 label_rtx (test_label));
3187 /* Value belongs to this node or to the left-hand subtree. */
3189 emit_cmp_and_jump_insns (index,
3192 expand_expr (node->low, NULL_RTX,
3195 GE, NULL_RTX, mode, unsignedp,
3196 label_rtx (node->code_label));
3198 /* Handle the left-hand subtree. */
3199 emit_case_nodes (index, node->left, default_label, index_type);
3201 /* If right node had to be handled later, do that now. */
3205 /* If the left-hand subtree fell through,
3206 don't let it fall into the right-hand subtree. */
3207 emit_jump (default_label);
3209 expand_label (test_label);
3210 emit_case_nodes (index, node->right, default_label, index_type);
3214 else if (node->right != 0 && node->left == 0)
3216 /* Deal with values to the left of this node,
3217 if they are possible. */
3218 if (!node_has_low_bound (node, index_type))
3220 emit_cmp_and_jump_insns (index,
3223 expand_expr (node->low, NULL_RTX,
3226 LT, NULL_RTX, mode, unsignedp,
3230 /* Value belongs to this node or to the right-hand subtree. */
3232 emit_cmp_and_jump_insns (index,
3235 expand_expr (node->high, NULL_RTX,
3238 LE, NULL_RTX, mode, unsignedp,
3239 label_rtx (node->code_label));
3241 emit_case_nodes (index, node->right, default_label, index_type);
3244 else if (node->right == 0 && node->left != 0)
3246 /* Deal with values to the right of this node,
3247 if they are possible. */
3248 if (!node_has_high_bound (node, index_type))
3250 emit_cmp_and_jump_insns (index,
3253 expand_expr (node->high, NULL_RTX,
3256 GT, NULL_RTX, mode, unsignedp,
3260 /* Value belongs to this node or to the left-hand subtree. */
3262 emit_cmp_and_jump_insns (index,
3265 expand_expr (node->low, NULL_RTX,
3268 GE, NULL_RTX, mode, unsignedp,
3269 label_rtx (node->code_label));
3271 emit_case_nodes (index, node->left, default_label, index_type);
3276 /* Node has no children so we check low and high bounds to remove
3277 redundant tests. Only one of the bounds can exist,
3278 since otherwise this node is bounded--a case tested already. */
3279 int high_bound = node_has_high_bound (node, index_type);
3280 int low_bound = node_has_low_bound (node, index_type);
3282 if (!high_bound && low_bound)
3284 emit_cmp_and_jump_insns (index,
3287 expand_expr (node->high, NULL_RTX,
3290 GT, NULL_RTX, mode, unsignedp,
3294 else if (!low_bound && high_bound)
3296 emit_cmp_and_jump_insns (index,
3299 expand_expr (node->low, NULL_RTX,
3302 LT, NULL_RTX, mode, unsignedp,
3305 else if (!low_bound && !high_bound)
3307 /* Widen LOW and HIGH to the same width as INDEX. */
3308 tree type = lang_hooks.types.type_for_mode (mode, unsignedp);
3309 tree low = build1 (CONVERT_EXPR, type, node->low);
3310 tree high = build1 (CONVERT_EXPR, type, node->high);
3311 rtx low_rtx, new_index, new_bound;
3313 /* Instead of doing two branches, emit one unsigned branch for
3314 (index-low) > (high-low). */
3315 low_rtx = expand_expr (low, NULL_RTX, mode, 0);
3316 new_index = expand_simple_binop (mode, MINUS, index, low_rtx,
3317 NULL_RTX, unsignedp,
3319 new_bound = expand_expr (fold_build2 (MINUS_EXPR, type,
3323 emit_cmp_and_jump_insns (new_index, new_bound, GT, NULL_RTX,
3324 mode, 1, default_label);
3327 emit_jump (label_rtx (node->code_label));