https://gcc.gnu.org/g:8f5fac56ca39e99d7a9ad6a0c067c75e6ffcd2cf
commit r16-1656-g8f5fac56ca39e99d7a9ad6a0c067c75e6ffcd2cf
Author: Uros Bizjak <ubiz...@gmail.com>
Date: Tue Jun 24 11:02:02 2025 +0200
i386: Convert LEA stack adjust insn to SUB when FLAGS_REG is dead
ADD/SUB is faster than LEA for most processors. Also, there are
several peephole2 patterns available that convert prologue esp
subtractions to pushes (at the end of i386.md). These process only
patterns with flags reg clobber, so they are ineffective
with clobber-less stack ptr adjustments, introduced by r16-1551
("x86: Enable separate shrink wrapping").
Introduce a peephole2 pattern that adds a clobber to a clobber-less
stack ptr adjustments when FLAGS_REG is dead.
gcc/ChangeLog:
* config/i386/i386.md
(@pro_epilogue_adjust_stack_add_nocc<mode>): Add type attribute.
(pro_epilogue_adjust_stack_add_nocc peephole2 pattern):
Convert pro_epilogue_adjust_stack_add_nocc variant to
pro_epilogue_adjust_stack_add when FLAGS_REG is dead.
Diff:
---
gcc/config/i386/i386.md | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 423ef48e518f..41a86544bbf7 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -27449,7 +27449,7 @@
(cond [(and (eq_attr "alternative" "0")
(not (match_test "TARGET_OPT_AGU")))
(const_string "alu")
- (match_operand:<MODE> 2 "const0_operand")
+ (match_operand 2 "const0_operand")
(const_string "imov")
]
(const_string "lea")))
@@ -27470,7 +27470,7 @@
(clobber (mem:BLK (scratch)))]
""
{
- if (operands[2] == CONST0_RTX (<MODE>mode))
+ if (get_attr_type (insn) == TYPE_IMOV)
return "mov{<imodesuffix>}\t{%1, %0|%0, %1}";
else
{
@@ -27478,13 +27478,31 @@
return "lea{<imodesuffix>}\t{%E2, %0|%0, %E2}";
}
}
- [(set (attr "length_immediate")
+ [(set (attr "type")
+ (cond [(match_operand 2 "const0_operand")
+ (const_string "imov")
+ ]
+ (const_string "lea")))
+ (set (attr "length_immediate")
(cond [(eq_attr "type" "imov")
(const_string "0")
]
(const_string "*")))
(set_attr "mode" "<MODE>")])
+(define_peephole2
+ [(parallel
+ [(set (match_operand:P 0 "register_operand")
+ (plus:P (match_dup 0)
+ (match_operand:P 1 "<nonmemory_operand>")))
+ (clobber (mem:BLK (scratch)))])]
+ "peep2_regno_dead_p (0, FLAGS_REG)"
+ [(parallel
+ [(set (match_dup 0)
+ (plus:P (match_dup 0) (match_dup 1)))
+ (clobber (reg:CC FLAGS_REG))
+ (clobber (mem:BLK (scratch)))])])
+
(define_insn "@pro_epilogue_adjust_stack_sub_<mode>"
[(set (match_operand:P 0 "register_operand" "=r")
(minus:P (match_operand:P 1 "register_operand" "0")
