mirror/gcc
2
0
Fork 0
mirror of git://gcc.gnu.org/git/gcc.git synced 2025-03-22 03:30:29 +08:00
Code Issues Packages Projects Releases Wiki Activity

ix86: Add peephole2 for *add<mode>3_cc_overflow_1 followed by matching memory store [PR94857]

Browse Source 
The following peephole2 changes:
-	addl	(%rdi), %esi
+	xorl	%eax, %eax
+	addl	%esi, (%rdi)
 	setc	%al
-	movl	%esi, (%rdi)
-	movzbl	%al, %eax
 	ret
on the testcase.  *add<mode>3_cc_overflow_1, being an add{l,q} insn, is
commutative, so if TARGET_READ_MODIFY_WRITE we can replace
addl (%rdi), %esi; movl %esi, (%rdi)
with
addl %esi, (%rdi)
if %esi is dead after those two insns.

2020-05-08  Jakub Jelinek  <jakub@redhat.com>

	PR target/94857
	* config/i386/i386.md (peephole2 after *add<mode>3_cc_overflow_1): New
	define_peephole2.

	* gcc.target/i386/pr94857.c: New test.
This commit is contained in:
Jakub Jelinek 2020-05-08 10:03:56 +02:00
parent a139bc2b49
commit a229f9b373
4 changed files with 37 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
gcc/ChangeLog
View File

@ -1,5 +1,9 @@
2020-05-08 Jakub Jelinek <jakub@redhat.com>
PR target/94857
* config/i386/i386.md (peephole2 after *add<mode>3_cc_overflow_1): New
define_peephole2.
PR middle-end/94724
* tree.c (get_narrower): Reuse the op temporary instead of
shadowing it.

17
gcc/config/i386/i386.md
View File

@ -6992,6 +6992,23 @@
[(set_attr "type" "alu")
(set_attr "mode" "<MODE>")])
(define_peephole2
[(parallel [(set (reg:CCC FLAGS_REG)
(compare:CCC
(plus:SWI (match_operand:SWI 0 "general_reg_operand")
(match_operand:SWI 1 "memory_operand"))
(match_dup 0)))
(set (match_dup 0) (plus:SWI (match_dup 0) (match_dup 1)))])
(set (match_dup 1) (match_dup 0))]
"(TARGET_READ_MODIFY_WRITE || optimize_insn_for_size_p ())
&& peep2_reg_dead_p (2, operands[0])
&& !reg_overlap_mentioned_p (operands[0], operands[1])"
[(parallel [(set (reg:CCC FLAGS_REG)
(compare:CCC
(plus:SWI (match_dup 1) (match_dup 0))
(match_dup 1)))
(set (match_dup 1) (plus:SWI (match_dup 1) (match_dup 0)))])])
(define_insn "*addsi3_zext_cc_overflow_1"
[(set (reg:CCC FLAGS_REG)
(compare:CCC

3
gcc/testsuite/ChangeLog
View File

@ -1,5 +1,8 @@
2020-05-08 Jakub Jelinek <jakub@redhat.com>
PR target/94857
* gcc.target/i386/pr94857.c: New test.
PR tree-optimization/94783
* gcc.dg/tree-ssa/pr94783.c: New test.

13
gcc/testsuite/gcc.target/i386/pr94857.c Normal file
View File

@ -0,0 +1,13 @@
/* PR target/94857 */
/* { dg-do compile } */
/* { dg-options "-O2 -mtune=skylake -masm=att" } */
/* { dg-additional-options "-mregparm=2" { target ia32 } } */
/* { dg-final { scan-assembler "\taddl\t%\[a-z0-9]\*, \\\(" } } */
int
foo (unsigned *p, unsigned x)
{
unsigned u = *p;
*p += x;
return u > *p;
}