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From afd539adfe762adb57863299a11987b7e20e7987 Mon Sep 17 00:00:00 2001
From: liuhongt <hongtao.liu@intel.com>
Date: Wed, 5 Jul 2023 13:45:11 +0800
Subject: [PATCH 12/28] Disparage slightly for the alternative which move
DFmode between SSE_REGS and GENERAL_REGS.
For testcase
void __cond_swap(double* __x, double* __y) {
bool __r = (*__x < *__y);
auto __tmp = __r ? *__x : *__y;
*__y = __r ? *__y : *__x;
*__x = __tmp;
}
GCC-14 with -O2 and -march=x86-64 options generates the following code:
__cond_swap(double*, double*):
movsd xmm1, QWORD PTR [rdi]
movsd xmm0, QWORD PTR [rsi]
comisd xmm0, xmm1
jbe .L2
movq rax, xmm1
movapd xmm1, xmm0
movq xmm0, rax
.L2:
movsd QWORD PTR [rsi], xmm1
movsd QWORD PTR [rdi], xmm0
ret
rax is used to save and restore DFmode value. In RA both GENERAL_REGS
and SSE_REGS cost zero since we didn't disparage the
alternative in movdf_internal pattern, according to register
allocation order, GENERAL_REGS is allocated. The patch add ? for
alternative (r,v) and (v,r) just like we did for movsf/hf/bf_internal
pattern, after that we get optimal RA.
__cond_swap:
.LFB0:
.cfi_startproc
movsd (%rdi), %xmm1
movsd (%rsi), %xmm0
comisd %xmm1, %xmm0
jbe .L2
movapd %xmm1, %xmm2
movapd %xmm0, %xmm1
movapd %xmm2, %xmm0
.L2:
movsd %xmm1, (%rsi)
movsd %xmm0, (%rdi)
ret
gcc/ChangeLog:
PR target/110170
* config/i386/i386.md (movdf_internal): Disparage slightly for
2 alternatives (r,v) and (v,r) by adding constraint modifier
'?'.
gcc/testsuite/ChangeLog:
* gcc.target/i386/pr110170-3.c: New test.
(cherry picked from commit 37a231cc7594d12ba0822077018aad751a6fb94e)
---
gcc/config/i386/i386.md | 4 ++--
gcc/testsuite/gcc.target/i386/pr110170-3.c | 11 +++++++++++
2 files changed, 13 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr110170-3.c
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index be07be10d..71691f598 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -3582,9 +3582,9 @@
;; Possible store forwarding (partial memory) stall in alternatives 4, 6 and 7.
(define_insn "*movdf_internal"
[(set (match_operand:DF 0 "nonimmediate_operand"
- "=Yf*f,m ,Yf*f,?r ,!o,?*r ,!o,!o,?r,?m,?r,?r,v,v,v,m,*x,*x,*x,m ,r ,v,r ,o ,r ,m")
+ "=Yf*f,m ,Yf*f,?r ,!o,?*r ,!o,!o,?r,?m,?r,?r,v,v,v,m,*x,*x,*x,m ,?r,?v,r ,o ,r ,m")
(match_operand:DF 1 "general_operand"
- "Yf*fm,Yf*f,G ,roF,r ,*roF,*r,F ,rm,rC,C ,F ,C,v,m,v,C ,*x,m ,*x,v,r ,roF,rF,rmF,rC"))]
+ "Yf*fm,Yf*f,G ,roF,r ,*roF,*r,F ,rm,rC,C ,F ,C,v,m,v,C ,*x,m ,*x, v, r,roF,rF,rmF,rC"))]
"!(MEM_P (operands[0]) && MEM_P (operands[1]))
&& (lra_in_progress || reload_completed
|| !CONST_DOUBLE_P (operands[1])
diff --git a/gcc/testsuite/gcc.target/i386/pr110170-3.c b/gcc/testsuite/gcc.target/i386/pr110170-3.c
new file mode 100644
index 000000000..70daa89e9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr110170-3.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O2 -fno-if-conversion -fno-if-conversion2" } */
+/* { dg-final { scan-assembler-not {(?n)movq.*r} } } */
+
+void __cond_swap(double* __x, double* __y) {
+ _Bool __r = (*__x < *__y);
+ double __tmp = __r ? *__x : *__y;
+ *__y = __r ? *__y : *__x;
+ *__x = __tmp;
+}
+
--
2.31.1
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