[PATCH] [i386] Fix a small performance regression. [PR98348]

[PATCH] [i386] Fix a small performance regression. [PR98348]

[Hongtao Liu]

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Hi:
  This patch is about to add a pre-reload splitter to transform
vpcmpeqd with a zero operand to vptestnmd, which could save a vpxor
instruction.

.i.e
-       vpxor   %xmm1, %xmm1, %xmm1
-       vpcmpd  $0, %zmm1, %zmm0, %k0
+       vptestnmd       %zmm0, %zmm0, %k0
        vpmovm2d zmm0, k0

Bootstrapped and regtested on x86-64_iinux-gnu{-m32,}.

gcc/ChangeLog:

        PR target/98348
        * config/i386/sse.md (*<avx512>_eq<mode>3): New pre_reload
        splitter.
        (*<avx512>_eq<mode>3): Changed from combine splitter to
        pre-reload splitter.

gcc/testsuite/ChangeLog:

        PR target/98348
        * gcc.target/i386/pr98348.c: New test.


-- 
BR,
Hongtao

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From 7e59a44e079f6f4c9d39d625aaa3c5023cb545aa Mon Sep 17 00:00:00 2001
From: liuhongt <hongtao.liu@intel.com>
Date: Fri, 16 Apr 2021 15:32:14 +0800
Subject: [PATCH] [i386] Add pre-reload splitter for blow transformation.

-       vpxor   %xmm1, %xmm1, %xmm1
-       vpcmpd  $0, %zmm1, %zmm0, %k0
+       vptestnmd       %zmm0, %zmm0, %k0
	vpmovm2d zmm0, k0

gcc/ChangeLog:

	PR target/98348
	* config/i386/sse.md (*<avx512>_eq<mode>3): New pre_reload
	splitter.
	(*<avx512>_eq<mode>3): Changed from combine splitter to
	pre-reload splitter.

gcc/testsuite/ChangeLog:

	PR target/98348
	* gcc.target/i386/pr98348.c: New test.
---
 gcc/config/i386/sse.md                  | 23 +++++++++-
 gcc/testsuite/gcc.target/i386/pr98348.c | 57 +++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr98348.c

diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 9d3728d1cb0..f2c16db1c1a 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -3273,7 +3273,7 @@ (define_int_attr pcmp_signed_mask
 ;; For signed comparison, handle EQ 0: NEQ 4,
 ;; for unsigned comparison extra handle LE:2, NLE:6, equivalent to EQ and NEQ.
 
-(define_split
+(define_insn_and_split "*<avx512>_ucmp<mode>3"
   [(set (match_operand:<avx512fmaskmode> 0 "register_operand")
 	(unspec:<avx512fmaskmode>
 	  [(us_minus:VI12_AVX512VL
@@ -3282,9 +3282,11 @@ (define_split
 	   (match_operand:VI12_AVX512VL 3 "const0_operand")
 	   (match_operand:SI 4 "const_0_to_7_operand")]
 	  UNSPEC_PCMP_ITER))]
-  "TARGET_AVX512BW
+  "TARGET_AVX512BW && ix86_pre_reload_split ()
   && ix86_binary_operator_ok (US_MINUS, <MODE>mode, operands)
   && (INTVAL (operands[4]) & <pcmp_signed_mask>) == 0"
+  "#"
+  "&& 1"
   [(const_int 0)]
   {
     /* LE: 2, NLT: 5, NLE: 6, LT: 1  */
@@ -13026,6 +13028,23 @@ (define_insn "<avx512>_eq<mode>3<mask_scalar_merge_name>_1"
    (set_attr "prefix" "evex")
    (set_attr "mode" "<sseinsnmode>")])
 
+(define_insn_and_split "*<avx512>_eq<mode>3"
+  [(set (match_operand:<avx512fmaskmode> 0 "register_operand")
+	(unspec:<avx512fmaskmode>
+	  [(match_operand:VI_AVX512BW 1 "nonimm_or_0_operand")
+	   (match_operand:VI_AVX512BW 2 "nonimm_or_0_operand")
+	   (const_int 0)]
+	  UNSPEC_PCMP_ITER))]
+  "TARGET_AVX512F && ix86_pre_reload_split ()
+  && (operands[1] == CONST0_RTX (<MODE>mode)
+      || operands[2] == CONST0_RTX (<MODE>mode))"
+  "#"
+  "&& 1"
+  [(set (match_dup 0)
+  	(unspec:<avx512fmaskmode>
+	  [(match_dup 1) (match_dup 2)]
+	  UNSPEC_MASKED_EQ))])
+
 (define_insn "*sse4_1_eqv2di3"
   [(set (match_operand:V2DI 0 "register_operand" "=Yr,*x,x")
 	(eq:V2DI
diff --git a/gcc/testsuite/gcc.target/i386/pr98348.c b/gcc/testsuite/gcc.target/i386/pr98348.c
new file mode 100644
index 00000000000..3c0259f8ca7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr98348.c
@@ -0,0 +1,57 @@
+/* PR target/98348  */
+/* { dg-do compile } */
+/* { dg-options "-mavx512bw -O2" } */
+/* { dg-final { scan-assembler-times "vptestnm\[bwdq\]" "8" } } */
+/* { dg-final { scan-assembler-not "pcmp" } } */
+/* { dg-final { scan-assembler-not "pxor" } } */
+
+
+typedef int v16si __attribute__ ((vector_size(64)));
+typedef short v32hi __attribute__ ((vector_size(64)));
+typedef char v64qi __attribute__ ((vector_size(64)));
+typedef long long v8di __attribute__ ((vector_size(64)));
+typedef unsigned int v16usi __attribute__ ((vector_size(64)));
+typedef unsigned short v32uhi __attribute__ ((vector_size(64)));
+typedef unsigned char v64uqi __attribute__ ((vector_size(64)));
+typedef unsigned long long v8udi __attribute__ ((vector_size(64)));
+
+
+v8di
+compareq(v8di x) {
+  return x == 0;
+}
+
+v16si
+compared(v16si x) {
+  return x == 0;
+}
+
+v32hi
+comparew(v32hi x) {
+  return x == 0;
+}
+
+v64qi
+compareb(v64qi x) {
+  return x == 0;
+}
+
+v8udi
+compareuq(v8udi x) {
+  return x == 0;
+}
+
+v16usi
+compareud(v16usi x) {
+  return x == 0;
+}
+
+v32uhi
+compareuw(v32uhi x) {
+  return x == 0;
+}
+
+v64uqi
+compareub(v64uqi x) {
+  return x == 0;
+}
-- 
2.18.1