Hi!
On the testcase I've recently fixed I've noticed bad code generation,
we emit
pxor %xmm1, %xmm1
psrld $31, %xmm0
pcmpeqd %xmm1, %xmm0
pcmpeqd %xmm1, %xmm0
or
vpxor %xmm1, %xmm1, %xmm1
vpsrld $31, %xmm0, %xmm0
vpcmpeqd %xmm1, %xmm0, %xmm0
vpcmpeqd %xmm1, %xmm0, %xmm2
rather than
psrad $31, %xmm2
or
vpsrad $31, %xmm1, %xmm2
The following patch fixes that using a combiner splitter.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2023-12-04 Jakub Jelinek <ja...@redhat.com>
PR target/112816
* config/i386/sse.md ((eq (eq (lshiftrt x elt_bits-1) 0) 0)): New
splitter to turn psrld $31; pcmpeq; pcmpeq into psrad $31.
* gcc.target/i386/pr112816.c: New test.
--- gcc/config/i386/sse.md.jj 2023-12-04 09:00:12.722437462 +0100
+++ gcc/config/i386/sse.md 2023-12-04 13:22:38.565833465 +0100
@@ -16614,6 +16614,18 @@ (define_insn_and_split "*ashrv1ti3_inter
DONE;
})
+(define_split
+ [(set (match_operand:VI248_AVX2 0 "register_operand")
+ (eq:VI248_AVX2
+ (eq:VI248_AVX2
+ (lshiftrt:VI248_AVX2
+ (match_operand:VI248_AVX2 1 "register_operand")
+ (match_operand:SI 2 "const_int_operand"))
+ (match_operand:VI248_AVX2 3 "const0_operand"))
+ (match_operand:VI248_AVX2 4 "const0_operand")))]
+ "INTVAL (operands[2]) == GET_MODE_PRECISION (<ssescalarmode>mode) - 1"
+ [(set (match_dup 0) (ashiftrt:VI248_AVX2 (match_dup 1) (match_dup 2)))])
+
(define_expand "rotlv1ti3"
[(set (match_operand:V1TI 0 "register_operand")
(rotate:V1TI
--- gcc/testsuite/gcc.target/i386/pr112816.c.jj 2023-12-04 13:31:51.215061445
+0100
+++ gcc/testsuite/gcc.target/i386/pr112816.c 2023-12-04 13:34:14.008053097
+0100
@@ -0,0 +1,27 @@
+/* PR target/112816 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mno-avx512f -masm=att" } */
+/* { dg-final { scan-assembler-times "psrad\t\\\$31," 2 } } */
+/* { dg-final { scan-assembler-not "pcmpeqd\t" } } */
+
+#define N 4
+struct S { float x[N]; };
+struct T { int x[N]; };
+
+__attribute__((target ("no-sse3,sse2"))) struct T
+foo (struct S x)
+{
+ struct T res;
+ for (int i = 0; i < N; ++i)
+ res.x[i] = __builtin_signbit (x.x[i]) ? -1 : 0;
+ return res;
+}
+
+__attribute__((target ("avx2"))) struct T
+bar (struct S x)
+{
+ struct T res;
+ for (int i = 0; i < N; ++i)
+ res.x[i] = __builtin_signbit (x.x[i]) ? -1 : 0;
+ return res;
+}
Jakub
