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i386: Fix emit_reduc_half on V{64Q,32H}Imode [PR94500] 

The following testcase is miscompiled in 8.x, because emit_reduc_half is
prepared to handle for 512-bit modes only i equal to 512, 256, 128 and 64.
V32HImode also needs i equal to 32 and V64QImode i equal to 32 and 16,
but emit_reduc_half in that case performs a redundant permutation exactly
like i == 32.  In 9+ the testcase works because Richard in r9-3393
changed the reduc_* expanders so that they actually don't call
ix86_expand_reduc on 512-bit modes, but only 128-bit ones.

The patch fixes emit_reduc_half to handle also i of 32 and 16 similarly to
how V32QImode/V16HImode are handled for AVX2.  I think it shouldn't hurt
to fix the function even on the trunk and 9 branch even when nothing uses
it ATM.

2020-04-07  Jakub Jelinek  <jakub@redhat.com>

	PR target/94500
	* config/i386/i386.c (emit_reduc_half): For V{64QI,32HI}mode
	handle i < 64 using avx512bw_lshrv4ti3.  Formatting fixes.

	* gcc.target/i386/avx512bw-pr94500.c: New test.
This commit is contained in:
Jakub Jelinek 2020-04-07 08:27:49 +02:00
parent af1c291f50
commit 1168240fbe
4 changed files with 76 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2020-04-07 Jakub Jelinek <jakub@redhat.com>
PR target/94500
* config/i386/i386.c (emit_reduc_half): For V{64QI,32HI}mode
handle i < 64 using avx512bw_lshrv4ti3. Formatting fixes.
2020-04-02 Martin Jambor <mjambor@suse.cz>
PR tree-optimization/93435

66
gcc/config/i386/i386.c
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@ -44150,43 +44150,51 @@ emit_reduc_half (rtx dest, rtx src, int i)
break;
case E_V64QImode:
case E_V32HImode:
if (i < 64)
{
d = gen_reg_rtx (V4TImode);
tem = gen_avx512bw_lshrv4ti3 (d, gen_lowpart (V4TImode, src),
GEN_INT (i / 2));
break;
}
/* FALLTHRU */
case E_V16SImode:
case E_V16SFmode:
case E_V8DImode:
case E_V8DFmode:
if (i > 128)
tem = gen_avx512f_shuf_i32x4_1 (gen_lowpart (V16SImode, dest),
gen_lowpart (V16SImode, src),
gen_lowpart (V16SImode, src),
GEN_INT (0x4 + (i == 512 ? 4 : 0)),
GEN_INT (0x5 + (i == 512 ? 4 : 0)),
GEN_INT (0x6 + (i == 512 ? 4 : 0)),
GEN_INT (0x7 + (i == 512 ? 4 : 0)),
GEN_INT (0xC), GEN_INT (0xD),
GEN_INT (0xE), GEN_INT (0xF),
GEN_INT (0x10), GEN_INT (0x11),
GEN_INT (0x12), GEN_INT (0x13),
GEN_INT (0x14), GEN_INT (0x15),
GEN_INT (0x16), GEN_INT (0x17));
gen_lowpart (V16SImode, src),
gen_lowpart (V16SImode, src),
GEN_INT (0x4 + (i == 512 ? 4 : 0)),
GEN_INT (0x5 + (i == 512 ? 4 : 0)),
GEN_INT (0x6 + (i == 512 ? 4 : 0)),
GEN_INT (0x7 + (i == 512 ? 4 : 0)),
GEN_INT (0xC), GEN_INT (0xD),
GEN_INT (0xE), GEN_INT (0xF),
GEN_INT (0x10), GEN_INT (0x11),
GEN_INT (0x12), GEN_INT (0x13),
GEN_INT (0x14), GEN_INT (0x15),
GEN_INT (0x16), GEN_INT (0x17));
else
tem = gen_avx512f_pshufd_1 (gen_lowpart (V16SImode, dest),
gen_lowpart (V16SImode, src),
GEN_INT (i == 128 ? 0x2 : 0x1),
GEN_INT (0x3),
GEN_INT (0x3),
GEN_INT (0x3),
GEN_INT (i == 128 ? 0x6 : 0x5),
GEN_INT (0x7),
GEN_INT (0x7),
GEN_INT (0x7),
GEN_INT (i == 128 ? 0xA : 0x9),
GEN_INT (0xB),
GEN_INT (0xB),
GEN_INT (0xB),
GEN_INT (i == 128 ? 0xE : 0xD),
GEN_INT (0xF),
GEN_INT (0xF),
GEN_INT (0xF));
gen_lowpart (V16SImode, src),
GEN_INT (i == 128 ? 0x2 : 0x1),
GEN_INT (0x3),
GEN_INT (0x3),
GEN_INT (0x3),
GEN_INT (i == 128 ? 0x6 : 0x5),
GEN_INT (0x7),
GEN_INT (0x7),
GEN_INT (0x7),
GEN_INT (i == 128 ? 0xA : 0x9),
GEN_INT (0xB),
GEN_INT (0xB),
GEN_INT (0xB),
GEN_INT (i == 128 ? 0xE : 0xD),
GEN_INT (0xF),
GEN_INT (0xF),
GEN_INT (0xF));
break;
default:
gcc_unreachable ();

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2020-04-07 Jakub Jelinek <jakub@redhat.com>
PR target/94500
* gcc.target/i386/avx512bw-pr94500.c: New test.
2020-04-06 Fritz Reese <foreese@gcc.gnu.org>
Backport from master.

28
gcc/testsuite/gcc.target/i386/avx512bw-pr94500.c Normal file
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@ -0,0 +1,28 @@
/* PR target/94500 */
/* { dg-do run { target avx512bw } } */
/* { dg-options "-O3 -mavx512bw -mprefer-vector-width=512" } */
#define AVX512BW
#include "avx512f-helper.h"
__attribute__((noipa)) signed char
foo (signed char *p)
{
signed char r = 0;
int i;
for (i = 0; i < 256; i++)
if (p[i] > r) r = p[i];
return r;
}
signed char buf[256];
static void
TEST (void)
{
int i;
for (i = 0; i < 256; i++)
buf[i] = i - 128;
if (foo (buf) != 127)
abort ();
}