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* [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR
@ 2020-06-18 10:11 marxin at gcc dot gnu.org
2020-06-18 10:12 ` [Bug tree-optimization/95739] " marxin at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: marxin at gcc dot gnu.org @ 2020-06-18 10:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95739
Bug ID: 95739
Summary: [11 Regression] Unordered comparison and VEC_COND_EXPR
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: marxin at gcc dot gnu.org
CC: rguenth at gcc dot gnu.org
Target Milestone: ---
The following is a fallout of
r11-1445-g502d63b6d6141597bb18fd23c87736a1b384cf8f but it seems to me a latent
issue:
$ cat pr50310.c
double s1[4], s2[4], s3[64];
int
main ()
{
s1[0] = __builtin_nan ("");
s1[1] = 6.0;
s1[2] = 6.0;
s1[3] = 6.0;
s2[0] = 5.0;
s2[1] = 5.0;
s2[2] = 5.0;
s2[3] = 5.0;
asm volatile ("" : : : "memory");
for (int i = 0; i < 4; i++)
s3[i] = __builtin_isgreater (s1[i], s2[i]) ? -1.0 : 0.0;
if (s3[1] != -1.0)
__builtin_abort ();
return 0;
}
$ gcc pr50310.c -O3 -ffloat-store && ./a.out
Aborted (core dumped)
The thing is that we newly generate:
--- good 2020-06-18 12:08:56.901799621 +0200
+++ bad 2020-06-18 12:08:54.137825794 +0200
@@ -1,39 +1,43 @@
-;; Function main (main, funcdef_no=0, decl_uid=1937, cgraph_uid=1,
symbol_order=3) (executed once)
+;; Function main (main, funcdef_no=0, decl_uid=1933, cgraph_uid=1,
symbol_order=3) (executed once)
main ()
{
vector(2) double vect_iftmp.11;
vector(2) double vect__2.10;
vector(2) double vect__1.7;
+ vector(2) <signed-boolean:64> _4;
double _14;
+ vector(2) <signed-boolean:64> _43;
<bb 2> [local count: 214748371]:
MEM <vector(2) double> [(double *)&s1] = { Nan, 6.0e+0 };
MEM <vector(2) double> [(double *)&s1 + 16B] = { 6.0e+0, 6.0e+0 };
MEM <vector(2) double> [(double *)&s2] = { 5.0e+0, 5.0e+0 };
MEM <vector(2) double> [(double *)&s2 + 16B] = { 5.0e+0, 5.0e+0 };
__asm__ __volatile__("" : : : "memory");
vect__1.7_5 = MEM <vector(2) double> [(double *)&s1];
vect__2.10_19 = MEM <vector(2) double> [(double *)&s2];
- vect_iftmp.11_4 = VEC_COND_EXPR <vect__1.7_5 u<= vect__2.10_19, { 0.0, 0.0
}, { -1.0e+0, -1.0e+0 }>;
- MEM <vector(2) double> [(double *)&s3] = vect_iftmp.11_4;
+ _4 = vect__1.7_5 u<= vect__2.10_19;
+ vect_iftmp.11_33 = .VCOND (vect__1.7_5, vect__2.10_19, { 0.0, 0.0 }, {
-1.0e+0, -1.0e+0 }, 117);
+ MEM <vector(2) double> [(double *)&s3] = vect_iftmp.11_33;
vect__1.7_37 = MEM <vector(2) double> [(double *)&s1 + 16B];
vect__2.10_40 = MEM <vector(2) double> [(double *)&s2 + 16B];
- vect_iftmp.11_43 = VEC_COND_EXPR <vect__1.7_37 u<= vect__2.10_40, { 0.0, 0.0
}, { -1.0e+0, -1.0e+0 }>;
- MEM <vector(2) double> [(double *)&s3 + 16B] = vect_iftmp.11_43;
- _14 = BIT_FIELD_REF <vect_iftmp.11_4, 64, 64>;
+ _43 = vect__1.7_37 u<= vect__2.10_40;
+ vect_iftmp.11_44 = .VCOND (vect__1.7_37, vect__2.10_40, { 0.0, 0.0 }, {
-1.0e+0, -1.0e+0 }, 117);
+ MEM <vector(2) double> [(double *)&s3 + 16B] = vect_iftmp.11_44;
+ _14 = BIT_FIELD_REF <vect_iftmp.11_33, 64, 64>;
if (_14 != -1.0e+0)
goto <bb 3>; [0.00%]
else
goto <bb 4>; [100.00%]
<bb 3> [count: 0]:
__builtin_abort ();
<bb 4> [local count: 214748368]:
return 0;
}
Looking at the assembly the comparison is somehow gone:
diff -u good.s bad.s
--- good.s 2020-06-18 12:09:52.385274181 +0200
+++ bad.s 2020-06-18 12:09:54.013258763 +0200
@@ -19,31 +19,14 @@
movapd .LC2(%rip), %xmm0
movaps %xmm0, s2(%rip)
movaps %xmm0, s2+16(%rip)
- movapd s2(%rip), %xmm3
- movapd s1(%rip), %xmm2
- movapd .LC3(%rip), %xmm1
- movapd s2+16(%rip), %xmm6
- movaps %xmm3, 48(%rsp)
- movapd 48(%rsp), %xmm0
- movapd s1+16(%rip), %xmm5
- movaps %xmm2, 32(%rsp)
- cmpnltpd 32(%rsp), %xmm0
- movaps %xmm6, 80(%rsp)
- movaps %xmm5, 64(%rsp)
- andnpd %xmm1, %xmm0
- movaps %xmm0, 16(%rsp)
- movapd 80(%rsp), %xmm0
- movapd 16(%rsp), %xmm4
- cmpnltpd 64(%rsp), %xmm0
- movaps %xmm4, s3(%rip)
- andnpd %xmm1, %xmm0
- movaps %xmm0, 96(%rsp)
- movsd 24(%rsp), %xmm0
- movapd 96(%rsp), %xmm7
+ movsd 56(%rsp), %xmm0
+ movapd 48(%rsp), %xmm1
+ movapd 96(%rsp), %xmm2
movsd %xmm0, 8(%rsp)
movsd .LC4(%rip), %xmm0
ucomisd 8(%rsp), %xmm0
- movaps %xmm7, s3+16(%rip)
+ movaps %xmm1, s3(%rip)
+ movaps %xmm2, s3+16(%rip)
jp .L4
comisd 8(%rsp), %xmm0
jne .L4
@@ -107,16 +90,10 @@
.long 1075052544
.long 0
.long 1075052544
- .align 16
-.LC3:
- .long 0
- .long -1074790400
- .long 0
- .long -1074790400
.section .rodata.cst8,"aM",@progbits,8
.align 8
.LC4:
.long 0
.long -1074790400
- .ident "GCC: (SUSE Linux) 10.1.1 20200507 [revision
dd38686d9c810cecbaa80bb82ed91caaa58ad635]"
+ .ident "GCC: (GNU) 11.0.0 20200618 (experimental)"
.section .note.GNU-stack,"",@progbits
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/95739] [11 Regression] Unordered comparison and VEC_COND_EXPR
2020-06-18 10:11 [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR marxin at gcc dot gnu.org
@ 2020-06-18 10:12 ` marxin at gcc dot gnu.org
2020-06-18 11:37 ` [Bug middle-end/95739] " rguenth at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: marxin at gcc dot gnu.org @ 2020-06-18 10:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95739
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Last reconfirmed| |2020-06-18
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
@Richi: Do you have a hint what went wrong?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/95739] [11 Regression] Unordered comparison and VEC_COND_EXPR
2020-06-18 10:11 [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR marxin at gcc dot gnu.org
2020-06-18 10:12 ` [Bug tree-optimization/95739] " marxin at gcc dot gnu.org
@ 2020-06-18 11:37 ` rguenth at gcc dot gnu.org
2020-06-18 12:47 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-06-18 11:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95739
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|tree-optimization |middle-end
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Status|NEW |ASSIGNED
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, the vectorizer emits
vect_cst__41 = { 0.0, 0.0 };
vect_cst__42 = { -1.0e+0, -1.0e+0 };
...
vect__1.7_37 = MEM <vector(2) double> [(double *)vectp_s1.5_35];
_1 = s1[i_23];
vect__2.10_40 = MEM <vector(2) double> [(double *)vectp_s2.8_38];
_2 = s2[i_23];
_43 = vect__1.7_37 u<= vect__2.10_40;
vect_iftmp.11_44 = VEC_COND_EXPR <_43, vect_cst__41, vect_cst__42>;
iftmp.0_5 = _1 u<= _2 ? 0.0 : -1.0e+0;
but this is __builtin__isgreaterequal (s1[i], s2[i]) ? 0:0 : -1.0; already
this way from if-conversion it seems. Before we have
if (_1 u<= _2)
goto <bb 10>; [50.00%]
else
goto <bb 4>; [50.00%]
<bb 10> [local count: 429496729]:
goto <bb 5>; [100.00%]
<bb 4> [local count: 429496728]:
<bb 5> [local count: 858993457]:
# iftmp.0_5 = PHI <-1.0e+0(4), 0.0(10)>
And even .original:
s3[i] = s1[i] u<= s2[i] ? 0.0 : -1.0e+0;
but that's the inverted condition plus swapped which should be u>=!?
Seemingly this is generated from
/* !A ? B : C -> A ? C : B. */
(simplify
(cnd (logical_inverted_value truth_valued_p@0) @1 @2)
(cnd @0 @2 @1)))
fed by !(s1[i] u<= s2[i]) ? -1. : 0. Hmm, which looks OK.
later the backend via ix86_prepare_sse_fp_compare_args correctly (!?)
swaps operands of the compare to s2[i] u>= s1[i].
Now somewhere things go wrong and the __builtin_isgreater vanishes completely,
leaving us with uninitialized stack slots:
main:
.LFB0:
.cfi_startproc
subq $120, %rsp
.cfi_def_cfa_offset 128
movapd .LC0(%rip), %xmm0
movaps %xmm0, s1(%rip)
movapd .LC1(%rip), %xmm0
movaps %xmm0, s1+16(%rip)
movapd .LC2(%rip), %xmm0
movaps %xmm0, s2(%rip)
movaps %xmm0, s2+16(%rip)
movsd 56(%rsp), %xmm0
movapd 48(%rsp), %xmm1
movapd 96(%rsp), %xmm2
movsd %xmm0, 8(%rsp)
movsd .LC4(%rip), %xmm0
ucomisd 8(%rsp), %xmm0
movaps %xmm1, s3(%rip)
movaps %xmm2, s3+16(%rip)
I guess the issue is
31: r104:V2DF=unge(r103:V2DF,[r77:DI-0x60])
32: r101:V2DF=~r104:V2DF&r102:V2DF
33: r105:DI=`s3'
34: r106:V2DF=[r77:DI-0x40]
35: [r105:DI]=r106:V2DF
look at how we compute the result into r101 but then use [r77:D1-0x40]
as source for the store. When I trace expand_vect_cond_optab_fn
I see 'target' is expanded to
(mem/c:V2DF (plus:DI (reg/f:DI 77 virtual-stack-vars)
(const_int -64 [0xffffffffffffffc0])) [1 vect_iftmp.11+0 S16 A128])
but we don't check whether ops[0].value matches target after expand_insn
and fail to move it there.
testing patch.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/95739] [11 Regression] Unordered comparison and VEC_COND_EXPR
2020-06-18 10:11 [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR marxin at gcc dot gnu.org
2020-06-18 10:12 ` [Bug tree-optimization/95739] " marxin at gcc dot gnu.org
2020-06-18 11:37 ` [Bug middle-end/95739] " rguenth at gcc dot gnu.org
@ 2020-06-18 12:47 ` cvs-commit at gcc dot gnu.org
2020-06-18 12:47 ` rguenth at gcc dot gnu.org
2020-06-18 12:48 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-06-18 12:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95739
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:eccc3d432669ba272229d49f015cb986df21eb0a
commit r11-1510-geccc3d432669ba272229d49f015cb986df21eb0a
Author: Richard Biener <rguenther@suse.de>
Date: Thu Jun 18 14:45:03 2020 +0200
middle-end/95739 - fix vector condition IFN expansion
This fixes the omission of moving the expansion result to the
target.
2020-06-18 Richard Biener <rguenther@suse.de>
PR middle-end/95739
* internal-fn.c (expand_vect_cond_optab_fn): Move the result
to the target if necessary.
(expand_vect_cond_mask_optab_fn): Likewise.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/95739] [11 Regression] Unordered comparison and VEC_COND_EXPR
2020-06-18 10:11 [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR marxin at gcc dot gnu.org
` (2 preceding siblings ...)
2020-06-18 12:47 ` cvs-commit at gcc dot gnu.org
@ 2020-06-18 12:47 ` rguenth at gcc dot gnu.org
2020-06-18 12:48 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-06-18 12:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95739
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/95739] [11 Regression] Unordered comparison and VEC_COND_EXPR
2020-06-18 10:11 [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR marxin at gcc dot gnu.org
` (3 preceding siblings ...)
2020-06-18 12:47 ` rguenth at gcc dot gnu.org
@ 2020-06-18 12:48 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-06-18 12:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95739
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |11.0
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-06-18 10:11 [Bug tree-optimization/95739] New: [11 Regression] Unordered comparison and VEC_COND_EXPR marxin at gcc dot gnu.org
2020-06-18 10:12 ` [Bug tree-optimization/95739] " marxin at gcc dot gnu.org
2020-06-18 11:37 ` [Bug middle-end/95739] " rguenth at gcc dot gnu.org
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