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.
