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SLPVectorizer: An in-tree vectorized entry cannot also be a scalar external use

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We were creating external uses for scalar values in MustGather entries that also
had a ScalarToTreeEntry (they also are present in a vectorized tuple). This
meant we would keep a value 'alive' as a scalar and vectorized causing havoc.
This is not necessary because when we create a MustGather vector we explicitly
create external uses entries for the insertelement instructions of the
MustGather vector elements.

Fixes PR18129.

radar://15582184

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196508 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Arnold Schwaighofer 2013-12-05 15:14:40 +00:00
parent 64abf5b441
commit 9e0807cb61
2 changed files with 36 additions and 5 deletions
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6
lib/Transforms/Vectorize/SLPVectorizer.cpp
View File

@ -564,10 +564,8 @@ void BoUpSLP::buildTree(ArrayRef<Value *> Roots, ValueSet *Rdx) {
UE = Scalar->use_end(); User != UE; ++User) {
DEBUG(dbgs() << "SLP: Checking user:" << **User << ".\n");
bool Gathered = MustGather.count(*User);
// Skip in-tree scalars that become vectors.
if (ScalarToTreeEntry.count(*User) && !Gathered) {
if (ScalarToTreeEntry.count(*User)) {
DEBUG(dbgs() << "SLP: \tInternal user will be removed:" <<
**User << ".\n");
int Idx = ScalarToTreeEntry[*User]; (void) Idx;
@ -1641,8 +1639,6 @@ Value *BoUpSLP::vectorizeTree() {
for (Value::use_iterator User = Scalar->use_begin(),
UE = Scalar->use_end(); User != UE; ++User) {
DEBUG(dbgs() << "SLP: \tvalidating user:" << **User << ".\n");
assert(!MustGather.count(*User) &&
"Replacing gathered value with undef");
assert((ScalarToTreeEntry.count(*User) ||
// It is legal to replace the reduction users by undef.

35
test/Transforms/SLPVectorizer/X86/external_user.ll
View File

@ -59,3 +59,38 @@ for.end: ; preds = %for.body
ret double %mul3
}
; A need-to-gather entry cannot be an external use of the scalar element.
; Instead the insertelement instructions of the need-to-gather entry are the
; external users.
; This test would assert because we would keep the scalar fpext and fadd alive.
; PR18129
; CHECK-LABEL: needtogather
define i32 @needtogather(double *noalias %a, i32 *noalias %b, float * noalias %c,
i32 * noalias %d) {
entry:
%0 = load i32* %d, align 4
%conv = sitofp i32 %0 to float
%1 = load float* %c
%sub = fsub float 0.000000e+00, %1
%mul = fmul float %sub, 0.000000e+00
%add = fadd float %conv, %mul
%conv1 = fpext float %add to double
%sub3 = fsub float 1.000000e+00, %1
%mul4 = fmul float %sub3, 0.000000e+00
%add5 = fadd float %conv, %mul4
%conv6 = fpext float %add5 to double
%tobool = fcmp une float %add, 0.000000e+00
br i1 %tobool, label %if.then, label %if.end
if.then:
br label %if.end
if.end:
%storemerge = phi double [ %conv6, %if.then ], [ %conv1, %entry ]
%e.0 = phi double [ %conv1, %if.then ], [ %conv6, %entry ]
store double %storemerge, double* %a, align 8
%conv7 = fptosi double %e.0 to i32
store i32 %conv7, i32* %b, align 4
ret i32 undef
}