[llvm] r196508 - SLPVectorizer: An in-tree vectorized entry cannot also be a scalar external use
Arnold Schwaighofer
aschwaighofer at apple.com
Thu Dec 5 07:14:40 PST 2013
Author: arnolds
Date: Thu Dec 5 09:14:40 2013
New Revision: 196508
URL: http://llvm.org/viewvc/llvm-project?rev=196508&view=rev
Log:
SLPVectorizer: An in-tree vectorized entry cannot also be a scalar external use
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
Modified:
llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
llvm/trunk/test/Transforms/SLPVectorizer/X86/external_user.ll
Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=196508&r1=196507&r2=196508&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Thu Dec 5 09:14:40 2013
@@ -564,10 +564,8 @@ void BoUpSLP::buildTree(ArrayRef<Value *
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.
Modified: llvm/trunk/test/Transforms/SLPVectorizer/X86/external_user.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/external_user.ll?rev=196508&r1=196507&r2=196508&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SLPVectorizer/X86/external_user.ll (original)
+++ llvm/trunk/test/Transforms/SLPVectorizer/X86/external_user.ll Thu Dec 5 09:14:40 2013
@@ -59,3 +59,38 @@ for.end:
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
+}
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