[PATCH] D144292: [SLP] Fix infinite loop in isUndefVector.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: RKSimon, vdmitrie, ABataev.
Herald added subscribers: vporpo, StephenFan, hiraditya.
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This fixes an infinite loop if isa<T>(II->getOperand(1)) is true.
Return an all-0 bitvector, which is done along other error paths instead
of the continue, which leads to an infinite loop because Base
is not updated.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144292

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/AArch64/insertelement.ll


Index: llvm/test/Transforms/SLPVectorizer/AArch64/insertelement.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/AArch64/insertelement.ll
+++ llvm/test/Transforms/SLPVectorizer/AArch64/insertelement.ll
@@ -35,3 +35,25 @@
 
 ; Function Attrs: nounwind readnone speculatable willreturn
 declare float @llvm.fabs.f32(float)
+
+
+define <4 x float> @insertelement_poison_lanes(ptr %0) {
+; CHECK-LABEL: @insertelement_poison_lanes(
+; CHECK-NEXT:    [[INS_1:%.*]] = insertelement <4 x float> zeroinitializer, float poison, i64 0
+; CHECK-NEXT:    [[INS_2:%.*]] = insertelement <4 x float> [[INS_1]], float 0.000000e+00, i64 0
+; CHECK-NEXT:    [[GEP_1:%.*]] = getelementptr double, ptr [[TMP0:%.*]], i64 1
+; CHECK-NEXT:    store <2 x double> <double 0.000000e+00, double 1.000000e+00>, ptr [[GEP_1]], align 8
+; CHECK-NEXT:    ret <4 x float> [[INS_2]]
+;
+  %trunc.1 = fptrunc double 0.000000e+00 to float
+  %trunc.2 = fptrunc double 1.000000e+00 to float
+  %ins.1 = insertelement <4 x float> zeroinitializer, float poison, i64 0
+  %ins.2 = insertelement <4 x float> %ins.1, float %trunc.1, i64 0
+  %ext.1 = fpext float %trunc.1 to double
+  %gep.1  = getelementptr double, ptr %0, i64 1
+  store double %ext.1, ptr %gep.1, align 8
+  %ext.2 = fpext float %trunc.2 to double
+  %gep.2 = getelementptr double, ptr %0, i64 2
+  store double %ext.2, ptr %gep.2, align 8
+  ret <4 x float> %ins.2
+}
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -375,7 +375,7 @@
       const Value *Base = V;
       while (auto *II = dyn_cast<InsertElementInst>(Base)) {
         if (isa<T>(II->getOperand(1)))
-          continue;
+          return Res.reset();
         Base = II->getOperand(0);
         std::optional<unsigned> Idx = getInsertIndex(II);
         if (!Idx)


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