SROA: The alloca type isn't a candidate promotion type for vectors

The alloca's type is irrelevant, only those types which are used in a
load or store of the exact size of the slice should be considered.

This manifested as an assertion failure when we compared the various
types: we had a size mismatch.

This fixes PR21480.

llvm-svn: 222499

3 files changed, 28 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 1bbaaf34603..d37eac56d51 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -394,6 +394,13 @@ static BinaryOperator *LowerNegateToMultiply(Instruction *Neg) {
   BinaryOperator *Res = CreateMul(Neg->getOperand(1), NegOne, "", Neg, Neg);
   Neg->setOperand(1, Constant::getNullValue(Ty)); // Drop use of op.
   Res->takeName(Neg);
+  if (Ty->isIntegerTy()) {
+    bool NSW = cast<BinaryOperator>(Neg)->hasNoSignedWrap();
+    bool NUW = cast<BinaryOperator>(Neg)->hasNoUnsignedWrap();
+    if (NSW || NUW)
+      Res->setHasNoSignedWrap(true);
+    Res->setHasNoUnsignedWrap(NUW);
+  }
   Neg->replaceAllUsesWith(Res);
   Res->setDebugLoc(Neg->getDebugLoc());
   return Res;
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 6135114eb17..f9ebd75ec71 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1691,7 +1691,7 @@ isVectorPromotionViableForSlice(const DataLayout &DL, uint64_t SliceBeginOffset,
 /// don't want to do the rewrites unless we are confident that the result will
 /// be promotable, so we have an early test here.
 static VectorType *
-isVectorPromotionViable(const DataLayout &DL, Type *AllocaTy,
+isVectorPromotionViable(const DataLayout &DL,
                         uint64_t SliceBeginOffset, uint64_t SliceEndOffset,
                         AllocaSlices::const_range Slices,
                         ArrayRef<AllocaSlices::iterator> SplitUses) {
@@ -1709,7 +1709,6 @@ isVectorPromotionViable(const DataLayout &DL, Type *AllocaTy,
         HaveCommonEltTy = false;
     }
   };
-  CheckCandidateType(AllocaTy);
   // Consider any loads or stores that are the exact size of the slice.
   for (const auto &S : Slices)
     if (S.beginOffset() == SliceBeginOffset &&
@@ -3213,7 +3212,7 @@ bool SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
   VectorType *VecTy =
       IsIntegerPromotable
           ? nullptr
-          : isVectorPromotionViable(*DL, SliceTy, BeginOffset, EndOffset,
+          : isVectorPromotionViable(*DL, BeginOffset, EndOffset,
                                     AllocaSlices::const_range(B, E), SplitUses);
   if (VecTy)
     SliceTy = VecTy;
diff --git a/llvm/test/Transforms/SROA/vector-promotion.ll b/llvm/test/Transforms/SROA/vector-promotion.ll
index 830a22a37dc..c20c6352e09 100644
--- a/llvm/test/Transforms/SROA/vector-promotion.ll
+++ b/llvm/test/Transforms/SROA/vector-promotion.ll
@@ -604,3 +604,22 @@ entry:
   ret <2 x float> %result
 ; CHECK-NEXT: ret <2 x float> %[[V4]]
 }
+
+define <4 x float> @test12() {
+; CHECK-LABEL: @test12(
+  %a = alloca <3 x i32>, align 16
+; CHECK-NOT: alloca
+
+  %cast1 = bitcast <3 x i32>* %a to <4 x i32>*
+  store <4 x i32> undef, <4 x i32>* %cast1, align 16
+; CHECK-NOT: store
+
+  %cast2 = bitcast <3 x i32>* %a to <3 x float>*
+  %cast3 = bitcast <3 x float>* %cast2 to <4 x float>*
+  %vec = load <4 x float>* %cast3
+; CHECK-NOT: load
+
+; CHECK:      %[[ret:.*]] = bitcast <4 x i32> undef to <4 x float>
+; CHECK-NEXT: ret <4 x float> %[[ret]]
+  ret <4 x float> %vec
+}