SROA: Check Total Bits of vector type

While Promoting alloca instruction of Vector Type, 
Check total size in bits of its slices too.
If they don't match, don't promote the alloca instruction.

Bug : https://bugs.llvm.org/show_bug.cgi?id=42585

llvm-svn: 372480

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -1888,6 +1888,14 @@ static VectorType *isVectorPromotionViable(Partition &P, const DataLayout &DL) {
   bool HaveCommonEltTy = true;
   auto CheckCandidateType = [&](Type *Ty) {
     if (auto *VTy = dyn_cast<VectorType>(Ty)) {
+      // Return if bitcast to vectors is different for total size in bits.
+      if (!CandidateTys.empty()) {
+        VectorType *V = CandidateTys[0];
+        if (DL.getTypeSizeInBits(VTy) != DL.getTypeSizeInBits(V)) {
+          CandidateTys.clear();
+          return;
+        }
+      }
       CandidateTys.push_back(VTy);
       if (!CommonEltTy)
         CommonEltTy = VTy->getElementType();

llvm/test/Transforms/SROA/vector-promotion-different-size.ll

@@ -0,0 +1,24 @@
+; RUN: opt < %s -sroa -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64"
+
+define <4 x i1> @vector_bitcast() {
+  ; CHECK-LABEL: @vector_bitcast
+  ; CHECK: alloca i1
+
+    %a = alloca <3 x i1>
+    store <3 x i1> <i1 1,i1 0,i1 1>, <3 x i1>* %a
+    %cast = bitcast <3 x i1>* %a to <4 x i1>*
+    %vec = load <4 x i1>, <4 x i1>* %cast
+    ret <4 x i1> %vec
+}
+
+define void @vector_bitcast_2() {
+  ; CHECK-LABEL: @vector_bitcast_2
+  ; CHECK: alloca <32 x i16>
+
+    %"sum$1.host2" = alloca <32 x i16>
+    store <32 x i16> undef, <32 x i16>* %"sum$1.host2"
+    %bc = bitcast <32 x i16>* %"sum$1.host2" to <64 x i16>*
+    %bcl = load <64 x i16>, <64 x i16>* %bc
+    ret void
+}