[PATCH] D22878: [LSV] Don't assume that bitcast ops are Instructions.

[Justin Lebar via llvm-commits]

jlebar created this revision.
jlebar added a reviewer: asbirlea.
jlebar added subscribers: arsenm, llvm-commits.
Herald added subscribers: mzolotukhin, jholewinski.

When we ask the builder to create a bitcast on a constant, we get back a
constant, not an instruction.

https://reviews.llvm.org/D22878

Files:
  lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
  test/Transforms/LoadStoreVectorizer/NVPTX/non-instr-bitcast.ll

Index: test/Transforms/LoadStoreVectorizer/NVPTX/non-instr-bitcast.ll
===================================================================
--- /dev/null
+++ test/Transforms/LoadStoreVectorizer/NVPTX/non-instr-bitcast.ll
@@ -0,0 +1,14 @@
+; RUN: opt -mtriple=nvptx64-nvidia-cuda -load-store-vectorizer -S -o - %s | FileCheck %s
+
+; Load from a constant.  This can be vectorized, but shouldn't crash us.
+
+ at global = internal addrspace(1) constant [4 x float] [float 0xBF71111120000000, float 0x3F70410420000000, float 0xBF81111120000000, float 0x3FB5555560000000], align 4
+
+define void @foo() {
+  ; CHECK: load <4 x float>
+  %a = load float, float addrspace(1)* getelementptr inbounds ([4 x float], [4 x float] addrspace(1)* @global, i64 0, i64 0), align 4
+  %b = load float, float addrspace(1)* getelementptr inbounds ([4 x float], [4 x float] addrspace(1)* @global, i64 0, i64 1), align 4
+  %c = load float, float addrspace(1)* getelementptr inbounds ([4 x float], [4 x float] addrspace(1)* @global, i64 0, i64 2), align 4
+  %d = load float, float addrspace(1)* getelementptr inbounds ([4 x float], [4 x float] addrspace(1)* @global, i64 0, i64 3), align 4
+  ret void
+}
Index: lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
===================================================================
--- lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
+++ lib/Transforms/Vectorize/LoadStoreVectorizer.cpp
@@ -970,7 +970,10 @@
   if (VecLoadTy) {
     SmallVector<Instruction *, 16> InstrsToErase;
     SmallVector<Instruction *, 16> InstrsToReorder;
-    InstrsToReorder.push_back(cast<Instruction>(Bitcast));
+    // Bitcast might not be an Instruction, if the value being loaded is a
+    // constant.  In that case, no need to reorder anything.
+    if (Instruction *I = dyn_cast<Instruction>(Bitcast))
+      InstrsToReorder.push_back(I);
 
     unsigned VecWidth = VecLoadTy->getNumElements();
     for (unsigned I = 0, E = Chain.size(); I != E; ++I) {
@@ -997,7 +1000,8 @@
       I->eraseFromParent();
   } else {
     SmallVector<Instruction *, 16> InstrsToReorder;
-    InstrsToReorder.push_back(cast<Instruction>(Bitcast));
+    if (Instruction *I = dyn_cast<Instruction>(Bitcast))
+      InstrsToReorder.push_back(I);
 
     for (unsigned I = 0, E = Chain.size(); I != E; ++I) {
       Value *V = Builder.CreateExtractElement(LI, Builder.getInt32(I));


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