[Analysis] In EmitGEPOffset, use Constant::getUniqueInteger to handle struct indices in vector GEPs.

topperc · topperc · commit 25abd0ebddc2 · 2019-08-27T01:07:37.000Z
We previously called getSplatValue if the index had a vector type,
but getSplatValue returns null for non-splats. This would cause
a nullptr dereference if it wasn't a splat.

Using getUniqueInteger gives us an assert if its a vector type,
but the value isn't a splat. This is what is used in
SelectionDAGBuilder's code that expands GEPs as well.

llvm-svn: 370001
diff --git a/llvm/include/llvm/Analysis/Utils/Local.h b/llvm/include/llvm/Analysis/Utils/Local.h
@@ -51,10 +51,7 @@ Value *EmitGEPOffset(IRBuilderTy *Builder, const DataLayout &DL, User *GEP,
 
       // Handle a struct index, which adds its field offset to the pointer.
       if (StructType *STy = GTI.getStructTypeOrNull()) {
-        if (OpC->getType()->isVectorTy())
-          OpC = OpC->getSplatValue();
-
-        uint64_t OpValue = cast<ConstantInt>(OpC)->getZExtValue();
+        uint64_t OpValue = OpC->getUniqueInteger().getZExtValue();
         Size = DL.getStructLayout(STy)->getElementOffset(OpValue);
 
         if (Size)
