Fix the last crasher I've gotten a reproduction for in SROA. This one

from the dragonegg build bots when we turned on the full version of the
pass. Included a much reduced test case for this pesky bug, despite
bugpoint's uncooperative behavior.

Also, I audited all the similar code I could find and didn't spot any
other cases where this mistake cropped up.

llvm-svn: 164178

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -1487,6 +1487,8 @@ static Value *getNaturalGEPWithOffset(IRBuilder<> &IRB, const TargetData &TD,
     return 0;
 
   Type *ElementTy = Ty->getElementType();
+  if (!ElementTy->isSized())
+    return 0; // We can't GEP through an unsized element.
   APInt ElementSize(Offset.getBitWidth(), TD.getTypeAllocSize(ElementTy));
   if (ElementSize == 0)
     return 0; // Zero-length arrays can't help us build a natural GEP.

llvm/test/Transforms/SROA/basictest.ll

@@ -754,3 +754,23 @@ entry:
   ret void
 }
 
+%opaque = type opaque
+
+define i32 @test19(%opaque* %x) {
+; This input will cause us to try to compute a natural GEP when rewriting
+; pointers in such a way that we try to GEP through the opaque type. Previously,
+; a check for an unsized type was missing and this crashed. Ensure it behaves
+; reasonably now.
+; CHECK: @test19
+; CHECK-NOT: alloca
+; CHECK: ret i32 undef
+
+entry:
+  %a = alloca { i64, i8* }
+  %cast1 = bitcast %opaque* %x to i8*
+  %cast2 = bitcast { i64, i8* }* %a to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %cast2, i8* %cast1, i32 16, i32 1, i1 false)
+  %gep = getelementptr inbounds { i64, i8* }* %a, i32 0, i32 0
+  %val = load i64* %gep
+  ret i32 undef
+}