fix rdar://8813415 - a miscompilation of 164.gzip that loop-idiom
exposed. It turns out to be a latent bug in basicaa, scary.
llvm-svn: 122772
diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 1a526fc..8e0637a 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -103,6 +103,8 @@
const TargetData &TD) {
const Type *AccessTy;
if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+ if (!GV->hasDefinitiveInitializer())
+ return false;
AccessTy = GV->getType()->getElementType();
} else if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
if (!AI->isArrayAllocation())
diff --git a/llvm/test/Analysis/BasicAA/global-size.ll b/llvm/test/Analysis/BasicAA/global-size.ll
index 810322e..a7e5aab 100644
--- a/llvm/test/Analysis/BasicAA/global-size.ll
+++ b/llvm/test/Analysis/BasicAA/global-size.ll
@@ -16,3 +16,25 @@
; CHECK: ret i16 0
}
+; Cannot know anything about the size of this global.
+; rdar://8813415
+@window = external global [0 x i8]
+
+; CHECK: @test2
+define i8 @test2(i32 %tmp79, i32 %w.2, i32 %indvar89) nounwind {
+ %tmp92 = add i32 %tmp79, %indvar89
+ %arrayidx412 = getelementptr [0 x i8]* @window, i32 0, i32 %tmp92
+ %tmp93 = add i32 %w.2, %indvar89
+ %arrayidx416 = getelementptr [0 x i8]* @window, i32 0, i32 %tmp93
+
+ %A = load i8* %arrayidx412, align 1
+ store i8 4, i8* %arrayidx416, align 1
+
+ %B = load i8* %arrayidx412, align 1
+ %C = sub i8 %A, %B
+ ret i8 %C
+
+; CHECK: %B = load i8
+; CHECK: ret i8 %C
+}
+