[llvm-commits] [llvm] r122772 - in /llvm/trunk: lib/Analysis/BasicAliasAnalysis.cpp test/Analysis/BasicAA/global-size.ll

[Chris Lattner]

Author: lattner
Date: Mon Jan  3 15:03:33 2011
New Revision: 122772

URL: http://llvm.org/viewvc/llvm-project?rev=122772&view=rev
Log:
fix rdar://8813415 - a miscompilation of 164.gzip that loop-idiom
exposed.  It turns out to be a latent bug in basicaa, scary.

Modified:
    llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
    llvm/trunk/test/Analysis/BasicAA/global-size.ll

Modified: llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp?rev=122772&r1=122771&r2=122772&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp Mon Jan  3 15:03:33 2011
@@ -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())

Modified: llvm/trunk/test/Analysis/BasicAA/global-size.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BasicAA/global-size.ll?rev=122772&r1=122771&r2=122772&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/BasicAA/global-size.ll (original)
+++ llvm/trunk/test/Analysis/BasicAA/global-size.ll Mon Jan  3 15:03:33 2011
@@ -16,3 +16,25 @@
 ; CHECK: ret i16 0
 }
 
+; Cannot know anything about the size of this global.
+; rdar://8813415
+ at 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
+}
+