[llvm-commits] [llvm] r162098 - in /llvm/trunk: lib/Analysis/MemoryBuiltins.cpp test/Transforms/InstCombine/objsize.ll

[Benjamin Kramer]

Author: d0k
Date: Fri Aug 17 09:16:37 2012
New Revision: 162098

URL: http://llvm.org/viewvc/llvm-project?rev=162098&view=rev
Log:
Guard MemoryBuiltins against self-looping GEPs, which can occur in unreachable code due to constant propagation.

Fixes PR13621.

Modified:
    llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
    llvm/trunk/test/Transforms/InstCombine/objsize.ll

Modified: llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryBuiltins.cpp?rev=162098&r1=162097&r2=162098&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemoryBuiltins.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryBuiltins.cpp Fri Aug 17 09:16:37 2012
@@ -473,6 +473,10 @@
 }
 
 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
+  // Ignore self-referencing GEPs, they can occur in unreachable code.
+  if (&GEP == GEP.getPointerOperand())
+    return unknown();
+
   SizeOffsetType PtrData = compute(GEP.getPointerOperand());
   if (!bothKnown(PtrData) || !GEP.hasAllConstantIndices())
     return unknown();

Modified: llvm/trunk/test/Transforms/InstCombine/objsize.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/objsize.ll?rev=162098&r1=162097&r2=162098&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/objsize.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/objsize.ll Fri Aug 17 09:16:37 2012
@@ -238,3 +238,20 @@
 return:
   ret i32 42
 }
+
+; CHECK: @PR13621
+define i32 @PR13621(i1 %bool) nounwind {
+entry:
+  %cond = or i1 %bool, true
+  br i1 %cond, label %return, label %xpto
+
+; technically reachable, but this malformed IR may appear as a result of constant propagation
+xpto:
+  %gep = getelementptr i8* %gep, i32 1
+  %o = call i32 @llvm.objectsize.i32(i8* %gep, i1 true)
+; CHECK: ret i32 undef
+  ret i32 %o
+
+return:
+  ret i32 7
+}