[llvm] r191644 - ObjectSizeOffsetEvaluator: Don't run into infinite recursion if we have a cyclic GEP.
Benjamin Kramer
benny.kra at googlemail.com
Sun Sep 29 12:39:13 PDT 2013
Author: d0k
Date: Sun Sep 29 14:39:13 2013
New Revision: 191644
URL: http://llvm.org/viewvc/llvm-project?rev=191644&view=rev
Log:
ObjectSizeOffsetEvaluator: Don't run into infinite recursion if we have a cyclic GEP.
Those can occur in dead code. PR17402.
Modified:
llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
llvm/trunk/test/Instrumentation/BoundsChecking/simple.ll
Modified: llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryBuiltins.cpp?rev=191644&r1=191643&r2=191644&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemoryBuiltins.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryBuiltins.cpp Sun Sep 29 14:39:13 2013
@@ -634,13 +634,15 @@ SizeOffsetEvalType ObjectSizeOffsetEvalu
if (Instruction *I = dyn_cast<Instruction>(V))
Builder.SetInsertPoint(I);
- // record the pointers that were handled in this run, so that they can be
- // cleaned later if something fails
- SeenVals.insert(V);
-
// now compute the size and offset
SizeOffsetEvalType Result;
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
+
+ // Record the pointers that were handled in this run, so that they can be
+ // cleaned later if something fails. We also use this set to break cycles that
+ // can occur in dead code.
+ if (!SeenVals.insert(V)) {
+ Result = unknown();
+ } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
Result = visitGEPOperator(*GEP);
} else if (Instruction *I = dyn_cast<Instruction>(V)) {
Result = visit(*I);
Modified: llvm/trunk/test/Instrumentation/BoundsChecking/simple.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Instrumentation/BoundsChecking/simple.ll?rev=191644&r1=191643&r2=191644&view=diff
==============================================================================
--- llvm/trunk/test/Instrumentation/BoundsChecking/simple.ll (original)
+++ llvm/trunk/test/Instrumentation/BoundsChecking/simple.ll Sun Sep 29 14:39:13 2013
@@ -126,3 +126,20 @@ define i64 @f12(i64 %x, i64 %y) nounwind
%4 = load i64* %3, align 8
ret i64 %4
}
+
+; PR17402
+; CHECK-LABEL: @f13
+define void @f13() nounwind {
+entry:
+ br label %alive
+
+dead:
+ ; Self-refential GEPs can occur in dead code.
+ %incdec.ptr = getelementptr inbounds i32* %incdec.ptr, i64 1
+ ; CHECK: %incdec.ptr = getelementptr inbounds i32* %incdec.ptr
+ %l = load i32* %incdec.ptr
+ br label %alive
+
+alive:
+ ret void
+}
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