[llvm-commits] [llvm] r162120 - in /llvm/trunk: include/llvm/Analysis/MemoryBuiltins.h lib/Analysis/MemoryBuiltins.cpp test/Transforms/InstCombine/objsize.ll

[Nuno Lopes]

Thanks!

----- Original Message ----- 
From: "Benjamin Kramer" <benny.kra at googlemail.com>
To: <llvm-commits at cs.uiuc.edu>
Sent: Friday, August 17, 2012 8:26 PM
Subject: [llvm-commits] [llvm] r162120 - in /llvm/trunk: 
include/llvm/Analysis/MemoryBuiltins.h lib/Analysis/MemoryBuiltins.cpp 
test/Transforms/InstCombine/objsize.ll


> Author: d0k
> Date: Fri Aug 17 14:26:41 2012
> New Revision: 162120
>
> URL: http://llvm.org/viewvc/llvm-project?rev=162120&view=rev
> Log:
> MemoryBuiltins: Properly guard ObjectSizeOffsetVisitor against cycles in 
> the IR.
>
> The previous fix only checked for simple cycles, use a set to catch longer
> cycles too.
>
> Drop the broken check from the ObjectSizeOffsetEvaluator. The 
> BoundsChecking
> pass doesn't have to deal with invalid IR like InstCombine does.
>
> Modified:
>    llvm/trunk/include/llvm/Analysis/MemoryBuiltins.h
>    llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
>    llvm/trunk/test/Transforms/InstCombine/objsize.ll
>
> Modified: llvm/trunk/include/llvm/Analysis/MemoryBuiltins.h
> URL: 
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/MemoryBuiltins.h?rev=162120&r1=162119&r2=162120&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Analysis/MemoryBuiltins.h (original)
> +++ llvm/trunk/include/llvm/Analysis/MemoryBuiltins.h Fri Aug 17 14:26:41 
> 2012
> @@ -146,6 +146,7 @@
>   bool RoundToAlign;
>   unsigned IntTyBits;
>   APInt Zero;
> +  SmallPtrSet<Instruction *, 8> SeenInsts;
>
>   APInt align(APInt Size, uint64_t Align);
>
> @@ -203,7 +204,6 @@
>   const TargetData *TD;
>   LLVMContext &Context;
>   BuilderTy Builder;
> -  ObjectSizeOffsetVisitor Visitor;
>   IntegerType *IntTy;
>   Value *Zero;
>   CacheMapTy CacheMap;
>
> Modified: llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
> URL: 
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryBuiltins.cpp?rev=162120&r1=162119&r2=162120&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/MemoryBuiltins.cpp (original)
> +++ llvm/trunk/lib/Analysis/MemoryBuiltins.cpp Fri Aug 17 14:26:41 2012
> @@ -358,11 +358,16 @@
>
> SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
>   V = V->stripPointerCasts();
> +  if (Instruction *I = dyn_cast<Instruction>(V)) {
> +    // If we have already seen this instruction, bail out. Cycles can 
> happen in
> +    // unreachable code after constant propagation.
> +    if (!SeenInsts.insert(I))
> +      return unknown();
>
> -  if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
> -    return visitGEPOperator(*GEP);
> -  if (Instruction *I = dyn_cast<Instruction>(V))
> +    if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
> +      return visitGEPOperator(*GEP);
>     return visit(*I);
> +  }
>   if (Argument *A = dyn_cast<Argument>(V))
>     return visitArgument(*A);
>   if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
> @@ -371,9 +376,12 @@
>     return visitGlobalVariable(*GV);
>   if (UndefValue *UV = dyn_cast<UndefValue>(V))
>     return visitUndefValue(*UV);
> -  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
> +  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
>     if (CE->getOpcode() == Instruction::IntToPtr)
>       return unknown(); // clueless
> +    if (CE->getOpcode() == Instruction::GetElementPtr)
> +      return visitGEPOperator(cast<GEPOperator>(*CE));
> +  }
>
>   DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " 
> << *V
>         << '\n');
> @@ -473,10 +481,6 @@
> }
>
> 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();
> @@ -510,10 +514,6 @@
> }
>
> SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
> -  // ignore malformed self-looping selects
> -  if (I.getTrueValue() == &I || I.getFalseValue() == &I)
> -    return unknown();
> -
>   SizeOffsetType TrueSide  = compute(I.getTrueValue());
>   SizeOffsetType FalseSide = compute(I.getFalseValue());
>   if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == 
> FalseSide)
> @@ -533,8 +533,7 @@
>
> ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const TargetData *TD,
>                                                      LLVMContext &Context)
> -: TD(TD), Context(Context), Builder(Context, TargetFolder(TD)),
> -Visitor(TD, Context) {
> +: TD(TD), Context(Context), Builder(Context, TargetFolder(TD)) {
>   IntTy = TD->getIntPtrType(Context);
>   Zero = ConstantInt::get(IntTy, 0);
> }
> @@ -559,6 +558,7 @@
> }
>
> SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
> +  ObjectSizeOffsetVisitor Visitor(TD, Context);
>   SizeOffsetType Const = Visitor.compute(V);
>   if (Visitor.bothKnown(Const))
>     return std::make_pair(ConstantInt::get(Context, Const.first),
> @@ -719,10 +719,6 @@
> }
>
> SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst 
> &I) {
> -  // ignore malformed self-looping selects
> -  if (I.getTrueValue() == &I || I.getFalseValue() == &I)
> -    return unknown();
> -
>   SizeOffsetEvalType TrueSide  = compute_(I.getTrueValue());
>   SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
>
>
> Modified: llvm/trunk/test/Transforms/InstCombine/objsize.ll
> URL: 
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/objsize.ll?rev=162120&r1=162119&r2=162120&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/objsize.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/objsize.ll Fri Aug 17 14:26:41 
> 2012
> @@ -247,7 +247,8 @@
>
> ; technically reachable, but this malformed IR may appear as a result of 
> constant propagation
> xpto:
> -  %gep = getelementptr i8* %gep, i32 1
> +  %gep2 = getelementptr i8* %gep, i32 1
> +  %gep = getelementptr i8* %gep2, i32 1
>   %o = call i32 @llvm.objectsize.i32(i8* %gep, i1 true)
> ; CHECK: ret i32 undef
>   ret i32 %o
>
>
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