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Revert "InstSimplify: Strip pointer casts early." 

Turns out this isn't safe, because the code below depends on LHS and RHS having
the same type.

llvm-svn: 150695
This commit is contained in:
Benjamin Kramer 2012-02-16 15:19:59 +00:00
parent 3d27f71f2d
commit 08f18b1b74
1 changed files with 5 additions and 6 deletions
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11
llvm/lib/Analysis/InstructionSimplify.cpp
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@ -1542,10 +1542,6 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand type.
// Remove pointer casts that don't change the value.
LHS = LHS->stripPointerCasts();
RHS = RHS->stripPointerCasts();
// icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
// because X could be 0.
@ -1595,8 +1591,11 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
// to the case where LHS is a global variable address or null is pointless,
// since if both LHS and RHS are constants then we already constant folded
// the compare, and if only one of them is then we moved it to RHS already.
if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
isa<ConstantPointerNull>(RHS)))
Value *LHSPtr = LHS->stripPointerCasts();
Value *RHSPtr = RHS->stripPointerCasts();
if (isa<AllocaInst>(LHSPtr) && (isa<GlobalValue>(RHSPtr) ||
isa<AllocaInst>(RHSPtr) ||
isa<ConstantPointerNull>(RHSPtr)))
// We already know that LHS != RHS.
return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));