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InstSimplify: Strip pointer casts early. 

llvm-svn: 150694
This commit is contained in:
Benjamin Kramer 2012-02-16 15:03:04 +00:00
parent 9a44b97913
commit 3d27f71f2d
1 changed files with 6 additions and 5 deletions
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11
llvm/lib/Analysis/InstructionSimplify.cpp
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@ -1542,6 +1542,10 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
Type *ITy = GetCompareTy(LHS); // The return type. Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand 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 // icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
// because X could be 0. // because X could be 0.
@ -1591,11 +1595,8 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
// to the case where LHS is a global variable address or null is pointless, // 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 // 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. // the compare, and if only one of them is then we moved it to RHS already.
Value *LHSPtr = LHS->stripPointerCasts(); if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
Value *RHSPtr = RHS->stripPointerCasts(); isa<ConstantPointerNull>(RHS)))
if (isa<AllocaInst>(LHSPtr) && (isa<GlobalValue>(RHSPtr) ||
isa<AllocaInst>(RHSPtr) ||
isa<ConstantPointerNull>(RHSPtr)))
// We already know that LHS != RHS. // We already know that LHS != RHS.
return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred)); return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));