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constant fold nasty constant expressions formed by llvm-gcc,

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wrapping up PR3351.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92410 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-01-02 01:22:23 +00:00
parent 0b178e25c4
commit 79fa3cf451
1 changed files with 16 additions and 3 deletions
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19
lib/Analysis/ConstantFolding.cpp
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@ -718,14 +718,13 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
switch (Opcode) {
default: return 0;
case Instruction::ICmp:
case Instruction::FCmp: assert(0 && "Invalid for compares");
case Instruction::Call:
if (Function *F = dyn_cast<Function>(Ops[0]))
if (canConstantFoldCallTo(F))
return ConstantFoldCall(F, Ops+1, NumOps-1);
return 0;
case Instruction::ICmp:
case Instruction::FCmp:
llvm_unreachable("This function is invalid for compares: no predicate specified");
case Instruction::PtrToInt:
// If the input is a inttoptr, eliminate the pair. This requires knowing
// the width of a pointer, so it can't be done in ConstantExpr::getCast.
@ -877,6 +876,20 @@ Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
CE1->getOperand(0), TD);
}
}
// icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0)
// icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0)
if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) &&
CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) {
Constant *LHS =
ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0), Ops1,TD);
Constant *RHS =
ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(1), Ops1,TD);
unsigned OpC =
Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
Constant *Ops[] = { LHS, RHS };
return ConstantFoldInstOperands(OpC, LHS->getType(), Ops, 2, TD);
}
}
return ConstantExpr::getCompare(Predicate, Ops0, Ops1);