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Implement cast.ll::test14/15
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11742 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1378,6 +1378,43 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
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default: break;
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}
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}
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} else { // Not a SetEQ/SetNE
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// If the LHS is a cast from an integral value of the same size,
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if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
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Value *CastOp = Cast->getOperand(0);
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const Type *SrcTy = CastOp->getType();
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unsigned SrcTySize = SrcTy->getPrimitiveSize();
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if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
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SrcTySize == Cast->getType()->getPrimitiveSize()) {
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assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
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"Source and destination signednesses should differ!");
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if (Cast->getType()->isSigned()) {
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// If this is a signed comparison, check for comparisons in the
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// vicinity of zero.
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if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
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// X < 0 => x > 127
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return BinaryOperator::create(Instruction::SetGT, CastOp,
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ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
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else if (I.getOpcode() == Instruction::SetGT &&
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cast<ConstantSInt>(CI)->getValue() == -1)
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// X > -1 => x < 128
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return BinaryOperator::create(Instruction::SetGT, CastOp,
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ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
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} else {
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ConstantUInt *CUI = cast<ConstantUInt>(CI);
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if (I.getOpcode() == Instruction::SetLT &&
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CUI->getValue() == 1ULL << (SrcTySize*8-1))
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// X < 128 => X > -1
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return BinaryOperator::create(Instruction::SetGT, CastOp,
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ConstantSInt::get(SrcTy, -1));
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else if (I.getOpcode() == Instruction::SetGT &&
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CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
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// X > 127 => X < 0
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return BinaryOperator::create(Instruction::SetLT, CastOp,
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Constant::getNullValue(SrcTy));
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}
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}
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}
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}
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// Check to see if we are comparing against the minimum or maximum value...
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