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Implement "strength reduction" of X <= C and X >= C

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llvm-svn: 11735
This commit is contained in:
Chris Lattner 2004-02-23 05:47:48 +00:00
parent c31a2e26ab
commit 51b37305d9
1 changed files with 9 additions and 0 deletions
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9
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1369,6 +1369,15 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
return BinaryOperator::create(Instruction::SetNE, Op0, AddOne(CI));
}
// If we still have a setle or setge instruction, turn it into the
// appropriate setlt or setgt instruction. Since the border cases have
// already been handled above, this requires little checking.
//
if (I.getOpcode() == Instruction::SetLE)
return BinaryOperator::create(Instruction::SetLT, Op0, AddOne(CI));
if (I.getOpcode() == Instruction::SetGE)
return BinaryOperator::create(Instruction::SetGT, Op0, SubOne(CI));
}
// Test to see if the operands of the setcc are casted versions of other