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fold away (x <= cst) earlier, allowing us to not have to

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handle them in some code.

llvm-svn: 53445
This commit is contained in:
Chris Lattner 2008-07-11 05:08:55 +00:00
parent 16b8ae98c1
commit d1198896ae
1 changed files with 68 additions and 103 deletions
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171
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -5251,6 +5251,29 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
return new ICmpInst(I.getPredicate(), A, B);
}
// If we have a icmp le or icmp ge instruction, turn it into the appropriate
// icmp lt or icmp gt instruction. This allows us to rely on them being
// folded in the code below.
switch (I.getPredicate()) {
default: break;
case ICmpInst::ICMP_ULE:
if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
case ICmpInst::ICMP_SLE:
if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
case ICmpInst::ICMP_UGE:
if (CI->isMinValue(false)) // A >=u MIN -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
case ICmpInst::ICMP_SGE:
if (CI->isMinValue(true)) // A >=s MIN -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
}
switch (I.getPredicate()) {
default: break;
case ICmpInst::ICMP_ULT: // A <u MIN -> FALSE
@ -5298,64 +5321,11 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
if (isMaxValueMinusOne(CI, true)) // A >s MAX-1 -> A == MAX
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
break;
case ICmpInst::ICMP_ULE:
if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (CI->isMinValue(false)) // A <=u MIN -> A == MIN
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
if (isMaxValueMinusOne(CI,false)) // A <=u MAX-1 -> A != MAX
return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
break;
case ICmpInst::ICMP_SLE:
if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (CI->isMinValue(true)) // A <=s MIN -> A == MIN
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
if (isMaxValueMinusOne(CI,true)) // A <=s MAX-1 -> A != MAX
return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
break;
case ICmpInst::ICMP_UGE:
if (CI->isMinValue(false)) // A >=u MIN -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (CI->isMaxValue(false)) // A >=u MAX -> A == MAX
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
if (isMinValuePlusOne(CI,false)) // A >=u MIN-1 -> A != MIN
return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
break;
case ICmpInst::ICMP_SGE:
if (CI->isMinValue(true)) // A >=s MIN -> TRUE
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (CI->isMaxValue(true)) // A >=s MAX -> A == MAX
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
if (isMinValuePlusOne(CI,true)) // A >=s MIN-1 -> A != MIN
return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
break;
}
// If we still have a icmp le or icmp ge instruction, turn it into the
// appropriate icmp lt or icmp gt instruction. Since the border cases have
// already been handled above, this requires little checking.
//
switch (I.getPredicate()) {
default: break;
case ICmpInst::ICMP_ULE:
return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
case ICmpInst::ICMP_SLE:
return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
case ICmpInst::ICMP_UGE:
return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
case ICmpInst::ICMP_SGE:
return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
}
// See if we can fold the comparison based on bits known to be zero or one
// in the input. If this comparison is a normal comparison, it demands all
// bits, if it is a sign bit comparison, it only demands the sign bit.
bool UnusedBit;
bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
@ -5368,56 +5338,51 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
return &I;
// Given the known and unknown bits, compute a range that the LHS could be
// in.
if ((KnownOne | KnownZero) != 0) {
// Compute the Min, Max and RHS values based on the known bits. For the
// EQ and NE we use unsigned values.
APInt Min(BitWidth, 0), Max(BitWidth, 0);
const APInt& RHSVal = CI->getValue();
if (ICmpInst::isSignedPredicate(I.getPredicate())) {
ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
Max);
} else {
ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
Max);
}
switch (I.getPredicate()) { // LE/GE have been folded already.
default: assert(0 && "Unknown icmp opcode!");
case ICmpInst::ICMP_EQ:
if (Max.ult(RHSVal) || Min.ugt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
case ICmpInst::ICMP_NE:
if (Max.ult(RHSVal) || Min.ugt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
break;
case ICmpInst::ICMP_ULT:
if (Max.ult(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Min.uge(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
case ICmpInst::ICMP_UGT:
if (Min.ugt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Max.ule(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
case ICmpInst::ICMP_SLT:
if (Max.slt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Min.sgt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
if (Max == RHSVal) // A <s MAX -> A != MAX
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
break;
case ICmpInst::ICMP_SGT:
if (Min.sgt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Max.sle(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
}
// in. Compute the Min, Max and RHS values based on the known bits. For the
// EQ and NE we use unsigned values.
APInt Min(BitWidth, 0), Max(BitWidth, 0);
const APInt& RHSVal = CI->getValue();
if (ICmpInst::isSignedPredicate(I.getPredicate()))
ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min, Max);
else
ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,Min,Max);
switch (I.getPredicate()) { // LE/GE have been folded already.
default: assert(0 && "Unknown icmp opcode!");
case ICmpInst::ICMP_EQ:
if (Max.ult(RHSVal) || Min.ugt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
case ICmpInst::ICMP_NE:
if (Max.ult(RHSVal) || Min.ugt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
break;
case ICmpInst::ICMP_ULT:
if (Max.ult(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Min.uge(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
case ICmpInst::ICMP_UGT:
if (Min.ugt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Max.ule(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
case ICmpInst::ICMP_SLT:
if (Max.slt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Min.sgt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
if (Max == RHSVal) // A <s MAX -> A != MAX
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
break;
case ICmpInst::ICMP_SGT:
if (Min.sgt(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
if (Max.sle(RHSVal))
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
break;
}
// Since the RHS is a ConstantInt (CI), if the left hand side is an