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Factor out the new <= and >= analysis code into SimplifyICmpOperands.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102922 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-05-03 16:35:17 +00:00
parent 7c24ff12c4
commit 03557dc0ad
1 changed files with 62 additions and 51 deletions
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113
lib/Analysis/ScalarEvolution.cpp
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@ -3908,6 +3908,9 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
Cond = ICmpInst::getSwappedPredicate(Cond);
}
// Simplify the operands before analyzing them.
(void)SimplifyICmpOperands(Cond, LHS, RHS);
// If we have a comparison of a chrec against a constant, try to use value
// ranges to answer this query.
if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
@ -3921,57 +3924,6 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
}
// If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
// adding or subtracting 1 from one of the operands.
switch (Cond) {
case ICmpInst::ICMP_SLE:
if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Cond = ICmpInst::ICMP_SLT;
} else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Cond = ICmpInst::ICMP_SLT;
}
break;
case ICmpInst::ICMP_SGE:
if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Cond = ICmpInst::ICMP_SGT;
} else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Cond = ICmpInst::ICMP_SGT;
}
break;
case ICmpInst::ICMP_ULE:
if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Cond = ICmpInst::ICMP_ULT;
} else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Cond = ICmpInst::ICMP_ULT;
}
break;
case ICmpInst::ICMP_UGE:
if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Cond = ICmpInst::ICMP_UGT;
} else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Cond = ICmpInst::ICMP_UGT;
}
break;
default:
break;
}
switch (Cond) {
case ICmpInst::ICMP_NE: { // while (X != Y)
// Convert to: while (X-Y != 0)
@ -4987,6 +4939,65 @@ bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
goto trivially_false;
}
// If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
// adding or subtracting 1 from one of the operands.
switch (Pred) {
case ICmpInst::ICMP_SLE:
if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Pred = ICmpInst::ICMP_SLT;
Changed = true;
} else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), -1, true), LHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Pred = ICmpInst::ICMP_SLT;
Changed = true;
}
break;
case ICmpInst::ICMP_SGE:
if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), -1, true), RHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Pred = ICmpInst::ICMP_SGT;
Changed = true;
} else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
/*HasNUW=*/false, /*HasNSW=*/true);
Pred = ICmpInst::ICMP_SGT;
Changed = true;
}
break;
case ICmpInst::ICMP_ULE:
if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), 1, false), RHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Pred = ICmpInst::ICMP_ULT;
Changed = true;
} else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), -1, false), LHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Pred = ICmpInst::ICMP_ULT;
Changed = true;
}
break;
case ICmpInst::ICMP_UGE:
if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) {
RHS = getAddExpr(getConstant(RHS->getType(), -1, false), RHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Pred = ICmpInst::ICMP_UGT;
Changed = true;
} else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) {
LHS = getAddExpr(getConstant(RHS->getType(), 1, false), LHS,
/*HasNUW=*/true, /*HasNSW=*/false);
Pred = ICmpInst::ICMP_UGT;
Changed = true;
}
break;
default:
break;
}
// TODO: More simplifications are possible here.
return Changed;