replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Now that we're using ConstantRange to represent potential values, make use of that represenation to 

create constraints from comparisons other than eq/neq.

llvm-svn: 110742
This commit is contained in:
Owen Anderson 2010-08-10 23:20:01 +00:00
parent 19183acd1f
commit 5f1dd0967d
1 changed files with 35 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
llvm/lib/Analysis/LazyValueInfo.cpp
View File

@ -91,6 +91,11 @@ public:
Res.markNotConstant(C);
return Res;
}
static LVILatticeVal getRange(ConstantRange CR) {
LVILatticeVal Res;
Res.markConstantRange(CR);
return Res;
}
bool isUndefined() const { return Tag == undefined; }
bool isConstant() const { return Tag == constant; }
@ -507,13 +512,35 @@ LVILatticeVal LVIQuery::getEdgeValue(BasicBlock *BBFrom, BasicBlock *BBTo) {
// If the condition of the branch is an equality comparison, we may be
// able to infer the value.
if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
if (ICI->isEquality() && ICI->getOperand(0) == Val &&
isa<Constant>(ICI->getOperand(1))) {
// We know that V has the RHS constant if this is a true SETEQ or
// false SETNE.
if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ))
return LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
return LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
if (ICI->getOperand(0) == Val && isa<Constant>(ICI->getOperand(1))) {
if (ICI->isEquality()) {
// We know that V has the RHS constant if this is a true SETEQ or
// false SETNE.
if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ))
return LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
return LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
} else if (ConstantInt *CI =
dyn_cast<ConstantInt>(ICI->getOperand(1))) {
// Calculate the range of values that would satisfy the comparison.
ConstantRange CmpRange(CI->getValue(), CI->getValue()+1);
ConstantRange TrueValues =
ConstantRange::makeICmpRegion(ICI->getPredicate(), CmpRange);
// If we're interested in the false dest, invert the condition.
if (!isTrueDest) TrueValues = TrueValues.inverse();
// Figure out the possible values of the query BEFORE this branch.
LVILatticeVal InBlock = getBlockValue(BBFrom);
if (!InBlock.isConstantRange()) return InBlock;
// Find all potential values that satisfy both the input and output
// conditions.
ConstantRange PossibleValues =
TrueValues.intersectWith(InBlock.getConstantRange());
return LVILatticeVal::getRange(PossibleValues);
}
}
}
}
@ -730,7 +757,7 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
ConstantRange TrueValues = ConstantRange::makeICmpRegion(Pred, RHS);
if (CR.intersectWith(TrueValues).isEmptySet())
return False;
else if (CR.intersectWith(TrueValues) == CR)
else if (TrueValues.contains(CR))
return True;
return Unknown;