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ScalarEvolution: Construct SCEVDivision's Derived type instead of itself

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SCEVDivision::divide constructed an object of SCEVDivision<Derived>
instead of Derived.  divide would call visit which would cast the
SCEVDivision<Derived> to type Derived.  As it happens,
SCEVDivision<Derived> and Derived currently have the same layout but
this is fragile and grounds for UB.

Instead, just construct Derived.  No functional change intended.

llvm-svn: 222126
This commit is contained in:
David Majnemer 2014-11-17 11:27:45 +00:00
parent 93a823bc7a
commit b5ae33d9e3
1 changed files with 21 additions and 12 deletions
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33
lib/Analysis/ScalarEvolution.cpp
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@ -767,7 +767,7 @@ public:
const SCEV **Remainder) {
assert(Numerator && Denominator && "Uninitialized SCEV");
SCEVDivision<Derived> D(SE, Numerator, Denominator);
Derived D(SE, Numerator, Denominator);
// Check for the trivial case here to avoid having to check for it in the
// rest of the code.
@ -808,17 +808,6 @@ public:
*Remainder = D.Remainder;
}
SCEVDivision(ScalarEvolution &S, const SCEV *Numerator, const SCEV *Denominator)
: SE(S), Denominator(Denominator) {
Zero = SE.getConstant(Denominator->getType(), 0);
One = SE.getConstant(Denominator->getType(), 1);
// By default, we don't know how to divide Expr by Denominator.
// Providing the default here simplifies the rest of the code.
Quotient = Zero;
Remainder = Numerator;
}
// Except in the trivial case described above, we do not know how to divide
// Expr by Denominator for the following functions with empty implementation.
void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
@ -953,6 +942,18 @@ public:
}
private:
SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
const SCEV *Denominator)
: SE(S), Denominator(Denominator) {
Zero = SE.getConstant(Denominator->getType(), 0);
One = SE.getConstant(Denominator->getType(), 1);
// By default, we don't know how to divide Expr by Denominator.
// Providing the default here simplifies the rest of the code.
Quotient = Zero;
Remainder = Numerator;
}
ScalarEvolution &SE;
const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
@ -961,6 +962,10 @@ private:
};
struct SCEVSDivision : public SCEVDivision<SCEVSDivision> {
SCEVSDivision(ScalarEvolution &S, const SCEV *Numerator,
const SCEV *Denominator)
: SCEVDivision(S, Numerator, Denominator) {}
void visitConstant(const SCEVConstant *Numerator) {
if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
Quotient = SE.getConstant(sdiv(Numerator, D));
@ -971,6 +976,10 @@ struct SCEVSDivision : public SCEVDivision<SCEVSDivision> {
};
struct SCEVUDivision : public SCEVDivision<SCEVUDivision> {
SCEVUDivision(ScalarEvolution &S, const SCEV *Numerator,
const SCEV *Denominator)
: SCEVDivision(S, Numerator, Denominator) {}
void visitConstant(const SCEVConstant *Numerator) {
if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
Quotient = SE.getConstant(udiv(Numerator, D));