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Fix a bug in GetConstantFactor for affine expressions, in which the existing

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code was wrong for things like 3+4*i.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32662 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-12-19 01:16:02 +00:00
parent 49e6a9bc94
commit 75de5ab9f5
1 changed files with 9 additions and 5 deletions
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14
lib/Analysis/ScalarEvolution.cpp
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@ -74,6 +74,7 @@
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Streams.h"
#include "llvm/ADT/Statistic.h"
#include <ostream>
@ -1372,11 +1373,14 @@ static uint64_t GetConstantFactor(SCEVHandle S) {
}
if (SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
// FIXME: Generalize.
if (A->getNumOperands() == 2)
return std::min(GetConstantFactor(A->getOperand(0)),
GetConstantFactor(A->getOperand(1)));
// ?
// For now, we just handle linear expressions.
if (A->getNumOperands() == 2) {
// We want the GCD between the start and the stride value.
uint64_t Start = GetConstantFactor(A->getOperand(0));
if (Start == 1) return 1;
uint64_t Stride = GetConstantFactor(A->getOperand(1));
return GreatestCommonDivisor64(Start, Stride);
}
}
// SCEVSDivExpr, SCEVUnknown.