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Fix LSR to keep the RegUseTracker up to date when combining users.

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This doesn't usually matter, because the other heuristics usually
succeed regardless, but it's good to keep the register use
bookkeeping consistent.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116005 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-10-07 23:33:43 +00:00
parent d82e9e7d93
commit c6897706b7
1 changed files with 19 additions and 8 deletions
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27
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -113,7 +113,7 @@ class RegUseTracker {
public:
void CountRegister(const SCEV *Reg, size_t LUIdx);
void DropRegister(const SCEV *Reg, size_t LUIdx);
void DropUse(size_t LUIdx);
void SwapAndDropUse(size_t LUIdx, size_t LastLUIdx);
bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const;
@ -152,11 +152,19 @@ RegUseTracker::DropRegister(const SCEV *Reg, size_t LUIdx) {
}
void
RegUseTracker::DropUse(size_t LUIdx) {
// Remove the use index from every register's use list.
RegUseTracker::SwapAndDropUse(size_t LUIdx, size_t LastLUIdx) {
assert(LUIdx <= LastLUIdx);
// Update RegUses. The data structure is not optimized for this purpose;
// we must iterate through it and update each of the bit vectors.
for (RegUsesTy::iterator I = RegUsesMap.begin(), E = RegUsesMap.end();
I != E; ++I)
I->second.UsedByIndices.reset(LUIdx);
I != E; ++I) {
SmallBitVector &UsedByIndices = I->second.UsedByIndices;
if (LUIdx < UsedByIndices.size())
UsedByIndices[LUIdx] =
LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : 0;
UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx));
}
}
bool
@ -1339,7 +1347,7 @@ class LSRInstance {
LSRUse::KindType Kind,
const Type *AccessTy);
void DeleteUse(LSRUse &LU);
void DeleteUse(LSRUse &LU, size_t LUIdx);
LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU);
@ -1923,10 +1931,13 @@ LSRInstance::getUse(const SCEV *&Expr,
}
/// DeleteUse - Delete the given use from the Uses list.
void LSRInstance::DeleteUse(LSRUse &LU) {
void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) {
if (&LU != &Uses.back())
std::swap(LU, Uses.back());
Uses.pop_back();
// Update RegUses.
RegUses.SwapAndDropUse(LUIdx, Uses.size());
}
/// FindUseWithFormula - Look for a use distinct from OrigLU which is has
@ -3032,7 +3043,7 @@ void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {
}
// Delete the old use.
DeleteUse(LU);
DeleteUse(LU, LUIdx);
--LUIdx;
--NumUses;
break;