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MemorySSA: Kill the WalkTargetCache now that we have getBlockDefs.

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llvm-svn: 299294
This commit is contained in:
Daniel Berlin 2017-04-01 08:59:45 +00:00
parent 6b1240150f
commit 73d62d4a2b
1 changed files with 6 additions and 39 deletions
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45
lib/Transforms/Utils/MemorySSA.cpp
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@ -519,7 +519,6 @@ class ClobberWalker {
// Phi optimization bookkeeping
SmallVector<DefPath, 32> Paths;
DenseSet<ConstMemoryAccessPair> VisitedPhis;
DenseMap<const BasicBlock *, MemoryAccess *> WalkTargetCache;
void setUseCache(bool Use) { UseCache = Use; }
bool shouldIgnoreCache() const {
@ -557,46 +556,17 @@ class ClobberWalker {
}
/// Find the nearest def or phi that `From` can legally be optimized to.
///
/// FIXME: Deduplicate this with MSSA::findDominatingDef. Ideally, MSSA should
/// keep track of this information for us, and allow us O(1) lookups of this
/// info.
MemoryAccess *getWalkTarget(const MemoryPhi *From) {
MemoryAccess *getWalkTarget(const MemoryPhi *From) const {
assert(From->getNumOperands() && "Phi with no operands?");
BasicBlock *BB = From->getBlock();
auto At = WalkTargetCache.find(BB);
if (At != WalkTargetCache.end())
return At->second;
SmallVector<const BasicBlock *, 8> ToCache;
ToCache.push_back(BB);
MemoryAccess *Result = MSSA.getLiveOnEntryDef();
DomTreeNode *Node = DT.getNode(BB);
while ((Node = Node->getIDom())) {
auto At = WalkTargetCache.find(BB);
if (At != WalkTargetCache.end()) {
Result = At->second;
break;
}
auto *Accesses = MSSA.getBlockAccesses(Node->getBlock());
if (Accesses) {
auto Iter = find_if(reverse(*Accesses), [](const MemoryAccess &MA) {
return !isa<MemoryUse>(MA);
});
if (Iter != Accesses->rend()) {
Result = const_cast<MemoryAccess *>(&*Iter);
break;
}
}
ToCache.push_back(Node->getBlock());
auto *Defs = MSSA.getBlockDefs(Node->getBlock());
if (Defs)
return const_cast<MemoryAccess *>(&*Defs->rbegin());
}
for (const BasicBlock *BB : ToCache)
WalkTargetCache.insert({BB, Result});
return Result;
}
@ -991,7 +961,7 @@ public:
WalkerCache &WC)
: MSSA(MSSA), AA(AA), DT(DT), WC(WC), UseCache(true) {}
void reset() { WalkTargetCache.clear(); }
void reset() {}
/// Finds the nearest clobber for the given query, optimizing phis if
/// possible.
@ -1104,10 +1074,7 @@ public:
/// answer a clobber query.
void setAutoResetWalker(bool AutoReset) { AutoResetWalker = AutoReset; }
/// Drop the walker's persistent data structures. At the moment, this means
/// "drop the walker's cache of BasicBlocks ->
/// earliest-MemoryAccess-we-can-optimize-to". This is necessary if we're
/// going to have DT updates, if we remove MemoryAccesses, etc.
/// Drop the walker's persistent data structures.
void resetClobberWalker() { Walker.reset(); }
void verify(const MemorySSA *MSSA) override {