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Switch GVN::processNonLocalLoad to using the new

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MemDep::getNonLocalPointerDependency method.  There are
some open issues with this (missed optimizations) and
plenty of future work, but this does allow GVN to eliminate
*slightly* more loads (49246 vs 49033).

Switching over now allows simplification of the other code
path in memdep.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60780 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-12-09 19:25:07 +00:00
parent ae1993114f
commit 91bcf6450a
1 changed files with 11 additions and 20 deletions
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31
lib/Transforms/Scalar/GVN.cpp
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@ -938,18 +938,17 @@ SpeculationFailure:
bool GVN::processNonLocalLoad(LoadInst *LI,
SmallVectorImpl<Instruction*> &toErase) {
// Find the non-local dependencies of the load.
const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
MD->getNonLocalDependency(LI);
//DEBUG(cerr << "INVESTIGATING NONLOCAL LOAD: " << deps.size() << *LI);
SmallVector<MemoryDependenceAnalysis::NonLocalDepEntry, 64> Deps;
MD->getNonLocalPointerDependency(LI->getOperand(0), true, LI->getParent(),
Deps);
//DEBUG(cerr << "INVESTIGATING NONLOCAL LOAD: " << Deps.size() << *LI);
// If we had to process more than one hundred blocks to find the
// dependencies, this load isn't worth worrying about. Optimizing
// it will be too expensive.
if (deps.size() > 100)
if (Deps.size() > 100)
return false;
BasicBlock *EntryBlock = &LI->getParent()->getParent()->getEntryBlock();
// Filter out useless results (non-locals, etc). Keep track of the blocks
// where we have a value available in repl, also keep track of whether we see
// dependencies that produce an unknown value for the load (such as a call
@ -957,18 +956,9 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
SmallVector<std::pair<BasicBlock*, Value*>, 16> ValuesPerBlock;
SmallVector<BasicBlock*, 16> UnavailableBlocks;
for (unsigned i = 0, e = deps.size(); i != e; ++i) {
BasicBlock *DepBB = deps[i].first;
MemDepResult DepInfo = deps[i].second;
if (DepInfo.isNonLocal()) {
// If this is a non-local dependency in the entry block, then we depend on
// the value live-in at the start of the function. We could insert a load
// in the entry block to get this, but for now we'll just bail out.
if (DepBB == EntryBlock)
UnavailableBlocks.push_back(DepBB);
continue;
}
for (unsigned i = 0, e = Deps.size(); i != e; ++i) {
BasicBlock *DepBB = Deps[i].first;
MemDepResult DepInfo = Deps[i].second;
if (DepInfo.isClobber()) {
UnavailableBlocks.push_back(DepBB);
@ -984,7 +974,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
continue;
}
if (StoreInst* S = dyn_cast<StoreInst>(DepInfo.getInst())) {
if (StoreInst* S = dyn_cast<StoreInst>(DepInst)) {
// Reject loads and stores that are to the same address but are of
// different types.
// NOTE: 403.gcc does have this case (e.g. in readonly_fields_p) because
@ -997,7 +987,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
ValuesPerBlock.push_back(std::make_pair(DepBB, S->getOperand(0)));
} else if (LoadInst* LD = dyn_cast<LoadInst>(DepInfo.getInst())) {
} else if (LoadInst* LD = dyn_cast<LoadInst>(DepInst)) {
if (LD->getType() != LI->getType()) {
UnavailableBlocks.push_back(DepBB);
continue;
@ -1019,6 +1009,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
if (UnavailableBlocks.empty()) {
// Use cached PHI construction information from previous runs
SmallPtrSet<Instruction*, 4> &p = phiMap[LI->getPointerOperand()];
// FIXME: What does phiMap do? Are we positive it isn't getting invalidated?
for (SmallPtrSet<Instruction*, 4>::iterator I = p.begin(), E = p.end();
I != E; ++I) {
if ((*I)->getParent() == LI->getParent()) {