forked from OSchip/llvm-project
reimplement getNonLocalDependency with a simpler worklist
formulation that is faster and doesn't require nonLazyHelper. Much less code. llvm-svn: 60253
This commit is contained in:
Chris Lattner
parent
c40039c736
commit
f280b0c729
|
|
@ -57,16 +57,16 @@ namespace llvm {
|
|||
|
||||
/// isNormal - Return true if this MemDepResult represents a query that is
|
||||
/// a normal instruction dependency.
|
||||
bool isNormal() const { return Value.getInt() == Normal; }
|
||||
bool isNormal() const { return Value.getInt() == Normal; }
|
||||
|
||||
/// isNonLocal - Return true if this MemDepResult represents an query that
|
||||
/// is transparent to the start of the block, but where a non-local hasn't
|
||||
/// been done.
|
||||
bool isNonLocal() const { return Value.getInt() == NonLocal; }
|
||||
bool isNonLocal() const { return Value.getInt() == NonLocal; }
|
||||
|
||||
/// isNone - Return true if this MemDepResult represents a query that
|
||||
/// doesn't depend on any instruction.
|
||||
bool isNone() const { return Value.getInt() == None; }
|
||||
bool isNone() const { return Value.getInt() == None; }
|
||||
|
||||
/// getInst() - If this is a normal dependency, return the instruction that
|
||||
/// is depended on. Otherwise, return null.
|
||||
|
|
@ -167,9 +167,13 @@ namespace llvm {
|
|||
BasicBlock::iterator ScanIt, BasicBlock *BB);
|
||||
|
||||
|
||||
/// getNonLocalDependency - Fills the passed-in map with the non-local
|
||||
/// dependencies of the queries. The map will contain NonLocal for
|
||||
/// blocks between the query and its dependencies.
|
||||
/// getNonLocalDependency - Perform a full dependency query for the
|
||||
/// specified instruction, returning the set of blocks that the value is
|
||||
/// potentially live across. The returned set of results will include a
|
||||
/// "NonLocal" result for all blocks where the value is live across.
|
||||
///
|
||||
/// This method assumes the instruction returns a "nonlocal" dependency
|
||||
/// within its own block.
|
||||
void getNonLocalDependency(Instruction *QueryInst,
|
||||
DenseMap<BasicBlock*, MemDepResult> &Result);
|
||||
|
||||
|
|
@ -207,8 +211,6 @@ namespace llvm {
|
|||
|
||||
MemDepResult getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
|
||||
BasicBlock *BB);
|
||||
void nonLocalHelper(Instruction *Query, BasicBlock *BB,
|
||||
DenseMap<BasicBlock*, DepResultTy> &Result);
|
||||
};
|
||||
|
||||
} // End llvm namespace
|
||||
|
|
|
|||
|
|
@ -28,13 +28,6 @@
|
|||
#include "llvm/Target/TargetData.h"
|
||||
using namespace llvm;
|
||||
|
||||
// Control the calculation of non-local dependencies by only examining the
|
||||
// predecessors if the basic block has less than X amount (50 by default).
|
||||
static cl::opt<int>
|
||||
PredLimit("nonlocaldep-threshold", cl::Hidden, cl::init(50),
|
||||
cl::desc("Control the calculation of non-local"
|
||||
"dependencies (default = 50)"));
|
||||
|
||||
STATISTIC(NumCacheNonlocal, "Number of cached non-local responses");
|
||||
STATISTIC(NumUncacheNonlocal, "Number of uncached non-local responses");
|
||||
|
||||
|
|
@ -105,8 +98,10 @@ getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
|
|||
} else if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
|
||||
Pointer = AI;
|
||||
if (ConstantInt *C = dyn_cast<ConstantInt>(AI->getArraySize()))
|
||||
// Use ABI size (size between elements), not store size (size of one
|
||||
// element without padding).
|
||||
PointerSize = C->getZExtValue() *
|
||||
TD.getTypeStoreSize(AI->getAllocatedType());
|
||||
TD.getABITypeSize(AI->getAllocatedType());
|
||||
else
|
||||
PointerSize = ~0UL;
|
||||
} else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
|
||||
|
|
@ -133,144 +128,84 @@ getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
|
|||
return MemDepResult::getNonLocal();
|
||||
}
|
||||
|
||||
/// nonLocalHelper - Private helper used to calculate non-local dependencies
|
||||
/// by doing DFS on the predecessors of a block to find its dependencies.
|
||||
void MemoryDependenceAnalysis::nonLocalHelper(Instruction* query,
|
||||
BasicBlock* block,
|
||||
DenseMap<BasicBlock*, DepResultTy> &resp) {
|
||||
// Set of blocks that we've already visited in our DFS
|
||||
SmallPtrSet<BasicBlock*, 4> visited;
|
||||
// If we're updating a dirtied cache entry, we don't need to reprocess
|
||||
// already computed entries.
|
||||
for (DenseMap<BasicBlock*, DepResultTy>::iterator I = resp.begin(),
|
||||
E = resp.end(); I != E; ++I)
|
||||
if (I->second.getInt() != Dirty)
|
||||
visited.insert(I->first);
|
||||
|
||||
// Current stack of the DFS
|
||||
SmallVector<BasicBlock*, 4> stack;
|
||||
for (pred_iterator PI = pred_begin(block), PE = pred_end(block);
|
||||
PI != PE; ++PI)
|
||||
stack.push_back(*PI);
|
||||
|
||||
// Do a basic DFS
|
||||
while (!stack.empty()) {
|
||||
BasicBlock* BB = stack.back();
|
||||
|
||||
// If we've already visited this block, no need to revist
|
||||
if (visited.count(BB)) {
|
||||
stack.pop_back();
|
||||
continue;
|
||||
}
|
||||
|
||||
// If we find a new block with a local dependency for query,
|
||||
// then we insert the new dependency and backtrack.
|
||||
if (BB != block) {
|
||||
visited.insert(BB);
|
||||
|
||||
MemDepResult localDep = getDependencyFrom(query, BB->end(), BB);
|
||||
if (!localDep.isNonLocal()) {
|
||||
resp.insert(std::make_pair(BB, ConvFromResult(localDep)));
|
||||
stack.pop_back();
|
||||
continue;
|
||||
}
|
||||
// If we re-encounter the starting block, we still need to search it
|
||||
// because there might be a dependency in the starting block AFTER
|
||||
// the position of the query. This is necessary to get loops right.
|
||||
} else if (BB == block) {
|
||||
visited.insert(BB);
|
||||
|
||||
MemDepResult localDep = getDependencyFrom(query, BB->end(), BB);
|
||||
if (localDep.getInst() != query)
|
||||
resp.insert(std::make_pair(BB, ConvFromResult(localDep)));
|
||||
|
||||
stack.pop_back();
|
||||
continue;
|
||||
}
|
||||
|
||||
// If we didn't find anything, recurse on the precessors of this block
|
||||
// Only do this for blocks with a small number of predecessors.
|
||||
bool predOnStack = false;
|
||||
bool inserted = false;
|
||||
if (std::distance(pred_begin(BB), pred_end(BB)) <= PredLimit) {
|
||||
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
|
||||
PI != PE; ++PI)
|
||||
if (!visited.count(*PI)) {
|
||||
stack.push_back(*PI);
|
||||
inserted = true;
|
||||
} else
|
||||
predOnStack = true;
|
||||
}
|
||||
|
||||
// If we inserted a new predecessor, then we'll come back to this block
|
||||
if (inserted)
|
||||
continue;
|
||||
// If we didn't insert because we have no predecessors, then this
|
||||
// query has no dependency at all.
|
||||
else if (!inserted && !predOnStack) {
|
||||
resp.insert(std::make_pair(BB, DepResultTy(0, None)));
|
||||
// If we didn't insert because our predecessors are already on the stack,
|
||||
// then we might still have a dependency, but it will be discovered during
|
||||
// backtracking.
|
||||
} else if (!inserted && predOnStack){
|
||||
resp.insert(std::make_pair(BB, DepResultTy(0, NonLocal)));
|
||||
}
|
||||
|
||||
stack.pop_back();
|
||||
}
|
||||
}
|
||||
/// getNonLocalDependency - Perform a full dependency query for the
|
||||
/// specified instruction, returning the set of blocks that the value is
|
||||
/// potentially live across. The returned set of results will include a
|
||||
/// "NonLocal" result for all blocks where the value is live across.
|
||||
///
|
||||
/// This method assumes the instruction returns a "nonlocal" dependency
|
||||
/// within its own block.
|
||||
///
|
||||
void MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst,
|
||||
DenseMap<BasicBlock*, MemDepResult> &Result) {
|
||||
assert(getDependency(QueryInst).isNonLocal() &&
|
||||
"getNonLocalDependency should only be used on insts with non-local deps!");
|
||||
DenseMap<BasicBlock*, DepResultTy> &Cache = NonLocalDeps[QueryInst];
|
||||
|
||||
/// getNonLocalDependency - Fills the passed-in map with the non-local
|
||||
/// dependencies of the queries. The map will contain NonLocal for
|
||||
/// blocks between the query and its dependencies.
|
||||
void MemoryDependenceAnalysis::getNonLocalDependency(Instruction* query,
|
||||
DenseMap<BasicBlock*, MemDepResult> &resp) {
|
||||
if (NonLocalDeps.count(query)) {
|
||||
DenseMap<BasicBlock*, DepResultTy> &cached = NonLocalDeps[query];
|
||||
NumCacheNonlocal++;
|
||||
|
||||
SmallVector<BasicBlock*, 4> dirtied;
|
||||
for (DenseMap<BasicBlock*, DepResultTy>::iterator I = cached.begin(),
|
||||
E = cached.end(); I != E; ++I)
|
||||
/// DirtyBlocks - This is the set of blocks that need to be recomputed. This
|
||||
/// can happen due to instructions being deleted etc.
|
||||
SmallVector<BasicBlock*, 32> DirtyBlocks;
|
||||
|
||||
if (!Cache.empty()) {
|
||||
// If we already have a partially computed set of results, scan them to
|
||||
// determine what is dirty, seeding our initial DirtyBlocks worklist.
|
||||
// FIXME: In the "don't need to be updated" case, this is expensive, why not
|
||||
// have a per-"cache" flag saying it is undirty?
|
||||
for (DenseMap<BasicBlock*, DepResultTy>::iterator I = Cache.begin(),
|
||||
E = Cache.end(); I != E; ++I)
|
||||
if (I->second.getInt() == Dirty)
|
||||
dirtied.push_back(I->first);
|
||||
DirtyBlocks.push_back(I->first);
|
||||
|
||||
for (SmallVector<BasicBlock*, 4>::iterator I = dirtied.begin(),
|
||||
E = dirtied.end(); I != E; ++I) {
|
||||
MemDepResult localDep = getDependencyFrom(query, (*I)->end(), *I);
|
||||
if (!localDep.isNonLocal())
|
||||
cached[*I] = ConvFromResult(localDep);
|
||||
else {
|
||||
cached.erase(*I);
|
||||
nonLocalHelper(query, *I, cached);
|
||||
}
|
||||
}
|
||||
|
||||
// Update the reverse non-local dependency cache.
|
||||
for (DenseMap<BasicBlock*, DepResultTy>::iterator I = cached.begin(),
|
||||
E = cached.end(); I != E; ++I) {
|
||||
if (Instruction *Inst = I->second.getPointer())
|
||||
ReverseNonLocalDeps[Inst].insert(query);
|
||||
resp[I->first] = ConvToResult(I->second);
|
||||
}
|
||||
|
||||
return;
|
||||
NumCacheNonlocal++;
|
||||
} else {
|
||||
// Seed DirtyBlocks with each of the preds of QueryInst's block.
|
||||
BasicBlock *QueryBB = QueryInst->getParent();
|
||||
// FIXME: use range insertion/append.
|
||||
for (pred_iterator PI = pred_begin(QueryBB), E = pred_end(QueryBB);
|
||||
PI != E; ++PI)
|
||||
DirtyBlocks.push_back(*PI);
|
||||
NumUncacheNonlocal++;
|
||||
}
|
||||
|
||||
NumUncacheNonlocal++;
|
||||
|
||||
// If not, go ahead and search for non-local deps.
|
||||
DenseMap<BasicBlock*, DepResultTy> &cached = NonLocalDeps[query];
|
||||
nonLocalHelper(query, query->getParent(), cached);
|
||||
|
||||
// Update the non-local dependency cache
|
||||
for (DenseMap<BasicBlock*, DepResultTy>::iterator I = cached.begin(),
|
||||
E = cached.end(); I != E; ++I) {
|
||||
// FIXME: Merge with the code above!
|
||||
if (Instruction *Inst = I->second.getPointer())
|
||||
ReverseNonLocalDeps[Inst].insert(query);
|
||||
resp[I->first] = ConvToResult(I->second);
|
||||
// Iterate while we still have blocks to update.
|
||||
while (!DirtyBlocks.empty()) {
|
||||
BasicBlock *DirtyBB = DirtyBlocks.back();
|
||||
DirtyBlocks.pop_back();
|
||||
|
||||
// Get the entry for this block. Note that this relies on DepResultTy
|
||||
// default initializing to Dirty.
|
||||
DepResultTy &DirtyBBEntry = Cache[DirtyBB];
|
||||
|
||||
// If DirtyBBEntry isn't dirty, it ended up on the worklist multiple times.
|
||||
if (DirtyBBEntry.getInt() != Dirty) continue;
|
||||
|
||||
// Find out if this block has a local dependency for QueryInst.
|
||||
// FIXME: If the dirty entry has an instruction pointer, scan from it!
|
||||
// FIXME: Don't convert back and forth for MemDepResult <-> DepResultTy.
|
||||
DirtyBBEntry = ConvFromResult(getDependencyFrom(QueryInst, DirtyBB->end(),
|
||||
DirtyBB));
|
||||
|
||||
// If the block has a dependency (i.e. it isn't completely transparent to
|
||||
// the value), remember it!
|
||||
if (DirtyBBEntry.getInt() != NonLocal) {
|
||||
// Keep the ReverseNonLocalDeps map up to date so we can efficiently
|
||||
// update this when we remove instructions.
|
||||
if (Instruction *Inst = DirtyBBEntry.getPointer())
|
||||
ReverseNonLocalDeps[Inst].insert(QueryInst);
|
||||
continue;
|
||||
}
|
||||
|
||||
// If the block *is* completely transparent to the load, we need to check
|
||||
// the predecessors of this block. Add them to our worklist.
|
||||
for (pred_iterator I = pred_begin(DirtyBB), E = pred_end(DirtyBB);
|
||||
I != E; ++I)
|
||||
DirtyBlocks.push_back(*I);
|
||||
}
|
||||
|
||||
// Copy the result into the output set.
|
||||
for (DenseMap<BasicBlock*, DepResultTy>::iterator I = Cache.begin(),
|
||||
E = Cache.end(); I != E; ++I)
|
||||
Result[I->first] = ConvToResult(I->second);
|
||||
}
|
||||
|
||||
/// getDependency - Return the instruction on which a memory operation
|
||||
|
|
@ -345,8 +280,10 @@ getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt,
|
|||
Value *Pointer = AI;
|
||||
uint64_t PointerSize;
|
||||
if (ConstantInt *C = dyn_cast<ConstantInt>(AI->getArraySize()))
|
||||
// Use ABI size (size between elements), not store size (size of one
|
||||
// element without padding).
|
||||
PointerSize = C->getZExtValue() *
|
||||
TD.getTypeStoreSize(AI->getAllocatedType());
|
||||
TD.getABITypeSize(AI->getAllocatedType());
|
||||
else
|
||||
PointerSize = ~0UL;
|
||||
|
||||
|
|
|
|||
|
|
@ -508,7 +508,7 @@ uint32_t ValueTable::lookup_or_add(Value* V) {
|
|||
} else if (Instruction *NonLocalDepInst = I->second.getInst()) {
|
||||
// FIXME: INDENT PROPERLY
|
||||
// FIXME: All duplicated with non-local case.
|
||||
if (DT->properlyDominates(I->first, C->getParent())) {
|
||||
if (cdep == 0 && DT->properlyDominates(I->first, C->getParent())) {
|
||||
if (CallInst* CD = dyn_cast<CallInst>(NonLocalDepInst))
|
||||
cdep = CD;
|
||||
else {
|
||||
|
|
@ -527,6 +527,12 @@ uint32_t ValueTable::lookup_or_add(Value* V) {
|
|||
return nextValueNumber++;
|
||||
}
|
||||
|
||||
// FIXME: THIS ISN'T SAFE: CONSIDER:
|
||||
// X = strlen(str)
|
||||
// if (C)
|
||||
// str[0] = 1;
|
||||
// Y = strlen(str)
|
||||
// This doesn't guarantee all-paths availability!
|
||||
if (cdep->getCalledFunction() != C->getCalledFunction() ||
|
||||
cdep->getNumOperands() != C->getNumOperands()) {
|
||||
valueNumbering.insert(std::make_pair(V, nextValueNumber));
|
||||
|
|
@ -874,16 +880,27 @@ bool GVN::processNonLocalLoad(LoadInst* L,
|
|||
if (deps.size() > 100)
|
||||
return false;
|
||||
|
||||
BasicBlock *EntryBlock = &L->getParent()->getParent()->getEntryBlock();
|
||||
|
||||
DenseMap<BasicBlock*, Value*> repl;
|
||||
|
||||
// Filter out useless results (non-locals, etc)
|
||||
for (DenseMap<BasicBlock*, MemDepResult>::iterator I = deps.begin(),
|
||||
E = deps.end(); I != E; ++I) {
|
||||
if (I->second.isNone())
|
||||
return false;
|
||||
|
||||
if (I->second.isNonLocal())
|
||||
if (I->second.isNone()) {
|
||||
repl[I->first] = UndefValue::get(L->getType());
|
||||
continue;
|
||||
}
|
||||
|
||||
if (I->second.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.
|
||||
// FIXME: Consider emitting a load in the entry block to catch this case!
|
||||
if (I->first == EntryBlock)
|
||||
return false;
|
||||
continue;
|
||||
}
|
||||
|
||||
if (StoreInst* S = dyn_cast<StoreInst>(I->second.getInst())) {
|
||||
if (S->getPointerOperand() != L->getPointerOperand())
|
||||
|
|
|
|||
Loading…
Reference in New Issue