[llvm-commits] [llvm] r60253 - in /llvm/trunk: include/llvm/Analysis/MemoryDependenceAnalysis.h lib/Analysis/MemoryDependenceAnalysis.cpp lib/Transforms/Scalar/GVN.cpp
Chris Lattner
sabre at nondot.org
Sat Nov 29 13:22:42 PST 2008
Author: lattner
Date: Sat Nov 29 15:22:42 2008
New Revision: 60253
URL: http://llvm.org/viewvc/llvm-project?rev=60253&view=rev
Log:
reimplement getNonLocalDependency with a simpler worklist
formulation that is faster and doesn't require nonLazyHelper.
Much less code.
Modified:
llvm/trunk/include/llvm/Analysis/MemoryDependenceAnalysis.h
llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
llvm/trunk/lib/Transforms/Scalar/GVN.cpp
Modified: llvm/trunk/include/llvm/Analysis/MemoryDependenceAnalysis.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/MemoryDependenceAnalysis.h?rev=60253&r1=60252&r2=60253&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/MemoryDependenceAnalysis.h (original)
+++ llvm/trunk/include/llvm/Analysis/MemoryDependenceAnalysis.h Sat Nov 29 15:22:42 2008
@@ -57,16 +57,16 @@
/// 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 @@
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 @@
MemDepResult getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
BasicBlock *BB);
- void nonLocalHelper(Instruction *Query, BasicBlock *BB,
- DenseMap<BasicBlock*, DepResultTy> &Result);
};
} // End llvm namespace
Modified: llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp?rev=60253&r1=60252&r2=60253&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp Sat Nov 29 15:22:42 2008
@@ -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 @@
} 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 @@
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 - 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)
+/// 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];
+
+ /// 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);
+ 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++;
+ }
+
+ // 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;
}
- return;
+ // 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);
}
- 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);
- }
+ // 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 @@
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;
Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=60253&r1=60252&r2=60253&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Sat Nov 29 15:22:42 2008
@@ -508,7 +508,7 @@
} 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 @@
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 @@
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.isNone()) {
+ repl[I->first] = UndefValue::get(L->getType());
+ continue;
+ }
- if (I->second.isNonLocal())
+ 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())
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