[llvm-commits] [llvm] r109424 - in /llvm/trunk: include/llvm/Analysis/LazyValueInfo.h lib/Analysis/LazyValueInfo.cpp lib/Transforms/Scalar/JumpThreading.cpp
Owen Anderson
resistor at mac.com
Mon Jul 26 11:48:03 PDT 2010
Author: resistor
Date: Mon Jul 26 13:48:03 2010
New Revision: 109424
URL: http://llvm.org/viewvc/llvm-project?rev=109424&view=rev
Log:
Add an initial implementation of LazyValueInfo updating for JumpThreading. Disabled for now.
Modified:
llvm/trunk/include/llvm/Analysis/LazyValueInfo.h
llvm/trunk/lib/Analysis/LazyValueInfo.cpp
llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
Modified: llvm/trunk/include/llvm/Analysis/LazyValueInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/LazyValueInfo.h?rev=109424&r1=109423&r2=109424&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/LazyValueInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/LazyValueInfo.h Mon Jul 26 13:48:03 2010
@@ -57,6 +57,10 @@
/// constant on the specified edge. Return null if not.
Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB);
+ /// threadEdge - Inform the analysis cache that we have threaded an edge from
+ /// PredBB to OldSucc to be from PredBB to NewSucc instead.
+ void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc);
+
// Implementation boilerplate.
Modified: llvm/trunk/lib/Analysis/LazyValueInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LazyValueInfo.cpp?rev=109424&r1=109423&r2=109424&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LazyValueInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/LazyValueInfo.cpp Mon Jul 26 13:48:03 2010
@@ -217,6 +217,11 @@
/// ValueCache - This is all of the cached information for all values,
/// mapped from Value* to key information.
DenseMap<Value*, ValueCacheEntryTy> ValueCache;
+
+ /// OverDefinedCache - This tracks, on a per-block basis, the set of
+ /// values that are over-defined at the end of that block. This is required
+ /// for cache updating.
+ DenseMap<BasicBlock*, std::set<Value*> > OverDefinedCache;
public:
/// getValueInBlock - This is the query interface to determine the lattice
@@ -226,6 +231,11 @@
/// getValueOnEdge - This is the query interface to determine the lattice
/// value for the specified Value* that is true on the specified edge.
LVILatticeVal getValueOnEdge(Value *V, BasicBlock *FromBB,BasicBlock *ToBB);
+
+ /// threadEdge - This is the update interface to inform the cache that an
+ /// edge from PredBB to OldSucc has been threaded to be from PredBB to
+ /// NewSucc.
+ void threadEdge(BasicBlock *PredBB,BasicBlock *OldSucc,BasicBlock *NewSucc);
};
} // end anonymous namespace
@@ -270,12 +280,17 @@
/// This is all of the cached information about this value.
ValueCacheEntryTy &Cache;
+ /// This tracks, for each block, what values are overdefined.
+ DenseMap<BasicBlock*, std::set<Value*> > &OverDefinedCache;
+
/// NewBlocks - This is a mapping of the new BasicBlocks which have been
/// added to cache but that are not in sorted order.
DenseMap<BasicBlock*, LVILatticeVal> NewBlockInfo;
public:
- LVIQuery(Value *V, ValueCacheEntryTy &VC) : Val(V), Cache(VC) {
+ LVIQuery(Value *V, ValueCacheEntryTy &VC,
+ DenseMap<BasicBlock*, std::set<Value*> > &ODC)
+ : Val(V), Cache(VC), OverDefinedCache(ODC) {
}
~LVIQuery() {
@@ -306,6 +321,11 @@
array_pod_sort(Cache.begin(), Cache.end(),
BlockCacheEntryComparator::Compare);
+ for (DenseMap<BasicBlock*, LVILatticeVal>::iterator
+ I = NewBlockInfo.begin(), E = NewBlockInfo.end(); I != E; ++I) {
+ if (I->second.isOverdefined())
+ OverDefinedCache[I->first].insert(Val);
+ }
}
LVILatticeVal getBlockValue(BasicBlock *BB);
@@ -474,7 +494,8 @@
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
- LVILatticeVal Result = LVIQuery(V, ValueCache[V]).getBlockValue(BB);
+ LVILatticeVal Result = LVIQuery(V, ValueCache[V],
+ OverDefinedCache).getBlockValue(BB);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
@@ -488,14 +509,75 @@
DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
+
LVILatticeVal Result =
- LVIQuery(V, ValueCache[V]).getEdgeValue(FromBB, ToBB);
+ LVIQuery(V, ValueCache[V],
+ OverDefinedCache).getEdgeValue(FromBB, ToBB);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
}
+void LazyValueInfoCache::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
+ BasicBlock *NewSucc) {
+ // When an edge in the graph has been threaded, values that we could not
+ // determine a value for before (i.e. were marked overdefined) may be possible
+ // to solve now. We do NOT try to proactively update these values. Instead,
+ // we clear their entries from the cache, and allow lazy updating to recompute
+ // them when needed.
+
+ // The updating process is fairly simple: we need to dropped cached info
+ // for all values that were marked overdefined in OldSucc, and for those same
+ // values in any successor of OldSucc (except NewSucc) in which they were
+ // also marked overdefined.
+ std::vector<BasicBlock*> worklist;
+ worklist.push_back(OldSucc);
+
+ std::set<Value*> ClearSet = OverDefinedCache[OldSucc];
+ LVILatticeVal OverDef;
+ OverDef.markOverdefined();
+
+ // Use a worklist to perform a depth-first search of OldSucc's successors.
+ // NOTE: We do not need a visited list since any blocks we have already
+ // visited will have had their overdefined markers cleared already, and we
+ // thus won't loop to their successors.
+ while (!worklist.empty()) {
+ BasicBlock *ToUpdate = worklist.back();
+ worklist.pop_back();
+
+ // Skip blocks only accessible through NewSucc.
+ if (ToUpdate == NewSucc) continue;
+
+ bool changed = false;
+ std::set<Value*> &CurrentSet = OverDefinedCache[ToUpdate];
+ for (std::set<Value*>::iterator I = ClearSet.begin(),E = ClearSet.end();
+ I != E; ++I) {
+ // If a value was marked overdefined in OldSucc, and is here too...
+ if (CurrentSet.count(*I)) {
+ // Remove it from the caches.
+ ValueCacheEntryTy &Entry = ValueCache[*I];
+ ValueCacheEntryTy::iterator CI =
+ std::lower_bound(Entry.begin(), Entry.end(),
+ std::make_pair(ToUpdate, OverDef),
+ BlockCacheEntryComparator());
+ assert(CI != Entry.end() && "Couldn't find entry to update?");
+ Entry.erase(CI);
+
+ CurrentSet.erase(*I);
+
+ // If we removed anything, then we potentially need to update
+ // blocks successors too.
+ changed = true;
+ }
+ }
+
+ if (!changed) continue;
+
+ worklist.insert(worklist.end(), succ_begin(ToUpdate), succ_end(ToUpdate));
+ }
+}
+
//===----------------------------------------------------------------------===//
// LazyValueInfo Impl
//===----------------------------------------------------------------------===//
@@ -579,4 +661,7 @@
return Unknown;
}
-
+void LazyValueInfo::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
+ BasicBlock* NewSucc) {
+ getCache(PImpl).threadEdge(PredBB, OldSucc, NewSucc);
+}
Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=109424&r1=109423&r2=109424&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Mon Jul 26 13:48:03 2010
@@ -1314,6 +1314,9 @@
<< ", across block:\n "
<< *BB << "\n");
+ if (LVI)
+ LVI->threadEdge(PredBB, BB, SuccBB);
+
// We are going to have to map operands from the original BB block to the new
// copy of the block 'NewBB'. If there are PHI nodes in BB, evaluate them to
// account for entry from PredBB.
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