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-rw-r--r--include/llvm/Analysis/MemoryDependenceAnalysis.h17
-rw-r--r--lib/Analysis/MemoryDependenceAnalysis.cpp205
-rw-r--r--test/Transforms/GVN/rle-must-alias.ll5
-rw-r--r--test/Transforms/GVN/rle-no-phi-translate.ll3
-rw-r--r--test/Transforms/GVN/rle-phi-translate.ll32
5 files changed, 218 insertions, 44 deletions
diff --git a/include/llvm/Analysis/MemoryDependenceAnalysis.h b/include/llvm/Analysis/MemoryDependenceAnalysis.h
index 8a5b07e..ac92b90 100644
--- a/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -156,12 +156,18 @@ namespace llvm {
/// ValueIsLoadPair - This is a pair<Value*, bool> where the bool is true if
/// the dependence is a read only dependence, false if read/write.
typedef PointerIntPair<Value*, 1, bool> ValueIsLoadPair;
-
+
+ /// BBSkipFirstBlockPair - This pair is used when caching information for a
+ /// block. If the pointer is null, the cache value is not a full query that
+ /// starts at the specified block. If non-null, the bool indicates whether
+ /// or not the contents of the block was skipped.
+ typedef PointerIntPair<BasicBlock*, 1, bool> BBSkipFirstBlockPair;
+
/// CachedNonLocalPointerInfo - This map stores the cached results of doing
/// a pointer lookup at the bottom of a block. The key of this map is the
/// pointer+isload bit, the value is a list of <bb->result> mappings.
- typedef DenseMap<ValueIsLoadPair,
- std::pair<BasicBlock*, NonLocalDepInfo> > CachedNonLocalPointerInfo;
+ typedef DenseMap<ValueIsLoadPair, std::pair<BBSkipFirstBlockPair,
+ NonLocalDepInfo> > CachedNonLocalPointerInfo;
CachedNonLocalPointerInfo NonLocalPointerDeps;
// A map from instructions to their non-local pointer dependencies.
@@ -259,10 +265,11 @@ namespace llvm {
MemDepResult getCallSiteDependencyFrom(CallSite C, bool isReadOnlyCall,
BasicBlock::iterator ScanIt,
BasicBlock *BB);
- void getNonLocalPointerDepFromBB(Value *Pointer, uint64_t Size,
+ bool getNonLocalPointerDepFromBB(Value *Pointer, uint64_t Size,
bool isLoad, BasicBlock *BB,
SmallVectorImpl<NonLocalDepEntry> &Result,
- SmallPtrSet<BasicBlock*, 64> &Visited);
+ DenseMap<BasicBlock*, Value*> &Visited,
+ bool SkipFirstBlock = false);
MemDepResult GetNonLocalInfoForBlock(Value *Pointer, uint64_t PointeeSize,
bool isLoad, BasicBlock *BB,
NonLocalDepInfo *Cache,
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index a9c9c17..1dfa1fa 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -382,8 +382,7 @@ MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
// isReadonlyCall - If this is a read-only call, we can be more aggressive.
bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
-
- // Visited checked first, vector in sorted order.
+
SmallPtrSet<BasicBlock*, 64> Visited;
unsigned NumSortedEntries = Cache.size();
@@ -487,10 +486,16 @@ getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB,
const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
- // While we have blocks to analyze, get their values.
- SmallPtrSet<BasicBlock*, 64> Visited;
- getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB,
- Result, Visited);
+ // This is the set of blocks we've inspected, and the pointer we consider in
+ // each block. Because of critical edges, we currently bail out if querying
+ // a block with multiple different pointers. This can happen during PHI
+ // translation.
+ DenseMap<BasicBlock*, Value*> Visited;
+ if (!getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB,
+ Result, Visited, true))
+ return;
+ Result.push_back(std::make_pair(FromBB,
+ MemDepResult::getClobber(FromBB->begin())));
}
/// GetNonLocalInfoForBlock - Compute the memdep value for BB with
@@ -566,35 +571,51 @@ GetNonLocalInfoForBlock(Value *Pointer, uint64_t PointeeSize,
}
-/// getNonLocalPointerDepFromBB -
-void MemoryDependenceAnalysis::
+/// getNonLocalPointerDepFromBB - Perform a dependency query based on
+/// pointer/pointeesize starting at the end of StartBB. Add any clobber/def
+/// results to the results vector and keep track of which blocks are visited in
+/// 'Visited'.
+///
+/// This has special behavior for the first block queries (when SkipFirstBlock
+/// is true). In this special case, it ignores the contents of the specified
+/// block and starts returning dependence info for its predecessors.
+///
+/// This function returns false on success, or true to indicate that it could
+/// not compute dependence information for some reason. This should be treated
+/// as a clobber dependence on the first instruction in the predecessor block.
+bool MemoryDependenceAnalysis::
getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
bool isLoad, BasicBlock *StartBB,
SmallVectorImpl<NonLocalDepEntry> &Result,
- SmallPtrSet<BasicBlock*, 64> &Visited) {
+ DenseMap<BasicBlock*, Value*> &Visited,
+ bool SkipFirstBlock) {
+
// Look up the cached info for Pointer.
ValueIsLoadPair CacheKey(Pointer, isLoad);
- std::pair<BasicBlock*, NonLocalDepInfo> &CacheInfo =
- NonLocalPointerDeps[CacheKey];
- NonLocalDepInfo *Cache = &CacheInfo.second;
+ std::pair<BBSkipFirstBlockPair, NonLocalDepInfo> *CacheInfo =
+ &NonLocalPointerDeps[CacheKey];
+ NonLocalDepInfo *Cache = &CacheInfo->second;
// If we have valid cached information for exactly the block we are
// investigating, just return it with no recomputation.
- if (CacheInfo.first == StartBB) {
+ if (CacheInfo->first == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
I != E; ++I)
if (!I->second.isNonLocal())
Result.push_back(*I);
++NumCacheCompleteNonLocalPtr;
- return;
+ return false;
}
// Otherwise, either this is a new block, a block with an invalid cache
// pointer or one that we're about to invalidate by putting more info into it
// than its valid cache info. If empty, the result will be valid cache info,
// otherwise it isn't.
- CacheInfo.first = Cache->empty() ? StartBB : 0;
+ if (Cache->empty())
+ CacheInfo->first = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
+ else
+ CacheInfo->first = BBSkipFirstBlockPair();
SmallVector<BasicBlock*, 32> Worklist;
Worklist.push_back(StartBB);
@@ -606,23 +627,14 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
// revisit blocks after we insert info for them.
unsigned NumSortedEntries = Cache->size();
- // SkipFirstBlock - If this is the very first block that we're processing, we
- // don't want to scan or think about its body, because the client was supposed
- // to do a local dependence query. Instead, just start processing it by
- // adding its predecessors to the worklist and iterating.
- bool SkipFirstBlock = Visited.empty();
-
while (!Worklist.empty()) {
BasicBlock *BB = Worklist.pop_back_val();
// Skip the first block if we have it.
- if (SkipFirstBlock) {
- SkipFirstBlock = false;
- } else {
+ if (!SkipFirstBlock) {
// Analyze the dependency of *Pointer in FromBB. See if we already have
// been here.
- if (!Visited.insert(BB))
- continue;
+ assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
// Get the dependency info for Pointer in BB. If we have cached
// information, we will use it, otherwise we compute it.
@@ -636,11 +648,123 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
}
}
- // Otherwise, we have to process all the predecessors of this block to scan
- // them as well.
- for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
- // TODO: PHI TRANSLATE.
- Worklist.push_back(*PI);
+ // If 'Pointer' is an instruction defined in this block, then we need to do
+ // phi translation to change it into a value live in the predecessor block.
+ // If phi translation fails, then we can't continue dependence analysis.
+ Instruction *PtrInst = dyn_cast<Instruction>(Pointer);
+ bool NeedsPHITranslation = PtrInst && PtrInst->getParent() == BB;
+
+ // If no PHI translation is needed, just add all the predecessors of this
+ // block to scan them as well.
+ if (!NeedsPHITranslation) {
+ SkipFirstBlock = false;
+ for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+ // Verify that we haven't looked at this block yet.
+ std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
+ InsertRes = Visited.insert(std::make_pair(*PI, Pointer));
+ if (InsertRes.second) {
+ // First time we've looked at *PI.
+ Worklist.push_back(*PI);
+ continue;
+ }
+
+ // If we have seen this block before, but it was with a different
+ // pointer then we have a phi translation failure and we have to treat
+ // this as a clobber.
+ if (InsertRes.first->second != Pointer)
+ goto PredTranslationFailure;
+ }
+ continue;
+ }
+
+ // If we do need to do phi translation, then there are a bunch of different
+ // cases, because we have to find a Value* live in the predecessor block. We
+ // know that PtrInst is defined in this block at least.
+
+ // If this is directly a PHI node, just use the incoming values for each
+ // pred as the phi translated version.
+ if (PHINode *PtrPHI = dyn_cast<PHINode>(PtrInst)) {
+ for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI){
+ BasicBlock *Pred = *PI;
+ Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred);
+
+ // Check to see if we have already visited this pred block with another
+ // pointer. If so, we can't do this lookup. This failure can occur
+ // with PHI translation when a critical edge exists and the PHI node in
+ // the successor translates to a pointer value different than the
+ // pointer the block was first analyzed with.
+ std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
+ InsertRes = Visited.insert(std::make_pair(Pred, PredPtr));
+
+ if (!InsertRes.second) {
+ // If the predecessor was visited with PredPtr, then we already did
+ // the analysis and can ignore it.
+ if (InsertRes.first->second == PredPtr)
+ continue;
+
+ // Otherwise, the block was previously analyzed with a different
+ // pointer. We can't represent the result of this case, so we just
+ // treat this as a phi translation failure.
+ goto PredTranslationFailure;
+ }
+
+ // If we have a problem phi translating, fall through to the code below
+ // to handle the failure condition.
+ if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred,
+ Result, Visited))
+ goto PredTranslationFailure;
+ }
+
+ // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
+ CacheInfo = &NonLocalPointerDeps[CacheKey];
+ Cache = &CacheInfo->second;
+
+ // Since we did phi translation, the "Cache" set won't contain all of the
+ // results for the query. This is ok (we can still use it to accelerate
+ // specific block queries) but we can't do the fastpath "return all
+ // results from the set" Clear out the indicator for this.
+ CacheInfo->first = BBSkipFirstBlockPair();
+ SkipFirstBlock = false;
+ continue;
+ }
+
+ // TODO: BITCAST, GEP.
+
+ // cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
+ // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
+ // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
+ PredTranslationFailure:
+
+ // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
+ CacheInfo = &NonLocalPointerDeps[CacheKey];
+ Cache = &CacheInfo->second;
+
+ // Since we did phi translation, the "Cache" set won't contain all of the
+ // results for the query. This is ok (we can still use it to accelerate
+ // specific block queries) but we can't do the fastpath "return all
+ // results from the set" Clear out the indicator for this.
+ CacheInfo->first = BBSkipFirstBlockPair();
+
+ // If *nothing* works, mark the pointer as being clobbered by the first
+ // instruction in this block.
+ //
+ // If this is the magic first block, return this as a clobber of the whole
+ // incoming value. Since we can't phi translate to one of the predecessors,
+ // we have to bail out.
+ if (SkipFirstBlock)
+ return true;
+
+ for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) {
+ assert(I != Cache->rend() && "Didn't find current block??");
+ if (I->first != BB)
+ continue;
+
+ assert(I->second.isNonLocal() &&
+ "Should only be here with transparent block");
+ I->second = MemDepResult::getClobber(BB->begin());
+ ReverseNonLocalPtrDeps[BB->begin()].insert(CacheKey.getOpaqueValue());
+ Result.push_back(*I);
+ break;
}
}
@@ -658,19 +782,22 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
Cache->insert(Entry, Val);
// FALL THROUGH.
}
- case 1: {
+ case 1:
// One new entry, Just insert the new value at the appropriate position.
- NonLocalDepEntry Val = Cache->back();
- Cache->pop_back();
- NonLocalDepInfo::iterator Entry =
- std::upper_bound(Cache->begin(), Cache->end(), Val);
- Cache->insert(Entry, Val);
+ if (Cache->size() != 1) {
+ NonLocalDepEntry Val = Cache->back();
+ Cache->pop_back();
+ NonLocalDepInfo::iterator Entry =
+ std::upper_bound(Cache->begin(), Cache->end(), Val);
+ Cache->insert(Entry, Val);
+ }
break;
- }
default:
// Added many values, do a full scale sort.
std::sort(Cache->begin(), Cache->end());
}
+
+ return false;
}
/// RemoveCachedNonLocalPointerDependencies - If P exists in
@@ -851,7 +978,7 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].second;
// The cache is not valid for any specific block anymore.
- NonLocalPointerDeps[P].first = 0;
+ NonLocalPointerDeps[P].first = BBSkipFirstBlockPair();
// Update any entries for RemInst to use the instruction after it.
for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
diff --git a/test/Transforms/GVN/rle-must-alias.ll b/test/Transforms/GVN/rle-must-alias.ll
index e507556..7108916 100644
--- a/test/Transforms/GVN/rle-must-alias.ll
+++ b/test/Transforms/GVN/rle-must-alias.ll
@@ -1,4 +1,9 @@
; RUN: llvm-as < %s | opt -gvn | llvm-dis | grep {DEAD.rle = phi i32}
+; XFAIL: *
+
+; FIXME: GVN should eliminate the fully redundant %9 GEP which
+; allows DEAD to be removed. This is PR3198.
+
; The %7 and %4 loads combine to make %DEAD unneeded.
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin7"
diff --git a/test/Transforms/GVN/rle-no-phi-translate.ll b/test/Transforms/GVN/rle-no-phi-translate.ll
index b7f0dbc..9ffbe21 100644
--- a/test/Transforms/GVN/rle-no-phi-translate.ll
+++ b/test/Transforms/GVN/rle-no-phi-translate.ll
@@ -1,4 +1,7 @@
; RUN: llvm-as < %s | opt -gvn | llvm-dis | grep load
+; FIXME: This should be promotable, but memdep/gvn don't track values
+; path/edge sensitively enough.
+
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin7"
diff --git a/test/Transforms/GVN/rle-phi-translate.ll b/test/Transforms/GVN/rle-phi-translate.ll
new file mode 100644
index 0000000..0f9c58f
--- /dev/null
+++ b/test/Transforms/GVN/rle-phi-translate.ll
@@ -0,0 +1,32 @@
+; RUN: llvm-as < %s | opt -gvn | llvm-dis | grep {%cv.rle = phi i32}
+; RUN: llvm-as < %s | opt -gvn | llvm-dis | grep {%bv.rle = phi i32}
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin7"
+
+define i32 @g(i32* %b, i32* %c) nounwind {
+entry:
+ %g = alloca i32 ; <i32*> [#uses=4]
+ %t1 = icmp eq i32* %b, null ; <i1> [#uses=1]
+ br i1 %t1, label %bb, label %bb1
+
+bb: ; preds = %entry
+ %t2 = load i32* %c, align 4 ; <i32> [#uses=1]
+ %t3 = add i32 %t2, 1 ; <i32> [#uses=1]
+ store i32 %t3, i32* %g, align 4
+ br label %bb2
+
+bb1: ; preds = %entry
+ %t5 = load i32* %b, align 4 ; <i32> [#uses=1]
+ %t6 = add i32 %t5, 1 ; <i32> [#uses=1]
+ store i32 %t6, i32* %g, align 4
+ br label %bb2
+
+bb2: ; preds = %bb1, %bb
+ %c_addr.0 = phi i32* [ %g, %bb1 ], [ %c, %bb ] ; <i32*> [#uses=1]
+ %b_addr.0 = phi i32* [ %b, %bb1 ], [ %g, %bb ] ; <i32*> [#uses=1]
+ %cv = load i32* %c_addr.0, align 4 ; <i32> [#uses=1]
+ %bv = load i32* %b_addr.0, align 4 ; <i32> [#uses=1]
+ %ret = add i32 %cv, %bv ; <i32> [#uses=1]
+ ret i32 %ret
+}
+
generated by cgit v1.1 at 2024-09-22 06:17:02 +0000