improve memdep to eliminate bitcasts (and aliases, and noop geps)
early for the stated reasons: this allows it to find more
equivalences and depend less on code layout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82404 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 97b791c..d5db2ed 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -521,6 +521,13 @@
const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
uint64_t PointeeSize = AA->getTypeStoreSize(EltTy);
+ // If Pointer is a bitcast instruction, chomp through to the pointee since
+ // they are must alias. This increases the effectiveness of caching by
+ // finding more equivalences, avoids having to phi translate the bitcast, and
+ // avoids conflicts where we are looking for two "different" values in the
+ // same block when they are really just must aliases.
+ Pointer = Pointer->stripPointerCasts();
+
// 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
@@ -660,7 +667,6 @@
SmallVectorImpl<NonLocalDepEntry> &Result,
DenseMap<BasicBlock*, Value*> &Visited,
bool SkipFirstBlock) {
-
// Look up the cached info for Pointer.
ValueIsLoadPair CacheKey(Pointer, isLoad);
@@ -793,6 +799,13 @@
BasicBlock *Pred = *PI;
Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred);
+ // If Pointer is a bitcast instruction, chomp through to the pointee since
+ // they are must alias. This increases the effectiveness of caching by
+ // finding more equivalences, avoids having to phi translate the bitcast, and
+ // avoids conflicts where we are looking for two "different" values in the
+ // same block when they are really just must aliases.
+ PredPtr = PredPtr->stripPointerCasts();
+
// 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