Add trivial support for the invariance intrinsics to memdep. This logic is
purely local for now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85378 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index a071205..edead09 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -171,13 +171,42 @@
/// location depends. If isLoad is true, this routine ignore may-aliases with
/// read-only operations.
MemDepResult MemoryDependenceAnalysis::
-getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
+getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
BasicBlock::iterator ScanIt, BasicBlock *BB) {
+ Value* invariantTag = 0;
+
// Walk backwards through the basic block, looking for dependencies.
while (ScanIt != BB->begin()) {
Instruction *Inst = --ScanIt;
+ // If we're in an invariant region, no dependencies can be found before
+ // we pass an invariant-begin marker.
+ if (invariantTag == Inst) {
+ invariantTag = 0;
+ continue;
+
+ // If we pass an invariant-end marker, then we've just entered an invariant
+ // region and can start ignoring dependencies.
+ } else if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst)) {
+ if (II->getIntrinsicID() == Intrinsic::invariant_end) {
+ uint64_t invariantSize = ~0ULL;
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(2)))
+ invariantSize = CI->getZExtValue();
+
+ AliasAnalysis::AliasResult R =
+ AA->alias(II->getOperand(3), invariantSize, MemPtr, MemSize);
+ if (R == AliasAnalysis::MustAlias) {
+ invariantTag = II->getOperand(1);
+ continue;
+ }
+ }
+ }
+
+ // If we're querying on a load and we're in an invariant region, we're done
+ // at this point. Nothing a load depends on can live in an invariant region.
+ if (isLoad && invariantTag) continue;
+
// Debug intrinsics don't cause dependences.
if (isa<DbgInfoIntrinsic>(Inst)) continue;
@@ -201,6 +230,11 @@
return MemDepResult::getDef(Inst);
}
+ // If we're querying on a store and we're in an invariant region, we're done
+ // at this point. The only things that stores depend on that could exist in
+ // an invariant region are loads, which we've already checked.
+ if (invariantTag) continue;
+
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
// If alias analysis can tell that this store is guaranteed to not modify
// the query pointer, ignore it. Use getModRefInfo to handle cases where