aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--include/llvm/Analysis/ValueTracking.h8
-rw-r--r--lib/Analysis/ValueTracking.cpp31
-rw-r--r--lib/Transforms/Scalar/DeadStoreElimination.cpp22
-rw-r--r--test/Transforms/DeadStoreElimination/simple.ll10
4 files changed, 68 insertions, 3 deletions
diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index f2f9db4..e8d45f6 100644
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -151,6 +151,14 @@ namespace llvm {
return GetUnderlyingObject(const_cast<Value *>(V), TD, MaxLookup);
}
+ /// GetUnderlyingObjects - This method is similar to GetUnderlyingObject
+ /// except that it can look through phi and select instructions and return
+ /// multiple objects.
+ void GetUnderlyingObjects(Value *V,
+ SmallVectorImpl<Value *> &Objects,
+ const TargetData *TD = 0,
+ unsigned MaxLookup = 6);
+
/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer
/// are lifetime markers.
bool onlyUsedByLifetimeMarkers(const Value *V);
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 1418e01..d245783 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1796,6 +1796,37 @@ llvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) {
return V;
}
+void
+llvm::GetUnderlyingObjects(Value *V,
+ SmallVectorImpl<Value *> &Objects,
+ const TargetData *TD,
+ unsigned MaxLookup) {
+ SmallPtrSet<Value *, 4> Visited;
+ SmallVector<Value *, 4> Worklist;
+ Worklist.push_back(V);
+ do {
+ Value *P = Worklist.pop_back_val();
+ P = GetUnderlyingObject(P, TD, MaxLookup);
+
+ if (!Visited.insert(P))
+ continue;
+
+ if (SelectInst *SI = dyn_cast<SelectInst>(P)) {
+ Worklist.push_back(SI->getTrueValue());
+ Worklist.push_back(SI->getFalseValue());
+ continue;
+ }
+
+ if (PHINode *PN = dyn_cast<PHINode>(P)) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ Worklist.push_back(PN->getIncomingValue(i));
+ continue;
+ }
+
+ Objects.push_back(P);
+ } while (!Worklist.empty());
+}
+
/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer
/// are lifetime markers.
///
diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index a46e802..f498cc7 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -731,14 +731,30 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
// If we find a store, check to see if it points into a dead stack value.
if (hasMemoryWrite(BBI) && isRemovable(BBI)) {
// See through pointer-to-pointer bitcasts
- Value *Pointer = GetUnderlyingObject(getStoredPointerOperand(BBI));
+ SmallVector<Value *, 4> Pointers;
+ GetUnderlyingObjects(getStoredPointerOperand(BBI), Pointers);
// Stores to stack values are valid candidates for removal.
- if (DeadStackObjects.count(Pointer)) {
+ bool AllDead = true;
+ for (SmallVectorImpl<Value *>::iterator I = Pointers.begin(),
+ E = Pointers.end(); I != E; ++I)
+ if (!DeadStackObjects.count(*I)) {
+ AllDead = false;
+ break;
+ }
+
+ if (AllDead) {
Instruction *Dead = BBI++;
DEBUG(dbgs() << "DSE: Dead Store at End of Block:\n DEAD: "
- << *Dead << "\n Object: " << *Pointer << '\n');
+ << *Dead << "\n Objects: ";
+ for (SmallVectorImpl<Value *>::iterator I = Pointers.begin(),
+ E = Pointers.end(); I != E; ++I) {
+ dbgs() << **I;
+ if (llvm::next(I) != E)
+ dbgs() << ", ";
+ }
+ dbgs() << '\n');
// DCE instructions only used to calculate that store.
DeleteDeadInstruction(Dead, *MD, &DeadStackObjects);
diff --git a/test/Transforms/DeadStoreElimination/simple.ll b/test/Transforms/DeadStoreElimination/simple.ll
index 7c8a9b3..a386206 100644
--- a/test/Transforms/DeadStoreElimination/simple.ll
+++ b/test/Transforms/DeadStoreElimination/simple.ll
@@ -266,3 +266,13 @@ define void @test21() {
; CHECK-NEXT: ret void
ret void
}
+
+; CHECK: @test22(
+define void @test22(i1 %i, i32 %k, i32 %m) nounwind {
+ %k.addr = alloca i32
+ %m.addr = alloca i32
+ %k.addr.m.addr = select i1 %i, i32* %k.addr, i32* %m.addr
+ store i32 0, i32* %k.addr.m.addr, align 4
+; CHECK-NEXT: ret void
+ ret void
+}