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-rw-r--r--lib/Transforms/Scalar/SROA.cpp129
1 files changed, 63 insertions, 66 deletions
diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index 114411e3f0..48bf64d0ac 100644
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -1954,9 +1954,9 @@ class AllocaSliceRewriter : public InstVisitor<AllocaSliceRewriter, bool> {
Use *OldUse;
Instruction *OldPtr;
- // Output members carrying state about the result of visiting and rewriting
- // the slice of the alloca.
- bool IsUsedByRewrittenSpeculatableInstructions;
+ // Track post-rewrite users which are PHI nodes and Selects.
+ SmallPtrSetImpl<PHINode *> &PHIUsers;
+ SmallPtrSetImpl<SelectInst *> &SelectUsers;
// Utility IR builder, whose name prefix is setup for each visited use, and
// the insertion point is set to point to the user.
@@ -1966,8 +1966,9 @@ public:
AllocaSliceRewriter(const DataLayout &DL, AllocaSlices &S, SROA &Pass,
AllocaInst &OldAI, AllocaInst &NewAI,
uint64_t NewBeginOffset, uint64_t NewEndOffset,
- bool IsVectorPromotable = false,
- bool IsIntegerPromotable = false)
+ bool IsVectorPromotable, bool IsIntegerPromotable,
+ SmallPtrSetImpl<PHINode *> &PHIUsers,
+ SmallPtrSetImpl<SelectInst *> &SelectUsers)
: DL(DL), S(S), Pass(Pass), OldAI(OldAI), NewAI(NewAI),
NewAllocaBeginOffset(NewBeginOffset), NewAllocaEndOffset(NewEndOffset),
NewAllocaTy(NewAI.getAllocatedType()),
@@ -1980,7 +1981,7 @@ public:
DL.getTypeSizeInBits(NewAI.getAllocatedType()))
: 0),
BeginOffset(), EndOffset(), IsSplittable(), IsSplit(), OldUse(),
- OldPtr(), IsUsedByRewrittenSpeculatableInstructions(false),
+ OldPtr(), PHIUsers(PHIUsers), SelectUsers(SelectUsers),
IRB(NewAI.getContext(), ConstantFolder()) {
if (VecTy) {
assert((DL.getTypeSizeInBits(ElementTy) % 8) == 0 &&
@@ -2013,20 +2014,6 @@ public:
return CanSROA;
}
- /// \brief Query whether this slice is used by speculatable instructions after
- /// rewriting.
- ///
- /// These instructions (PHIs and Selects currently) require the alloca slice
- /// to run back through the rewriter. Thus, they are promotable, but not on
- /// this iteration. This is distinct from a slice which is unpromotable for
- /// some other reason, in which case we don't even want to perform the
- /// speculation. This can be querried at any time and reflects whether (at
- /// that point) a visit call has rewritten a speculatable instruction on the
- /// current slice.
- bool isUsedByRewrittenSpeculatableInstructions() const {
- return IsUsedByRewrittenSpeculatableInstructions;
- }
-
private:
// Make sure the other visit overloads are visible.
using Base::visit;
@@ -2658,16 +2645,11 @@ private:
DEBUG(dbgs() << " to: " << PN << "\n");
deleteIfTriviallyDead(OldPtr);
- // Check whether we can speculate this PHI node, and if so remember that
- // fact and queue it up for another iteration after the speculation
- // occurs.
- if (isSafePHIToSpeculate(PN, &DL)) {
- Pass.SpeculatablePHIs.insert(&PN);
- IsUsedByRewrittenSpeculatableInstructions = true;
- return true;
- }
-
- return false; // PHIs can't be promoted on their own.
+ // PHIs can't be promoted on their own, but often can be speculated. We
+ // check the speculation outside of the rewriter so that we see the
+ // fully-rewritten alloca.
+ PHIUsers.insert(&PN);
+ return true;
}
bool visitSelectInst(SelectInst &SI) {
@@ -2687,16 +2669,11 @@ private:
DEBUG(dbgs() << " to: " << SI << "\n");
deleteIfTriviallyDead(OldPtr);
- // Check whether we can speculate this select instruction, and if so
- // remember that fact and queue it up for another iteration after the
- // speculation occurs.
- if (isSafeSelectToSpeculate(SI, &DL)) {
- Pass.SpeculatableSelects.insert(&SI);
- IsUsedByRewrittenSpeculatableInstructions = true;
- return true;
- }
-
- return false; // Selects can't be promoted on their own.
+ // Selects can't be promoted on their own, but often can be speculated. We
+ // check the speculation outside of the rewriter so that we see the
+ // fully-rewritten alloca.
+ SelectUsers.insert(&SI);
+ return true;
}
};
@@ -3132,17 +3109,17 @@ bool SROA::rewritePartition(AllocaInst &AI, AllocaSlices &S,
<< "[" << BeginOffset << "," << EndOffset << ") to: " << *NewAI
<< "\n");
- // Track the high watermark on several worklists that are only relevant for
+ // Track the high watermark on the worklist as it is only relevant for
// promoted allocas. We will reset it to this point if the alloca is not in
// fact scheduled for promotion.
unsigned PPWOldSize = PostPromotionWorklist.size();
- unsigned SPOldSize = SpeculatablePHIs.size();
- unsigned SSOldSize = SpeculatableSelects.size();
unsigned NumUses = 0;
+ SmallPtrSet<PHINode *, 8> PHIUsers;
+ SmallPtrSet<SelectInst *, 8> SelectUsers;
AllocaSliceRewriter Rewriter(*DL, S, *this, AI, *NewAI, BeginOffset,
EndOffset, IsVectorPromotable,
- IsIntegerPromotable);
+ IsIntegerPromotable, PHIUsers, SelectUsers);
bool Promotable = true;
for (ArrayRef<AllocaSlices::iterator>::const_iterator SUI = SplitUses.begin(),
SUE = SplitUses.end();
@@ -3163,33 +3140,53 @@ bool SROA::rewritePartition(AllocaInst &AI, AllocaSlices &S,
MaxUsesPerAllocaPartition =
std::max<unsigned>(NumUses, MaxUsesPerAllocaPartition);
- if (Promotable && !Rewriter.isUsedByRewrittenSpeculatableInstructions()) {
- DEBUG(dbgs() << " and queuing for promotion\n");
- PromotableAllocas.push_back(NewAI);
- } else if (NewAI != &AI ||
- (Promotable &&
- Rewriter.isUsedByRewrittenSpeculatableInstructions())) {
+ // Now that we've processed all the slices in the new partition, check if any
+ // PHIs or Selects would block promotion.
+ for (SmallPtrSetImpl<PHINode *>::iterator I = PHIUsers.begin(),
+ E = PHIUsers.end();
+ I != E; ++I)
+ if (!isSafePHIToSpeculate(**I, DL)) {
+ Promotable = false;
+ PHIUsers.clear();
+ SelectUsers.clear();
+ }
+ for (SmallPtrSetImpl<SelectInst *>::iterator I = SelectUsers.begin(),
+ E = SelectUsers.end();
+ I != E; ++I)
+ if (!isSafeSelectToSpeculate(**I, DL)) {
+ Promotable = false;
+ PHIUsers.clear();
+ SelectUsers.clear();
+ }
+
+ if (Promotable) {
+ if (PHIUsers.empty() && SelectUsers.empty()) {
+ // Promote the alloca.
+ PromotableAllocas.push_back(NewAI);
+ } else {
+ // If we have either PHIs or Selects to speculate, add them to those
+ // worklists and re-queue the new alloca so that we promote in on the
+ // next iteration.
+ for (SmallPtrSetImpl<PHINode *>::iterator I = PHIUsers.begin(),
+ E = PHIUsers.end();
+ I != E; ++I)
+ SpeculatablePHIs.insert(*I);
+ for (SmallPtrSetImpl<SelectInst *>::iterator I = SelectUsers.begin(),
+ E = SelectUsers.end();
+ I != E; ++I)
+ SpeculatableSelects.insert(*I);
+ Worklist.insert(NewAI);
+ }
+ } else {
// If we can't promote the alloca, iterate on it to check for new
// refinements exposed by splitting the current alloca. Don't iterate on an
// alloca which didn't actually change and didn't get promoted.
- //
- // Alternatively, if we could promote the alloca but have speculatable
- // instructions then we will speculate them after finishing our processing
- // of the original alloca. Mark the new one for re-visiting in the next
- // iteration so the speculated operations can be rewritten.
- //
- // FIXME: We should actually track whether the rewriter changed anything.
- Worklist.insert(NewAI);
- }
-
- // Drop any post-promotion work items if promotion didn't happen.
- if (!Promotable) {
+ if (NewAI != &AI)
+ Worklist.insert(NewAI);
+
+ // Drop any post-promotion work items if promotion didn't happen.
while (PostPromotionWorklist.size() > PPWOldSize)
PostPromotionWorklist.pop_back();
- while (SpeculatablePHIs.size() > SPOldSize)
- SpeculatablePHIs.pop_back();
- while (SpeculatableSelects.size() > SSOldSize)
- SpeculatableSelects.pop_back();
}
return true;
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-13 22:28:51 +0000