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Merge fixes for a couple cases where the compiler generated different i386 code depending on the host. In the base system this showed up as very small differences in a couple object files in buildworld for i386 depending on the host architecture (i386 or amd64). PR: 276961
128 lines
5.9 KiB
Text
128 lines
5.9 KiB
Text
commit 55a2a91c5e1bb39dd625ba56597608883fbcb318
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Author: Dimitry Andric <dim@FreeBSD.org>
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Date: Thu Jul 25 13:13:45 2024 +0200
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Merge commit 28a2b85602a5 from llvm-project (by Kazu Hirata):
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[DeadStoreElimination] Use SmallSetVector (NFC) (#79410)
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The use of SmallSetVector saves 0.58% of heap allocations during the
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compilation of a large preprocessed file, namely X86ISelLowering.cpp,
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for the X86 target. During the experiment, the final size of ToCheck
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was 8 or less 88% of the time.
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Merge commit 9e95c4947d31 from llvm-project (by Nikita Popov):
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[DSE] Fix non-determinism due to address reuse (#84943)
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The malloc->calloc fold creates a new MemoryAccess, which may end of at
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the same address as a previously deleted access inside SkipStores.
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To the most part, this is not a problem, because SkipStores is normally
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only used together with MemDefs. Neither the old malloc access nor the
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new calloc access will be part of MemDefs, so there is no problem here.
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However, SkipStores is also used in one more place: In the main DSE
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loop, ToCheck entries are checked against it. Fix this by not using
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SkipStores here, and instead using a separate set to track deletions
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inside this loop. This way it is not affected by the calloc optimization
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that happens outside it.
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This is all pretty ugly, but I haven't found another good way to fix it.
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Suggestions welcome.
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No test case as I don't have a reliable DSE-only test-case for this.
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Fixes https://github.com/llvm/llvm-project/issues/84458.
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This fixes another possible difference in output when building i386
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object files with a native or cross build of clang. (Specifically, the
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file sbin/ipf/ipmon/ipmon.o.)
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PR: 276961
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Reported by: cperciva
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MFC after: 3 days
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diff --git llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
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index 380d65836553..f0f0f5f28025 100644
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--- llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
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+++ llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
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@@ -1697,7 +1697,9 @@ struct DSEState {
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/// Delete dead memory defs and recursively add their operands to ToRemove if
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/// they became dead.
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- void deleteDeadInstruction(Instruction *SI) {
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+ void
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+ deleteDeadInstruction(Instruction *SI,
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+ SmallPtrSetImpl<MemoryAccess *> *Deleted = nullptr) {
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MemorySSAUpdater Updater(&MSSA);
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SmallVector<Instruction *, 32> NowDeadInsts;
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NowDeadInsts.push_back(SI);
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@@ -1718,6 +1720,8 @@ struct DSEState {
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if (IsMemDef) {
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auto *MD = cast<MemoryDef>(MA);
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SkipStores.insert(MD);
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+ if (Deleted)
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+ Deleted->insert(MD);
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if (auto *SI = dyn_cast<StoreInst>(MD->getMemoryInst())) {
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if (SI->getValueOperand()->getType()->isPointerTy()) {
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const Value *UO = getUnderlyingObject(SI->getValueOperand());
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@@ -2111,7 +2115,12 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
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unsigned WalkerStepLimit = MemorySSAUpwardsStepLimit;
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unsigned PartialLimit = MemorySSAPartialStoreLimit;
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// Worklist of MemoryAccesses that may be killed by KillingDef.
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- SetVector<MemoryAccess *> ToCheck;
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+ SmallSetVector<MemoryAccess *, 8> ToCheck;
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+ // Track MemoryAccesses that have been deleted in the loop below, so we can
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+ // skip them. Don't use SkipStores for this, which may contain reused
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+ // MemoryAccess addresses.
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+ SmallPtrSet<MemoryAccess *, 8> Deleted;
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+ [[maybe_unused]] unsigned OrigNumSkipStores = State.SkipStores.size();
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ToCheck.insert(KillingDef->getDefiningAccess());
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bool Shortend = false;
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@@ -2119,7 +2128,7 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
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// Check if MemoryAccesses in the worklist are killed by KillingDef.
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for (unsigned I = 0; I < ToCheck.size(); I++) {
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MemoryAccess *Current = ToCheck[I];
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- if (State.SkipStores.count(Current))
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+ if (Deleted.contains(Current))
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continue;
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std::optional<MemoryAccess *> MaybeDeadAccess = State.getDomMemoryDef(
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@@ -2166,7 +2175,7 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
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continue;
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LLVM_DEBUG(dbgs() << "DSE: Remove Dead Store:\n DEAD: " << *DeadI
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<< "\n KILLER: " << *KillingI << '\n');
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- State.deleteDeadInstruction(DeadI);
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+ State.deleteDeadInstruction(DeadI, &Deleted);
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++NumFastStores;
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MadeChange = true;
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} else {
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@@ -2203,7 +2212,7 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
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Shortend = true;
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// Remove killing store and remove any outstanding overlap
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// intervals for the updated store.
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- State.deleteDeadInstruction(KillingSI);
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+ State.deleteDeadInstruction(KillingSI, &Deleted);
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auto I = State.IOLs.find(DeadSI->getParent());
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if (I != State.IOLs.end())
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I->second.erase(DeadSI);
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@@ -2215,13 +2224,16 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
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if (OR == OW_Complete) {
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LLVM_DEBUG(dbgs() << "DSE: Remove Dead Store:\n DEAD: " << *DeadI
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<< "\n KILLER: " << *KillingI << '\n');
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- State.deleteDeadInstruction(DeadI);
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+ State.deleteDeadInstruction(DeadI, &Deleted);
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++NumFastStores;
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MadeChange = true;
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}
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}
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}
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+ assert(State.SkipStores.size() - OrigNumSkipStores == Deleted.size() &&
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+ "SkipStores and Deleted out of sync?");
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+
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// Check if the store is a no-op.
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if (!Shortend && State.storeIsNoop(KillingDef, KillingUndObj)) {
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LLVM_DEBUG(dbgs() << "DSE: Remove No-Op Store:\n DEAD: " << *KillingI
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