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Reapply [MergeLoadStoreMotion] Don't require GEP for sinking

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Reapply with a fix for a failing debuginfo assignment tracking test.

-----

Allow sinking stores where both operands are the same, don't require
them to have an identical GEP in each block.

This came up when migrating tests to opaque pointers, where
zero-index GEPs are omitted.
This commit is contained in:
Nikita Popov 2022-12-27 12:17:58 +01:00
parent 81fa9ac9ed
commit cb03470aef
3 changed files with 30 additions and 26 deletions
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44
llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp
View File

@ -220,27 +220,29 @@ PHINode *MergedLoadStoreMotion::getPHIOperand(BasicBlock *BB, StoreInst *S0,
}
///
/// Check if 2 stores can be sunk together with corresponding GEPs
/// Check if 2 stores can be sunk, optionally together with corresponding GEPs.
///
bool MergedLoadStoreMotion::canSinkStoresAndGEPs(StoreInst *S0,
StoreInst *S1) const {
auto *A0 = dyn_cast<Instruction>(S0->getPointerOperand());
auto *A1 = dyn_cast<Instruction>(S1->getPointerOperand());
return A0 && A1 && A0->isIdenticalTo(A1) && A0->hasOneUse() &&
(A0->getParent() == S0->getParent()) && A1->hasOneUse() &&
(A1->getParent() == S1->getParent()) && isa<GetElementPtrInst>(A0);
if (S0->getPointerOperand() == S1->getPointerOperand())
return true;
auto *GEP0 = dyn_cast<GetElementPtrInst>(S0->getPointerOperand());
auto *GEP1 = dyn_cast<GetElementPtrInst>(S1->getPointerOperand());
return GEP0 && GEP1 && GEP0->isIdenticalTo(GEP1) && GEP0->hasOneUse() &&
(GEP0->getParent() == S0->getParent()) && GEP1->hasOneUse() &&
(GEP1->getParent() == S1->getParent());
}
///
/// Merge two stores to same address and sink into \p BB
///
/// Also sinks GEP instruction computing the store address
/// Optionally also sinks GEP instruction computing the store address
///
void MergedLoadStoreMotion::sinkStoresAndGEPs(BasicBlock *BB, StoreInst *S0,
StoreInst *S1) {
Value *Ptr0 = S0->getPointerOperand();
Value *Ptr1 = S1->getPointerOperand();
// Only one definition?
auto *A0 = dyn_cast<Instruction>(S0->getPointerOperand());
auto *A1 = dyn_cast<Instruction>(S1->getPointerOperand());
LLVM_DEBUG(dbgs() << "Sink Instruction into BB \n"; BB->dump();
dbgs() << "Instruction Left\n"; S0->dump(); dbgs() << "\n";
dbgs() << "Instruction Right\n"; S1->dump(); dbgs() << "\n");
@ -254,23 +256,25 @@ void MergedLoadStoreMotion::sinkStoresAndGEPs(BasicBlock *BB, StoreInst *S0,
// Create the new store to be inserted at the join point.
StoreInst *SNew = cast<StoreInst>(S0->clone());
Instruction *ANew = A0->clone();
SNew->insertBefore(&*InsertPt);
ANew->insertBefore(SNew);
ANew->applyMergedLocation(A0->getDebugLoc(), A1->getDebugLoc());
assert(S0->getParent() == A0->getParent());
assert(S1->getParent() == A1->getParent());
// New PHI operand? Use it.
if (PHINode *NewPN = getPHIOperand(BB, S0, S1))
SNew->setOperand(0, NewPN);
S0->eraseFromParent();
S1->eraseFromParent();
A0->replaceAllUsesWith(ANew);
A0->eraseFromParent();
A1->replaceAllUsesWith(ANew);
A1->eraseFromParent();
if (Ptr0 != Ptr1) {
auto *GEP0 = cast<GetElementPtrInst>(Ptr0);
auto *GEP1 = cast<GetElementPtrInst>(Ptr1);
Instruction *GEPNew = GEP0->clone();
GEPNew->insertBefore(SNew);
GEPNew->applyMergedLocation(GEP0->getDebugLoc(), GEP1->getDebugLoc());
SNew->setOperand(1, GEPNew);
GEP0->replaceAllUsesWith(GEPNew);
GEP0->eraseFromParent();
GEP1->replaceAllUsesWith(GEPNew);
GEP1->eraseFromParent();
}
}
///

8
llvm/test/Transforms/MergedLoadStoreMotion/st_sink_no_gep.ll
View File

@ -7,12 +7,12 @@ define void @no_gep_same_ptr(i1 %c, ptr %p, i32 %x, i32 %y) {
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 [[C:%.*]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: store i32 [[X:%.*]], ptr [[P:%.*]], align 4
; CHECK-NEXT: br label [[IF_END:%.*]]
; CHECK: if.else:
; CHECK-NEXT: store i32 [[Y:%.*]], ptr [[P]], align 4
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[Y_SINK:%.*]] = phi i32 [ [[X:%.*]], [[IF_THEN]] ], [ [[Y:%.*]], [[IF_ELSE]] ]
; CHECK-NEXT: store i32 [[Y_SINK]], ptr [[P:%.*]], align 4
; CHECK-NEXT: ret void
;
entry:
@ -64,12 +64,12 @@ define void @shared_gep(i1 %c, ptr %p, i32 %x, i32 %y) {
; CHECK-NEXT: [[GEP:%.*]] = getelementptr i32, ptr [[P:%.*]], i32 1
; CHECK-NEXT: br i1 [[C:%.*]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: store i32 [[X:%.*]], ptr [[GEP]], align 4
; CHECK-NEXT: br label [[IF_END:%.*]]
; CHECK: if.else:
; CHECK-NEXT: store i32 [[Y:%.*]], ptr [[GEP]], align 4
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[Y_SINK:%.*]] = phi i32 [ [[X:%.*]], [[IF_THEN]] ], [ [[Y:%.*]], [[IF_ELSE]] ]
; CHECK-NEXT: store i32 [[Y_SINK]], ptr [[GEP]], align 4
; CHECK-NEXT: ret void
;
entry:

4
llvm/test/Transforms/MergedLoadStoreMotion/st_sink_split_bb.ll
View File

@ -48,12 +48,12 @@ define dso_local void @st_sink_split_bb(ptr nocapture %arg, ptr nocapture %arg1,
; CHECK-YES: bb5:
; CHECK-YES-NEXT: br i1 [[ARG3:%.*]], label [[BB6:%.*]], label [[BB7:%.*]]
; CHECK-YES: bb6:
; CHECK-YES-NEXT: store i32 2, ptr [[ARG]], align 4
; CHECK-YES-NEXT: br label [[BB9_SINK_SPLIT:%.*]]
; CHECK-YES: bb7:
; CHECK-YES-NEXT: store i32 3, ptr [[ARG]], align 4
; CHECK-YES-NEXT: br label [[BB9_SINK_SPLIT]]
; CHECK-YES: bb9.sink.split:
; CHECK-YES-NEXT: [[DOTSINK:%.*]] = phi i32 [ 2, [[BB6]] ], [ 3, [[BB7]] ]
; CHECK-YES-NEXT: store i32 [[DOTSINK]], ptr [[ARG]], align 4
; CHECK-YES-NEXT: [[TMP0:%.*]] = getelementptr inbounds i32, ptr [[ARG1:%.*]], i64 1
; CHECK-YES-NEXT: store i32 3, ptr [[TMP0]], align 4
; CHECK-YES-NEXT: [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[ARG1]], i64 2