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[PowerPC] support branch hint for AtomicExpandImpl::expandAtomicCmpXchg #152366

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[PowerPC] support branch hint for AtomicExpandImpl::expandAtomicCmpXchg #152366

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5afd456
add branch hint
diggerlin Jul 16, 2025
b6976bf
modify test case
diggerlin Jul 24, 2025
98d946a
change function name from getTrueBranchHintWeightForAtomicCmpXchgg to…
diggerlin Aug 7, 2025
5d2dcdd
using the target independ code
diggerlin Aug 7, 2025
70c1ccf
change test case
diggerlin Aug 8, 2025
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10 changes: 7 additions & 3 deletions llvm/lib/CodeGen/AtomicExpandPass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1454,7 +1454,8 @@ bool AtomicExpandImpl::expandAtomicCmpXchg(AtomicCmpXchgInst *CI) {

// If the cmpxchg doesn't actually need any ordering when it fails, we can
// jump straight past that fence instruction (if it exists).
Builder.CreateCondBr(ShouldStore, ReleasingStoreBB, NoStoreBB);
Builder.CreateCondBr(ShouldStore, ReleasingStoreBB, NoStoreBB,
MDBuilder(F->getContext()).createLikelyBranchWeights());

Builder.SetInsertPoint(ReleasingStoreBB);
if (ShouldInsertFencesForAtomic && !UseUnconditionalReleaseBarrier)
Expand All @@ -1473,7 +1474,8 @@ bool AtomicExpandImpl::expandAtomicCmpXchg(AtomicCmpXchgInst *CI) {
StoreSuccess, ConstantInt::get(Type::getInt32Ty(Ctx), 0), "success");
BasicBlock *RetryBB = HasReleasedLoadBB ? ReleasedLoadBB : StartBB;
Builder.CreateCondBr(StoreSuccess, SuccessBB,
CI->isWeak() ? FailureBB : RetryBB);
CI->isWeak() ? FailureBB : RetryBB,
MDBuilder(F->getContext()).createLikelyBranchWeights());

Builder.SetInsertPoint(ReleasedLoadBB);
Value *SecondLoad;
Expand All @@ -1486,7 +1488,9 @@ bool AtomicExpandImpl::expandAtomicCmpXchg(AtomicCmpXchgInst *CI) {

// If the cmpxchg doesn't actually need any ordering when it fails, we can
// jump straight past that fence instruction (if it exists).
Builder.CreateCondBr(ShouldStore, TryStoreBB, NoStoreBB);
Builder.CreateCondBr(
ShouldStore, TryStoreBB, NoStoreBB,
MDBuilder(F->getContext()).createLikelyBranchWeights());
// Update PHI node in TryStoreBB.
LoadedTryStore->addIncoming(SecondLoad, ReleasedLoadBB);
} else
Expand Down
60 changes: 35 additions & 25 deletions llvm/test/CodeGen/AArch64/GlobalISel/arm64-atomic.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -6002,15 +6002,17 @@ define { i8, i1 } @cmpxchg_i8(ptr %ptr, i8 %desired, i8 %new) {
; CHECK-NOLSE-O1-NEXT: b.ne LBB67_4
; CHECK-NOLSE-O1-NEXT: ; %bb.2: ; %cmpxchg.trystore
; CHECK-NOLSE-O1-NEXT: ; in Loop: Header=BB67_1 Depth=1
; CHECK-NOLSE-O1-NEXT: stxrb w9, w2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w9, LBB67_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3:
; CHECK-NOLSE-O1-NEXT: mov w1, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: stxrb w10, w2, [x8]
; CHECK-NOLSE-O1-NEXT: mov w9, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: cbnz w10, LBB67_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3: ; %cmpxchg.end
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ; kill: def $w0 killed $w0 killed $x0
; CHECK-NOLSE-O1-NEXT: ret
; CHECK-NOLSE-O1-NEXT: LBB67_4: ; %cmpxchg.nostore
; CHECK-NOLSE-O1-NEXT: mov w1, wzr
; CHECK-NOLSE-O1-NEXT: mov w9, wzr
; CHECK-NOLSE-O1-NEXT: clrex
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ; kill: def $w0 killed $w0 killed $x0
; CHECK-NOLSE-O1-NEXT: ret
;
Expand Down Expand Up @@ -6108,15 +6110,17 @@ define { i16, i1 } @cmpxchg_i16(ptr %ptr, i16 %desired, i16 %new) {
; CHECK-NOLSE-O1-NEXT: b.ne LBB68_4
; CHECK-NOLSE-O1-NEXT: ; %bb.2: ; %cmpxchg.trystore
; CHECK-NOLSE-O1-NEXT: ; in Loop: Header=BB68_1 Depth=1
; CHECK-NOLSE-O1-NEXT: stxrh w9, w2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w9, LBB68_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3:
; CHECK-NOLSE-O1-NEXT: mov w1, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: stxrh w10, w2, [x8]
; CHECK-NOLSE-O1-NEXT: mov w9, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: cbnz w10, LBB68_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3: ; %cmpxchg.end
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ; kill: def $w0 killed $w0 killed $x0
; CHECK-NOLSE-O1-NEXT: ret
; CHECK-NOLSE-O1-NEXT: LBB68_4: ; %cmpxchg.nostore
; CHECK-NOLSE-O1-NEXT: mov w1, wzr
; CHECK-NOLSE-O1-NEXT: mov w9, wzr
; CHECK-NOLSE-O1-NEXT: clrex
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ; kill: def $w0 killed $w0 killed $x0
; CHECK-NOLSE-O1-NEXT: ret
;
Expand Down Expand Up @@ -6206,22 +6210,24 @@ define { i32, i1 } @cmpxchg_i32(ptr %ptr, i32 %desired, i32 %new) {
; CHECK-NOLSE-O1-LABEL: cmpxchg_i32:
; CHECK-NOLSE-O1: ; %bb.0:
; CHECK-NOLSE-O1-NEXT: mov x8, x0
; CHECK-NOLSE-O1-NEXT: mov w9, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: LBB69_1: ; %cmpxchg.start
; CHECK-NOLSE-O1-NEXT: ; =>This Inner Loop Header: Depth=1
; CHECK-NOLSE-O1-NEXT: ldxr w0, [x8]
; CHECK-NOLSE-O1-NEXT: cmp w0, w1
; CHECK-NOLSE-O1-NEXT: b.ne LBB69_4
; CHECK-NOLSE-O1-NEXT: ; %bb.2: ; %cmpxchg.trystore
; CHECK-NOLSE-O1-NEXT: ; in Loop: Header=BB69_1 Depth=1
; CHECK-NOLSE-O1-NEXT: stxr w9, w2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w9, LBB69_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3:
; CHECK-NOLSE-O1-NEXT: mov w1, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: stxr w10, w2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w10, LBB69_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3: ; %cmpxchg.end
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ; kill: def $w0 killed $w0 killed $x0
; CHECK-NOLSE-O1-NEXT: ret
; CHECK-NOLSE-O1-NEXT: LBB69_4: ; %cmpxchg.nostore
; CHECK-NOLSE-O1-NEXT: mov w1, wzr
; CHECK-NOLSE-O1-NEXT: mov w9, wzr
; CHECK-NOLSE-O1-NEXT: clrex
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ; kill: def $w0 killed $w0 killed $x0
; CHECK-NOLSE-O1-NEXT: ret
;
Expand Down Expand Up @@ -6306,21 +6312,23 @@ define { i64, i1 } @cmpxchg_i64(ptr %ptr, i64 %desired, i64 %new) {
; CHECK-NOLSE-O1-LABEL: cmpxchg_i64:
; CHECK-NOLSE-O1: ; %bb.0:
; CHECK-NOLSE-O1-NEXT: mov x8, x0
; CHECK-NOLSE-O1-NEXT: mov w9, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: LBB70_1: ; %cmpxchg.start
; CHECK-NOLSE-O1-NEXT: ; =>This Inner Loop Header: Depth=1
; CHECK-NOLSE-O1-NEXT: ldxr x0, [x8]
; CHECK-NOLSE-O1-NEXT: cmp x0, x1
; CHECK-NOLSE-O1-NEXT: b.ne LBB70_4
; CHECK-NOLSE-O1-NEXT: ; %bb.2: ; %cmpxchg.trystore
; CHECK-NOLSE-O1-NEXT: ; in Loop: Header=BB70_1 Depth=1
; CHECK-NOLSE-O1-NEXT: stxr w9, x2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w9, LBB70_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3:
; CHECK-NOLSE-O1-NEXT: mov w1, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: stxr w10, x2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w10, LBB70_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3: ; %cmpxchg.end
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ret
; CHECK-NOLSE-O1-NEXT: LBB70_4: ; %cmpxchg.nostore
; CHECK-NOLSE-O1-NEXT: mov w1, wzr
; CHECK-NOLSE-O1-NEXT: mov w9, wzr
; CHECK-NOLSE-O1-NEXT: clrex
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ret
;
; CHECK-OUTLINE-O1-LABEL: cmpxchg_i64:
Expand Down Expand Up @@ -6404,21 +6412,23 @@ define { ptr, i1 } @cmpxchg_ptr(ptr %ptr, ptr %desired, ptr %new) {
; CHECK-NOLSE-O1-LABEL: cmpxchg_ptr:
; CHECK-NOLSE-O1: ; %bb.0:
; CHECK-NOLSE-O1-NEXT: mov x8, x0
; CHECK-NOLSE-O1-NEXT: mov w9, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: LBB71_1: ; %cmpxchg.start
; CHECK-NOLSE-O1-NEXT: ; =>This Inner Loop Header: Depth=1
; CHECK-NOLSE-O1-NEXT: ldxr x0, [x8]
; CHECK-NOLSE-O1-NEXT: cmp x0, x1
; CHECK-NOLSE-O1-NEXT: b.ne LBB71_4
; CHECK-NOLSE-O1-NEXT: ; %bb.2: ; %cmpxchg.trystore
; CHECK-NOLSE-O1-NEXT: ; in Loop: Header=BB71_1 Depth=1
; CHECK-NOLSE-O1-NEXT: stxr w9, x2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w9, LBB71_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3:
; CHECK-NOLSE-O1-NEXT: mov w1, #1 ; =0x1
; CHECK-NOLSE-O1-NEXT: stxr w10, x2, [x8]
; CHECK-NOLSE-O1-NEXT: cbnz w10, LBB71_1
; CHECK-NOLSE-O1-NEXT: ; %bb.3: ; %cmpxchg.end
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ret
; CHECK-NOLSE-O1-NEXT: LBB71_4: ; %cmpxchg.nostore
; CHECK-NOLSE-O1-NEXT: mov w1, wzr
; CHECK-NOLSE-O1-NEXT: mov w9, wzr
; CHECK-NOLSE-O1-NEXT: clrex
; CHECK-NOLSE-O1-NEXT: mov w1, w9
; CHECK-NOLSE-O1-NEXT: ret
;
; CHECK-OUTLINE-O1-LABEL: cmpxchg_ptr:
Expand Down
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