[PowecPC] Hint branch `bne-` for atomic operation after the store-conditional #152529

diggerlin · 2025-08-07T15:16:01Z

The branches emitted for atomic operations after the store-conditional are currently not hinted, even though they should be.

According to the Power10 Processor Chip User’s Manual:

“Without static prediction, if the lock is not acquired in the first iteration, the branch history mechanism works to update the prediction to predict taken; that is, predict lock acquisition failure and cause more lwarx traffic for the next iteration.”

This patch addresses the issue by adding explicit branch hints for atomic operations after the store-conditional.

llvmbot · 2025-08-07T15:16:39Z

@llvm/pr-subscribers-backend-powerpc

Author: zhijian lin (diggerlin)

Changes

The branches emitted for atomic operations are currently not hinted, even though they should be.

According to the Power10 Processor Chip User’s Manual:

“Without static prediction, if the lock is not acquired in the first iteration, the branch history mechanism works to update the prediction to predict taken; that is, predict lock acquisition failure and cause more lwarx traffic for the next iteration.”

This patch addresses the issue by adding explicit branch hints for atomic operations.

Patch is 256.08 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/152529.diff

8 Files Affected:

(modified) llvm/lib/Target/PowerPC/PPCISelLowering.cpp (+4-4)
(modified) llvm/test/CodeGen/PowerPC/all-atomics.ll (+281-281)
(modified) llvm/test/CodeGen/PowerPC/atomic-minmax.ll (+24-24)
(modified) llvm/test/CodeGen/PowerPC/atomics-regression.ll (+440-440)
(modified) llvm/test/CodeGen/PowerPC/atomics.ll (+61-61)
(modified) llvm/test/CodeGen/PowerPC/ppc-partword-atomic.ll (+4-4)
(modified) llvm/test/CodeGen/PowerPC/pr61882.ll (+2-2)
(modified) llvm/test/CodeGen/PowerPC/sign-ext-atomics.ll (+3-3)

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 459525ed4ee9a..bbba6e23140b2 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -12954,7 +12954,7 @@ PPCTargetLowering::EmitAtomicBinary(MachineInstr &MI, MachineBasicBlock *BB,
   BuildMI(BB, dl, TII->get(StoreMnemonic))
     .addReg(TmpReg).addReg(ptrA).addReg(ptrB);
   BuildMI(BB, dl, TII->get(PPC::BCC))
-    .addImm(PPC::PRED_NE).addReg(PPC::CR0).addMBB(loopMBB);
+    .addImm(PPC::PRED_NE_MINUS).addReg(PPC::CR0).addMBB(loopMBB);
   BB->addSuccessor(loopMBB);
   BB->addSuccessor(exitMBB);
 
@@ -13212,7 +13212,7 @@ MachineBasicBlock *PPCTargetLowering::EmitPartwordAtomicBinary(
       .addReg(ZeroReg)
       .addReg(PtrReg);
   BuildMI(BB, dl, TII->get(PPC::BCC))
-      .addImm(PPC::PRED_NE)
+      .addImm(PPC::PRED_NE_MINUS)
       .addReg(PPC::CR0)
       .addMBB(loopMBB);
   BB->addSuccessor(loopMBB);
@@ -14043,7 +14043,7 @@ PPCTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
         .addReg(dest)
         .addReg(oldval);
     BuildMI(BB, dl, TII->get(PPC::BCC))
-        .addImm(PPC::PRED_NE)
+        .addImm(PPC::PRED_NE_MINUS)
         .addReg(CrReg)
         .addMBB(exitMBB);
     BB->addSuccessor(loop2MBB);
@@ -14055,7 +14055,7 @@ PPCTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
         .addReg(ptrA)
         .addReg(ptrB);
     BuildMI(BB, dl, TII->get(PPC::BCC))
-        .addImm(PPC::PRED_NE)
+        .addImm(PPC::PRED_NE_MINUS)
         .addReg(PPC::CR0)
         .addMBB(loop1MBB);
     BuildMI(BB, dl, TII->get(PPC::B)).addMBB(exitMBB);
diff --git a/llvm/test/CodeGen/PowerPC/all-atomics.ll b/llvm/test/CodeGen/PowerPC/all-atomics.ll
index 07afea75aec67..8b9755fed43d9 100644
--- a/llvm/test/CodeGen/PowerPC/all-atomics.ll
+++ b/llvm/test/CodeGen/PowerPC/all-atomics.ll
@@ -33,7 +33,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 5, 0, 4
 ; CHECK-NEXT:    addi 5, 5, 1
 ; CHECK-NEXT:    stbcx. 5, 0, 4
-; CHECK-NEXT:    bne 0, .LBB0_1
+; CHECK-NEXT:    bne- 0, .LBB0_1
 ; CHECK-NEXT:  # %bb.2: # %entry
 ; CHECK-NEXT:    addis 5, 2, uc@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -44,7 +44,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 6, 0, 5
 ; CHECK-NEXT:    addi 6, 6, 1
 ; CHECK-NEXT:    stbcx. 6, 0, 5
-; CHECK-NEXT:    bne 0, .LBB0_3
+; CHECK-NEXT:    bne- 0, .LBB0_3
 ; CHECK-NEXT:  # %bb.4: # %entry
 ; CHECK-NEXT:    addis 6, 2, ss@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -55,7 +55,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 7, 0, 6
 ; CHECK-NEXT:    addi 7, 7, 1
 ; CHECK-NEXT:    sthcx. 7, 0, 6
-; CHECK-NEXT:    bne 0, .LBB0_5
+; CHECK-NEXT:    bne- 0, .LBB0_5
 ; CHECK-NEXT:  # %bb.6: # %entry
 ; CHECK-NEXT:    addis 7, 2, us@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -66,7 +66,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 7, 0, 8
 ; CHECK-NEXT:    addi 7, 7, 1
 ; CHECK-NEXT:    sthcx. 7, 0, 8
-; CHECK-NEXT:    bne 0, .LBB0_7
+; CHECK-NEXT:    bne- 0, .LBB0_7
 ; CHECK-NEXT:  # %bb.8: # %entry
 ; CHECK-NEXT:    addis 7, 2, si@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -77,7 +77,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 7, 0, 9
 ; CHECK-NEXT:    addi 7, 7, 1
 ; CHECK-NEXT:    stwcx. 7, 0, 9
-; CHECK-NEXT:    bne 0, .LBB0_9
+; CHECK-NEXT:    bne- 0, .LBB0_9
 ; CHECK-NEXT:  # %bb.10: # %entry
 ; CHECK-NEXT:    addis 7, 2, ui@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -88,7 +88,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 7, 0, 10
 ; CHECK-NEXT:    addi 7, 7, 1
 ; CHECK-NEXT:    stwcx. 7, 0, 10
-; CHECK-NEXT:    bne 0, .LBB0_11
+; CHECK-NEXT:    bne- 0, .LBB0_11
 ; CHECK-NEXT:  # %bb.12: # %entry
 ; CHECK-NEXT:    addis 7, 2, sll@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -100,7 +100,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 12, 0, 11
 ; CHECK-NEXT:    addi 12, 12, 1
 ; CHECK-NEXT:    stdcx. 12, 0, 11
-; CHECK-NEXT:    bne 0, .LBB0_13
+; CHECK-NEXT:    bne- 0, .LBB0_13
 ; CHECK-NEXT:  # %bb.14: # %entry
 ; CHECK-NEXT:    addis 12, 2, ull@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -111,7 +111,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 30, 0, 12
 ; CHECK-NEXT:    addi 0, 30, 1
 ; CHECK-NEXT:    stdcx. 0, 0, 12
-; CHECK-NEXT:    bne 0, .LBB0_15
+; CHECK-NEXT:    bne- 0, .LBB0_15
 ; CHECK-NEXT:  # %bb.16: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -120,7 +120,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 4
 ; CHECK-NEXT:    sub 0, 0, 3
 ; CHECK-NEXT:    stbcx. 0, 0, 4
-; CHECK-NEXT:    bne 0, .LBB0_17
+; CHECK-NEXT:    bne- 0, .LBB0_17
 ; CHECK-NEXT:  # %bb.18: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -129,7 +129,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 5
 ; CHECK-NEXT:    sub 0, 0, 3
 ; CHECK-NEXT:    stbcx. 0, 0, 5
-; CHECK-NEXT:    bne 0, .LBB0_19
+; CHECK-NEXT:    bne- 0, .LBB0_19
 ; CHECK-NEXT:  # %bb.20: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -138,7 +138,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 6
 ; CHECK-NEXT:    sub 0, 0, 3
 ; CHECK-NEXT:    sthcx. 0, 0, 6
-; CHECK-NEXT:    bne 0, .LBB0_21
+; CHECK-NEXT:    bne- 0, .LBB0_21
 ; CHECK-NEXT:  # %bb.22: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -147,7 +147,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 8
 ; CHECK-NEXT:    sub 0, 0, 3
 ; CHECK-NEXT:    sthcx. 0, 0, 8
-; CHECK-NEXT:    bne 0, .LBB0_23
+; CHECK-NEXT:    bne- 0, .LBB0_23
 ; CHECK-NEXT:  # %bb.24: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -156,7 +156,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 9
 ; CHECK-NEXT:    sub 0, 0, 3
 ; CHECK-NEXT:    stwcx. 0, 0, 9
-; CHECK-NEXT:    bne 0, .LBB0_25
+; CHECK-NEXT:    bne- 0, .LBB0_25
 ; CHECK-NEXT:  # %bb.26: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -165,7 +165,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 10
 ; CHECK-NEXT:    sub 0, 0, 3
 ; CHECK-NEXT:    stwcx. 0, 0, 10
-; CHECK-NEXT:    bne 0, .LBB0_27
+; CHECK-NEXT:    bne- 0, .LBB0_27
 ; CHECK-NEXT:  # %bb.28: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -174,7 +174,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 11
 ; CHECK-NEXT:    sub 0, 0, 7
 ; CHECK-NEXT:    stdcx. 0, 0, 11
-; CHECK-NEXT:    bne 0, .LBB0_29
+; CHECK-NEXT:    bne- 0, .LBB0_29
 ; CHECK-NEXT:  # %bb.30: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -183,7 +183,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 12
 ; CHECK-NEXT:    sub 0, 0, 7
 ; CHECK-NEXT:    stdcx. 0, 0, 12
-; CHECK-NEXT:    bne 0, .LBB0_31
+; CHECK-NEXT:    bne- 0, .LBB0_31
 ; CHECK-NEXT:  # %bb.32: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -192,7 +192,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 4
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    stbcx. 0, 0, 4
-; CHECK-NEXT:    bne 0, .LBB0_33
+; CHECK-NEXT:    bne- 0, .LBB0_33
 ; CHECK-NEXT:  # %bb.34: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -201,7 +201,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 5
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    stbcx. 0, 0, 5
-; CHECK-NEXT:    bne 0, .LBB0_35
+; CHECK-NEXT:    bne- 0, .LBB0_35
 ; CHECK-NEXT:  # %bb.36: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -210,7 +210,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 6
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    sthcx. 0, 0, 6
-; CHECK-NEXT:    bne 0, .LBB0_37
+; CHECK-NEXT:    bne- 0, .LBB0_37
 ; CHECK-NEXT:  # %bb.38: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -219,7 +219,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 8
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    sthcx. 0, 0, 8
-; CHECK-NEXT:    bne 0, .LBB0_39
+; CHECK-NEXT:    bne- 0, .LBB0_39
 ; CHECK-NEXT:  # %bb.40: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -228,7 +228,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 9
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    stwcx. 0, 0, 9
-; CHECK-NEXT:    bne 0, .LBB0_41
+; CHECK-NEXT:    bne- 0, .LBB0_41
 ; CHECK-NEXT:  # %bb.42: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -237,7 +237,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 10
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    stwcx. 0, 0, 10
-; CHECK-NEXT:    bne 0, .LBB0_43
+; CHECK-NEXT:    bne- 0, .LBB0_43
 ; CHECK-NEXT:  # %bb.44: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -246,7 +246,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 11
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    stdcx. 0, 0, 11
-; CHECK-NEXT:    bne 0, .LBB0_45
+; CHECK-NEXT:    bne- 0, .LBB0_45
 ; CHECK-NEXT:  # %bb.46: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -255,7 +255,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 12
 ; CHECK-NEXT:    ori 0, 0, 1
 ; CHECK-NEXT:    stdcx. 0, 0, 12
-; CHECK-NEXT:    bne 0, .LBB0_47
+; CHECK-NEXT:    bne- 0, .LBB0_47
 ; CHECK-NEXT:  # %bb.48: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -264,7 +264,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 4
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    stbcx. 0, 0, 4
-; CHECK-NEXT:    bne 0, .LBB0_49
+; CHECK-NEXT:    bne- 0, .LBB0_49
 ; CHECK-NEXT:  # %bb.50: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -273,7 +273,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 5
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    stbcx. 0, 0, 5
-; CHECK-NEXT:    bne 0, .LBB0_51
+; CHECK-NEXT:    bne- 0, .LBB0_51
 ; CHECK-NEXT:  # %bb.52: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -282,7 +282,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 6
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    sthcx. 0, 0, 6
-; CHECK-NEXT:    bne 0, .LBB0_53
+; CHECK-NEXT:    bne- 0, .LBB0_53
 ; CHECK-NEXT:  # %bb.54: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -291,7 +291,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 8
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    sthcx. 0, 0, 8
-; CHECK-NEXT:    bne 0, .LBB0_55
+; CHECK-NEXT:    bne- 0, .LBB0_55
 ; CHECK-NEXT:  # %bb.56: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -300,7 +300,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 9
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    stwcx. 0, 0, 9
-; CHECK-NEXT:    bne 0, .LBB0_57
+; CHECK-NEXT:    bne- 0, .LBB0_57
 ; CHECK-NEXT:  # %bb.58: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -309,7 +309,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 10
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    stwcx. 0, 0, 10
-; CHECK-NEXT:    bne 0, .LBB0_59
+; CHECK-NEXT:    bne- 0, .LBB0_59
 ; CHECK-NEXT:  # %bb.60: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -318,7 +318,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 11
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    stdcx. 0, 0, 11
-; CHECK-NEXT:    bne 0, .LBB0_61
+; CHECK-NEXT:    bne- 0, .LBB0_61
 ; CHECK-NEXT:  # %bb.62: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -327,7 +327,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 12
 ; CHECK-NEXT:    xori 0, 0, 1
 ; CHECK-NEXT:    stdcx. 0, 0, 12
-; CHECK-NEXT:    bne 0, .LBB0_63
+; CHECK-NEXT:    bne- 0, .LBB0_63
 ; CHECK-NEXT:  # %bb.64: # %entry
 ; CHECK-NEXT:    addis 30, 2, u128@toc@ha
 ; CHECK-NEXT:    lwsync
@@ -361,7 +361,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 4
 ; CHECK-NEXT:    nand 0, 3, 0
 ; CHECK-NEXT:    stbcx. 0, 0, 4
-; CHECK-NEXT:    bne 0, .LBB0_69
+; CHECK-NEXT:    bne- 0, .LBB0_69
 ; CHECK-NEXT:  # %bb.70: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -370,7 +370,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 5
 ; CHECK-NEXT:    nand 0, 3, 0
 ; CHECK-NEXT:    stbcx. 0, 0, 5
-; CHECK-NEXT:    bne 0, .LBB0_71
+; CHECK-NEXT:    bne- 0, .LBB0_71
 ; CHECK-NEXT:  # %bb.72: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -379,7 +379,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 6
 ; CHECK-NEXT:    nand 0, 3, 0
 ; CHECK-NEXT:    sthcx. 0, 0, 6
-; CHECK-NEXT:    bne 0, .LBB0_73
+; CHECK-NEXT:    bne- 0, .LBB0_73
 ; CHECK-NEXT:  # %bb.74: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -388,7 +388,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 0, 0, 8
 ; CHECK-NEXT:    nand 0, 3, 0
 ; CHECK-NEXT:    sthcx. 0, 0, 8
-; CHECK-NEXT:    bne 0, .LBB0_75
+; CHECK-NEXT:    bne- 0, .LBB0_75
 ; CHECK-NEXT:  # %bb.76: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -397,7 +397,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 9
 ; CHECK-NEXT:    nand 0, 3, 0
 ; CHECK-NEXT:    stwcx. 0, 0, 9
-; CHECK-NEXT:    bne 0, .LBB0_77
+; CHECK-NEXT:    bne- 0, .LBB0_77
 ; CHECK-NEXT:  # %bb.78: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -406,7 +406,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 0, 0, 10
 ; CHECK-NEXT:    nand 0, 3, 0
 ; CHECK-NEXT:    stwcx. 0, 0, 10
-; CHECK-NEXT:    bne 0, .LBB0_79
+; CHECK-NEXT:    bne- 0, .LBB0_79
 ; CHECK-NEXT:  # %bb.80: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -415,7 +415,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 11
 ; CHECK-NEXT:    nand 0, 7, 0
 ; CHECK-NEXT:    stdcx. 0, 0, 11
-; CHECK-NEXT:    bne 0, .LBB0_81
+; CHECK-NEXT:    bne- 0, .LBB0_81
 ; CHECK-NEXT:  # %bb.82: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -424,7 +424,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 0, 0, 12
 ; CHECK-NEXT:    nand 0, 7, 0
 ; CHECK-NEXT:    stdcx. 0, 0, 12
-; CHECK-NEXT:    bne 0, .LBB0_83
+; CHECK-NEXT:    bne- 0, .LBB0_83
 ; CHECK-NEXT:  # %bb.84: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -433,7 +433,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 0, 0, 4
 ; CHECK-NEXT:    and 0, 3, 0
 ; CHECK-NEXT:    stbcx. 0, 0, 4
-; CHECK-NEXT:    bne 0, .LBB0_85
+; CHECK-NEXT:    bne- 0, .LBB0_85
 ; CHECK-NEXT:  # %bb.86: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -442,7 +442,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lbarx 4, 0, 5
 ; CHECK-NEXT:    and 4, 3, 4
 ; CHECK-NEXT:    stbcx. 4, 0, 5
-; CHECK-NEXT:    bne 0, .LBB0_87
+; CHECK-NEXT:    bne- 0, .LBB0_87
 ; CHECK-NEXT:  # %bb.88: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -451,7 +451,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 4, 0, 6
 ; CHECK-NEXT:    and 4, 3, 4
 ; CHECK-NEXT:    sthcx. 4, 0, 6
-; CHECK-NEXT:    bne 0, .LBB0_89
+; CHECK-NEXT:    bne- 0, .LBB0_89
 ; CHECK-NEXT:  # %bb.90: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -460,7 +460,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lharx 4, 0, 8
 ; CHECK-NEXT:    and 4, 3, 4
 ; CHECK-NEXT:    sthcx. 4, 0, 8
-; CHECK-NEXT:    bne 0, .LBB0_91
+; CHECK-NEXT:    bne- 0, .LBB0_91
 ; CHECK-NEXT:  # %bb.92: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -469,7 +469,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 4, 0, 9
 ; CHECK-NEXT:    and 4, 3, 4
 ; CHECK-NEXT:    stwcx. 4, 0, 9
-; CHECK-NEXT:    bne 0, .LBB0_93
+; CHECK-NEXT:    bne- 0, .LBB0_93
 ; CHECK-NEXT:  # %bb.94: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -478,7 +478,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    lwarx 4, 0, 10
 ; CHECK-NEXT:    and 4, 3, 4
 ; CHECK-NEXT:    stwcx. 4, 0, 10
-; CHECK-NEXT:    bne 0, .LBB0_95
+; CHECK-NEXT:    bne- 0, .LBB0_95
 ; CHECK-NEXT:  # %bb.96: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -487,7 +487,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 3, 0, 11
 ; CHECK-NEXT:    and 3, 7, 3
 ; CHECK-NEXT:    stdcx. 3, 0, 11
-; CHECK-NEXT:    bne 0, .LBB0_97
+; CHECK-NEXT:    bne- 0, .LBB0_97
 ; CHECK-NEXT:  # %bb.98: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    sync
@@ -496,7 +496,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; CHECK-NEXT:    ldarx 3, 0, 12
 ; CHECK-NEXT:    and 3, 7, 3
 ; CHECK-NEXT:    stdcx. 3, 0, 12
-; CHECK-NEXT:    bne 0, .LBB0_99
+; CHECK-NEXT:    bne- 0, .LBB0_99
 ; CHECK-NEXT:  # %bb.100: # %entry
 ; CHECK-NEXT:    lwsync
 ; CHECK-NEXT:    ld 30, -16(1) # 8-byte Folded Reload
@@ -545,7 +545,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    and 5, 5, 3
 ; AIX32-NEXT:    or 4, 5, 4
 ; AIX32-NEXT:    stwcx. 4, 0, 28
-; AIX32-NEXT:    bne 0, L..BB0_1
+; AIX32-NEXT:    bne- 0, L..BB0_1
 ; AIX32-NEXT:  # %bb.2: # %entry
 ; AIX32-NEXT:    lwz 3, L..C1(2) # @uc
 ; AIX32-NEXT:    lwsync
@@ -564,7 +564,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    and 5, 5, 3
 ; AIX32-NEXT:    or 4, 5, 4
 ; AIX32-NEXT:    stwcx. 4, 0, 27
-; AIX32-NEXT:    bne 0, L..BB0_3
+; AIX32-NEXT:    bne- 0, L..BB0_3
 ; AIX32-NEXT:  # %bb.4: # %entry
 ; AIX32-NEXT:    lwz 3, L..C2(2) # @ss
 ; AIX32-NEXT:    lwsync
@@ -584,7 +584,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    and 5, 5, 3
 ; AIX32-NEXT:    or 4, 5, 4
 ; AIX32-NEXT:    stwcx. 4, 0, 25
-; AIX32-NEXT:    bne 0, L..BB0_5
+; AIX32-NEXT:    bne- 0, L..BB0_5
 ; AIX32-NEXT:  # %bb.6: # %entry
 ; AIX32-NEXT:    lwz 3, L..C3(2) # @us
 ; AIX32-NEXT:    lwsync
@@ -604,7 +604,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    and 5, 5, 3
 ; AIX32-NEXT:    or 4, 5, 4
 ; AIX32-NEXT:    stwcx. 4, 0, 23
-; AIX32-NEXT:    bne 0, L..BB0_7
+; AIX32-NEXT:    bne- 0, L..BB0_7
 ; AIX32-NEXT:  # %bb.8: # %entry
 ; AIX32-NEXT:    lwsync
 ; AIX32-NEXT:    lwz 20, L..C4(2) # @si
@@ -614,7 +614,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    lwarx 3, 0, 20
 ; AIX32-NEXT:    addi 3, 3, 1
 ; AIX32-NEXT:    stwcx. 3, 0, 20
-; AIX32-NEXT:    bne 0, L..BB0_9
+; AIX32-NEXT:    bne- 0, L..BB0_9
 ; AIX32-NEXT:  # %bb.10: # %entry
 ; AIX32-NEXT:    lwsync
 ; AIX32-NEXT:    lwz 19, L..C5(2) # @ui
@@ -624,7 +624,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    lwarx 3, 0, 19
 ; AIX32-NEXT:    addi 3, 3, 1
 ; AIX32-NEXT:    stwcx. 3, 0, 19
-; AIX32-NEXT:    bne 0, L..BB0_11
+; AIX32-NEXT:    bne- 0, L..BB0_11
 ; AIX32-NEXT:  # %bb.12: # %entry
 ; AIX32-NEXT:    lwz 31, L..C6(2) # @sll
 ; AIX32-NEXT:    lwsync
@@ -652,7 +652,7 @@ define dso_local void @test_op_ignore() local_unnamed_addr #0 {
 ; AIX32-NEXT:    and 5, 5, 3
 ; AIX32-NEXT:    or 4, 5, 4
 ; AIX32-NEXT:    stwcx. 4, 0, 28
-; AIX32-NEXT:    bne 0, L..BB0_13
+; AIX32-NEXT:    bne- 0, L..BB0_13
 ; AIX32-NEXT:  # %bb.14: # %entry
 ; AIX32-NEXT:    li 3, 255
 ; AIX32-NEXT:    lwsync
@@ -666,7 +666,7 @@ define dso_local void @test...
[truncated]

github-actions · 2025-08-07T15:18:19Z

✅ With the latest revision this PR passed the C/C++ code formatter.

diggerlin · 2025-09-24T15:02:09Z

Whenever you have time, I’d be grateful for any feedback on the patch.

…atic prediction is honored

amy-kwan

A couple potentially silly questions:

Does this only concern PRED_NE? Should we indicate that in the PR title?
How do we determine which PRED_NEs we want the hint for, as there are other PRED_NEs beyond what is in this PR?

diggerlin · 2025-10-16T17:11:10Z

A couple potentially silly questions:

Does this only concern PRED_NE? Should we indicate that in the PR title?

How do we determine which PRED_NEs we want the hint for, as there are other PRED_NEs beyond what is in this PR?

the PR only concern about the bne- after st*cx instruction. according to the power ISA B.1 Atomic Update Primitives , it always use the bne- after st*cx. and according to the comments of the source code(for example : https://github.com/llvm/llvm-project/pull/152529/files#diff-909a72141a3ecd6bfde54a6344f80d2a194c3eb79622c5845f6c7c119145af6fR13024 ) , it should be use bne- instead of bne

amy-kwan

Thanks for the explanation, @diggerlin. Makes sense, so LGTM.

nemanjai · 2025-10-17T03:52:46Z

I think Amy's suggestion to add to the commit message that this adds the hint on the branch after the store-conditional makes sense.

diggerlin requested review from RolandF77, amy-kwan, hubert-reinterpretcast, lei137 and nemanjai August 7, 2025 15:16

llvmbot added the backend:PowerPC label Aug 7, 2025

diggerlin requested a review from kamaub September 16, 2025 14:48

diggerlin added 2 commits September 24, 2025 15:59

hardware detects a l*arx instruction near a static prediction, the st…

5df707c

…atic prediction is honored

git clang format

e0de2ae

diggerlin force-pushed the digger/hint-honor branch from 12e946b to fbd49b0 Compare September 24, 2025 17:27

change test case

fbd49b0

amy-kwan reviewed Oct 2, 2025

View reviewed changes

diggerlin changed the title ~~[PowecPC] Hint branch for atomic operation~~ [PowecPC] Hint branch bne- for atomic operation Oct 16, 2025

amy-kwan approved these changes Oct 16, 2025

View reviewed changes

diggerlin changed the title ~~[PowecPC] Hint branch bne- for atomic operation~~ [PowecPC] Hint branch bne- for atomic operation after the store-conditional Oct 20, 2025

diggerlin merged commit 7aa6c62 into llvm:main Oct 21, 2025
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[PowecPC] Hint branch `bne-` for atomic operation after the store-conditional #152529

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[PowecPC] Hint branch `bne-` for atomic operation after the store-conditional #152529

[PowecPC] Hint branch `bne-` for atomic operation after the store-conditional #152529

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