[PATCH] D158962: [RISCV] Prevent tryToFoldBNEOnCmpXchgResult from deleting AND if has t others users.

[Craig Topper via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGff6d33382faf: [RISCV] Prevent tryToFoldBNEOnCmpXchgResult from deleting AND if it has others… (authored by craig.topper).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D158962/new/

https://reviews.llvm.org/D158962

Files:
  llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
  llvm/test/CodeGen/RISCV/pr65025.ll


Index: llvm/test/CodeGen/RISCV/pr65025.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/RISCV/pr65025.ll
@@ -0,0 +1,48 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s -mtriple=riscv64 -mattr=+a | FileCheck %s
+
+define ptr @cmpxchg_masked_and_branch1(ptr %ptr, i8 signext %cmp, i8 signext %val) nounwind {
+; CHECK-LABEL: cmpxchg_masked_and_branch1:
+; CHECK:       # %bb.0: # %do_cmpxchg
+; CHECK-NEXT:    andi a3, a0, -4
+; CHECK-NEXT:    slli a4, a0, 3
+; CHECK-NEXT:    li a5, 255
+; CHECK-NEXT:    sllw a5, a5, a4
+; CHECK-NEXT:    andi a1, a1, 255
+; CHECK-NEXT:    sllw a1, a1, a4
+; CHECK-NEXT:    andi a2, a2, 255
+; CHECK-NEXT:    sllw a2, a2, a4
+; CHECK-NEXT:  .LBB0_3: # %do_cmpxchg
+; CHECK-NEXT:    # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:    lr.w.aqrl a4, (a3)
+; CHECK-NEXT:    and a6, a4, a5
+; CHECK-NEXT:    bne a6, a1, .LBB0_5
+; CHECK-NEXT:  # %bb.4: # %do_cmpxchg
+; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=1
+; CHECK-NEXT:    xor a6, a4, a2
+; CHECK-NEXT:    and a6, a6, a5
+; CHECK-NEXT:    xor a6, a4, a6
+; CHECK-NEXT:    sc.w.rl a6, a6, (a3)
+; CHECK-NEXT:    bnez a6, .LBB0_3
+; CHECK-NEXT:  .LBB0_5: # %do_cmpxchg
+; CHECK-NEXT:    and a2, a4, a5
+; CHECK-NEXT:    bne a1, a2, .LBB0_2
+; CHECK-NEXT:  # %bb.1: # %returnptr
+; CHECK-NEXT:    xor a1, a1, a2
+; CHECK-NEXT:    snez a1, a1
+; CHECK-NEXT:    addi a1, a1, -1
+; CHECK-NEXT:    and a0, a1, a0
+; CHECK-NEXT:    ret
+; CHECK-NEXT:  .LBB0_2: # %exit
+; CHECK-NEXT:    li a0, 0
+; CHECK-NEXT:    ret
+do_cmpxchg:
+  %0 = cmpxchg ptr %ptr, i8 %cmp, i8 %val seq_cst seq_cst
+  %1 = extractvalue { i8, i1 } %0, 1
+  %2 = select i1 %1, ptr %ptr, ptr null
+  br i1 %1, label %returnptr, label %exit
+returnptr:
+  ret ptr %2
+exit:
+  ret ptr null
+}
Index: llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
+++ llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
@@ -601,6 +601,15 @@
   if (!(BNEOp0 == DestReg && BNEOp1 == CmpValReg) &&
       !(BNEOp0 == CmpValReg && BNEOp1 == DestReg))
     return false;
+
+  // Make sure the branch is the only user of the AND.
+  if (MaskReg.isValid()) {
+    if (BNEOp0 == DestReg && !MBBI->getOperand(0).isKill())
+      return false;
+    if (BNEOp1 == DestReg && !MBBI->getOperand(1).isKill())
+      return false;
+  }
+
   ToErase.push_back(&*MBBI);
   LoopHeadBNETarget = MBBI->getOperand(2).getMBB();
   MBBI = skipDebugInstructionsForward(std::next(MBBI), E);


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