diff options
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 19 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/freeze-binary.ll | 7 |
2 files changed, 11 insertions, 15 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 390ee7e..c62de47 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -14261,8 +14261,7 @@ SDValue DAGCombiner::visitFREEZE(SDNode *N) { if (DAG.isGuaranteedNotToBeUndefOrPoison(Op, /*PoisonOnly*/ false, /*Depth*/ 1)) continue; - if ((!MaybePoisonOperand && N0->isOnlyUserOf(Op.getNode())) || - MaybePoisonOperand == Op) { + if (!MaybePoisonOperand || MaybePoisonOperand == Op) { MaybePoisonOperand = Op; continue; } @@ -14271,15 +14270,17 @@ SDValue DAGCombiner::visitFREEZE(SDNode *N) { break; } if (MaybePoisonOperand) { - // Recreate the node with the frozen maybe-poison operand. - // TODO: Drop the isOnlyUserOf constraint and replace all users of - // MaybePoisonOperand with FrozenMaybePoisonOperand - // to match pushFreezeToPreventPoisonFromPropagating behavior. + // First, freeze the offending operand. SDValue FrozenMaybePoisonOperand = DAG.getFreeze(MaybePoisonOperand); + // Then, change all other uses of unfrozen operand to use frozen operand. + DAG.ReplaceAllUsesOfValueWith(MaybePoisonOperand, + FrozenMaybePoisonOperand); + // But, that also updated the use in the freeze we just created, thus + // creating a cycle in a DAG. Let's undo that by mutating the freeze. + DAG.UpdateNodeOperands(FrozenMaybePoisonOperand.getNode(), + MaybePoisonOperand); + // Finally, recreate the node with the frozen maybe-poison operand. SmallVector<SDValue> Ops(N0->op_begin(), N0->op_end()); - for (SDValue &Op : Ops) - if (Op == MaybePoisonOperand) - Op = FrozenMaybePoisonOperand; // TODO: Just strip poison generating flags? SDValue R = DAG.getNode(N0.getOpcode(), SDLoc(N0), N0->getVTList(), Ops); assert(DAG.isGuaranteedNotToBeUndefOrPoison(R, /*PoisonOnly*/ false) && diff --git a/llvm/test/CodeGen/X86/freeze-binary.ll b/llvm/test/CodeGen/X86/freeze-binary.ll index 0f3e2fb..339f1f9 100644 --- a/llvm/test/CodeGen/X86/freeze-binary.ll +++ b/llvm/test/CodeGen/X86/freeze-binary.ll @@ -26,7 +26,6 @@ define i32 @freeze_and_extra_use(i32 %a0, ptr %escape) nounwind { ; X86-NEXT: movl {{[0-9]+}}(%esp), %eax ; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx ; X86-NEXT: movl %eax, (%ecx) -; X86-NEXT: andl $15, %eax ; X86-NEXT: andl $7, %eax ; X86-NEXT: retl ; @@ -34,7 +33,6 @@ define i32 @freeze_and_extra_use(i32 %a0, ptr %escape) nounwind { ; X64: # %bb.0: ; X64-NEXT: movl %edi, %eax ; X64-NEXT: movl %edi, (%rsi) -; X64-NEXT: andl $15, %eax ; X64-NEXT: andl $7, %eax ; X64-NEXT: retq store i32 %a0, ptr %escape @@ -46,17 +44,14 @@ define i32 @freeze_and_extra_use(i32 %a0, ptr %escape) nounwind { define i32 @freeze_and_extra_use2(i32 %a0, ptr %escape) nounwind { ; X86-LABEL: freeze_and_extra_use2: ; X86: # %bb.0: -; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx -; X86-NEXT: movl %ecx, %eax +; X86-NEXT: movl {{[0-9]+}}(%esp), %eax ; X86-NEXT: andl $15, %eax -; X86-NEXT: andl %ecx, %eax ; X86-NEXT: retl ; ; X64-LABEL: freeze_and_extra_use2: ; X64: # %bb.0: ; X64-NEXT: movl %edi, %eax ; X64-NEXT: andl $15, %eax -; X64-NEXT: andl %edi, %eax ; X64-NEXT: retq %x = and i32 %a0, 15 %y = freeze i32 %x |