[PATCH] D89938: [DAG][PowerPC] Do not overwrite flags in `getNodeIfExists` without passing `Flags` argument

[Kai Luo via Phabricator via llvm-commits]

lkail created this revision.
lkail added reviewers: jonpa, spatel, qiucf, efriedma, uweigand, PowerPC.
Herald added subscribers: llvm-commits, shchenz, hiraditya, nemanjai.
Herald added a project: LLVM.
lkail requested review of this revision.

`SimplifySetCC` invokes `getNodeIfExists` without passing `Flags` argument and `getNodeIfExists` uses a default `SDNodeFlags` to intersect the original flags, as a consequence, flags like `nsw` is dropped.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89938

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  llvm/test/CodeGen/PowerPC/setcc-sub-flag.ll


Index: llvm/test/CodeGen/PowerPC/setcc-sub-flag.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/setcc-sub-flag.ll
+++ llvm/test/CodeGen/PowerPC/setcc-sub-flag.ll
@@ -10,7 +10,7 @@
   ; CHECK:   liveins: $x3, $x4
   ; CHECK:   [[COPY:%[0-9]+]]:g8rc = COPY $x4
   ; CHECK:   [[COPY1:%[0-9]+]]:g8rc = COPY $x3
-  ; CHECK:   [[SUBF8_:%[0-9]+]]:g8rc = SUBF8 [[COPY1]], [[COPY]]
+  ; CHECK:   [[SUBF8_:%[0-9]+]]:g8rc = nsw SUBF8 [[COPY1]], [[COPY]]
   %c = sub nsw i64 %b, %a
   call void @foo(i64 %c)
   %d = icmp slt i64 %a, %b
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -8305,10 +8305,16 @@
 /// else return NULL.
 SDNode *SelectionDAG::getNodeIfExists(unsigned Opcode, SDVTList VTList,
                                       ArrayRef<SDValue> Ops) {
-  SDNodeFlags Flags;
   if (Inserter)
-    Flags = Inserter->getFlags();
-  return getNodeIfExists(Opcode, VTList, Ops, Flags);
+    return getNodeIfExists(Opcode, VTList, Ops, Inserter->getFlags());
+  if (VTList.VTs[VTList.NumVTs - 1] != MVT::Glue) {
+    FoldingSetNodeID ID;
+    AddNodeIDNode(ID, Opcode, VTList, Ops);
+    void *IP = nullptr;
+    if (SDNode *E = FindNodeOrInsertPos(ID, SDLoc(), IP))
+      return E;
+  }
+  return nullptr;
 }
 
 SDNode *SelectionDAG::getNodeIfExists(unsigned Opcode, SDVTList VTList,


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