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Revert "[SelectionDAG] Introducing a new ISD::POISON SDNode to represent the poison value in the IR." #135060

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merged 1 commit into from
Apr 9, 2025
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Revert "[SelectionDAG] Introducing a new ISD::POISON SDNode to represent the poison value in the IR." #135060

merged 1 commit into from
Apr 9, 2025

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@kuhar kuhar commented Apr 9, 2025 •
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Reverts #125883

This PR causes crashes in RISC-V codegen around f16/f64 poison values: #125883 (comment)

@kuhar kuhar added the skip-precommit-approval PR for CI feedback, not intended for review label Apr 9, 2025
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llvmbot commented Apr 9, 2025 •
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@llvm/pr-subscribers-backend-x86
@llvm/pr-subscribers-llvm-selectiondag

@llvm/pr-subscribers-backend-aarch64

Author: Jakub Kuderski (kuhar)

Changes

Reverts llvm/llvm-project#125883

This PR causes crashes in RISC-V codegen around f16/f64 poison values: #125883 (comment)

Patch is 25.68 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/135060.diff

15 Files Affected:

  • (modified) llvm/include/llvm/CodeGen/ISDOpcodes.h (-3)
  • (modified) llvm/include/llvm/CodeGen/SelectionDAG.h (-3)
  • (modified) llvm/include/llvm/CodeGen/SelectionDAGNodes.h (+2-4)
  • (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+1-2)
  • (modified) llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp (-14)
  • (modified) llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp (-1)
  • (modified) llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp (-2)
  • (modified) llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp (-3)
  • (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (-3)
  • (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (+1-1)
  • (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp (-1)
  • (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (-1)
  • (modified) llvm/test/CodeGen/AArch64/vector-insert-dag-combines.ll (+19-19)
  • (modified) llvm/test/CodeGen/X86/half.ll (+12-12)
  • (modified) llvm/test/CodeGen/X86/pr119158.ll (+3-4)
diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
index ad8a95a353b56..59f31f8443947 100644
--- a/llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -217,9 +217,6 @@ enum NodeType {
   /// UNDEF - An undefined node.
   UNDEF,
 
-  /// POISON - A poison node.
-  POISON,
-
   /// FREEZE - FREEZE(VAL) returns an arbitrary value if VAL is UNDEF (or
   /// is evaluated to UNDEF), or returns VAL otherwise. Note that each
   /// read of UNDEF can yield different value, but FREEZE(UNDEF) cannot.
diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 63423463eeee2..d06e2b19fa0b5 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -1130,9 +1130,6 @@ class SelectionDAG {
     return getNode(ISD::UNDEF, SDLoc(), VT);
   }
 
-  /// Return a POISON node. POISON does not have a useful SDLoc.
-  SDValue getPOISON(EVT VT) { return getNode(ISD::POISON, SDLoc(), VT); }
-
   /// Return a node that represents the runtime scaling 'MulImm * RuntimeVL'.
   SDValue getVScale(const SDLoc &DL, EVT VT, APInt MulImm,
                     bool ConstantFold = true);
diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
index b62cf08693f63..2283f99202e2f 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -692,10 +692,8 @@ END_TWO_BYTE_PACK()
   /// \<target\>ISD namespace).
   bool isTargetOpcode() const { return NodeType >= ISD::BUILTIN_OP_END; }
 
-  /// Returns true if the node type is UNDEF or POISON.
-  bool isUndef() const {
-    return NodeType == ISD::UNDEF || NodeType == ISD::POISON;
-  }
+  /// Return true if the type of the node type undefined.
+  bool isUndef() const { return NodeType == ISD::UNDEF; }
 
   /// Test if this node is a memory intrinsic (with valid pointer information).
   bool isMemIntrinsic() const { return SDNodeBits.IsMemIntrinsic; }
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 38376de5783ae..8136f1794775e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -16287,8 +16287,7 @@ SDValue DAGCombiner::visitFREEZE(SDNode *N) {
   // Finally, recreate the node, it's operands were updated to use
   // frozen operands, so we just need to use it's "original" operands.
   SmallVector<SDValue> Ops(N0->ops());
-  // TODO: ISD::UNDEF and ISD::POISON should get separate handling, but best
-  // leave for a future patch.
+  // Special-handle ISD::UNDEF, each single one of them can be it's own thing.
   for (SDValue &Op : Ops) {
     if (Op.isUndef())
       Op = DAG.getFreeze(Op);
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index b8af281e1c24b..754c29b6ba868 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -986,19 +986,6 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
   TargetLowering::LegalizeAction Action = TargetLowering::Legal;
   bool SimpleFinishLegalizing = true;
   switch (Node->getOpcode()) {
-  // TODO: Currently, POISON is being lowered to UNDEF here. However, there is
-  // an open concern that this transformation may not be ideal, as targets
-  // should ideally handle POISON directly. Changing this behavior would require
-  // adding support for POISON in TableGen, which is a large change.
-  // Additionally, many existing test cases rely on the current behavior (e.g.,
-  // llvm/test/CodeGen/PowerPC/vec_shuffle.ll). A broader discussion and
-  // incremental changes might be needed to properly
-  // support POISON without breaking existing targets and tests.
-  case ISD::POISON: {
-    SDValue UndefNode = DAG.getUNDEF(Node->getValueType(0));
-    ReplaceNode(Node, UndefNode.getNode());
-    break;
-  }
   case ISD::INTRINSIC_W_CHAIN:
   case ISD::INTRINSIC_WO_CHAIN:
   case ISD::INTRINSIC_VOID:
@@ -3182,7 +3169,6 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     for (unsigned i = 0; i < Node->getNumValues(); i++)
       Results.push_back(Node->getOperand(i));
     break;
-  case ISD::POISON:
   case ISD::UNDEF: {
     EVT VT = Node->getValueType(0);
     if (VT.isInteger())
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
index 5ed83060e150e..01751dfe9eb62 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
@@ -2845,7 +2845,6 @@ void DAGTypeLegalizer::PromoteFloatResult(SDNode *N, unsigned ResNo) {
 
     case ISD::SINT_TO_FP:
     case ISD::UINT_TO_FP: R = PromoteFloatRes_XINT_TO_FP(N); break;
-    case ISD::POISON:
     case ISD::UNDEF:      R = PromoteFloatRes_UNDEF(N); break;
     case ISD::ATOMIC_SWAP: R = BitcastToInt_ATOMIC_SWAP(N); break;
     case ISD::VECREDUCE_FADD:
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 4685330c5aa14..d4b7283d0b0bd 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -118,7 +118,6 @@ void DAGTypeLegalizer::PromoteIntegerResult(SDNode *N, unsigned ResNo) {
   case ISD::VP_SRL:      Res = PromoteIntRes_SRL(N); break;
   case ISD::VP_TRUNCATE:
   case ISD::TRUNCATE:    Res = PromoteIntRes_TRUNCATE(N); break;
-  case ISD::POISON:
   case ISD::UNDEF:       Res = PromoteIntRes_UNDEF(N); break;
   case ISD::VAARG:       Res = PromoteIntRes_VAARG(N); break;
   case ISD::VSCALE:      Res = PromoteIntRes_VSCALE(N); break;
@@ -2915,7 +2914,6 @@ void DAGTypeLegalizer::ExpandIntegerResult(SDNode *N, unsigned ResNo) {
   case ISD::MERGE_VALUES: SplitRes_MERGE_VALUES(N, ResNo, Lo, Hi); break;
   case ISD::SELECT:       SplitRes_Select(N, Lo, Hi); break;
   case ISD::SELECT_CC:    SplitRes_SELECT_CC(N, Lo, Hi); break;
-  case ISD::POISON:
   case ISD::UNDEF:        SplitRes_UNDEF(N, Lo, Hi); break;
   case ISD::FREEZE:       SplitRes_FREEZE(N, Lo, Hi); break;
   case ISD::SETCC:        ExpandIntRes_SETCC(N, Lo, Hi); break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index f934d8b37561e..9d42ec2fdf859 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -71,7 +71,6 @@ void DAGTypeLegalizer::ScalarizeVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::SELECT:            R = ScalarizeVecRes_SELECT(N); break;
   case ISD::SELECT_CC:         R = ScalarizeVecRes_SELECT_CC(N); break;
   case ISD::SETCC:             R = ScalarizeVecRes_SETCC(N); break;
-  case ISD::POISON:
   case ISD::UNDEF:             R = ScalarizeVecRes_UNDEF(N); break;
   case ISD::VECTOR_SHUFFLE:    R = ScalarizeVecRes_VECTOR_SHUFFLE(N); break;
   case ISD::IS_FPCLASS:        R = ScalarizeVecRes_IS_FPCLASS(N); break;
@@ -1138,7 +1137,6 @@ void DAGTypeLegalizer::SplitVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::VP_MERGE:
   case ISD::VP_SELECT:    SplitRes_Select(N, Lo, Hi); break;
   case ISD::SELECT_CC:    SplitRes_SELECT_CC(N, Lo, Hi); break;
-  case ISD::POISON:
   case ISD::UNDEF:        SplitRes_UNDEF(N, Lo, Hi); break;
   case ISD::BITCAST:           SplitVecRes_BITCAST(N, Lo, Hi); break;
   case ISD::BUILD_VECTOR:      SplitVecRes_BUILD_VECTOR(N, Lo, Hi); break;
@@ -4594,7 +4592,6 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::SELECT_CC:         Res = WidenVecRes_SELECT_CC(N); break;
   case ISD::VP_SETCC:
   case ISD::SETCC:             Res = WidenVecRes_SETCC(N); break;
-  case ISD::POISON:
   case ISD::UNDEF:             Res = WidenVecRes_UNDEF(N); break;
   case ISD::VECTOR_SHUFFLE:
     Res = WidenVecRes_VECTOR_SHUFFLE(cast<ShuffleVectorSDNode>(N));
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d6dcb3f15ae7c..f2777bbf247b0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5387,9 +5387,6 @@ bool SelectionDAG::isGuaranteedNotToBeUndefOrPoison(SDValue Op,
   case ISD::CopyFromReg:
     return true;
 
-  case ISD::POISON:
-    return false;
-
   case ISD::UNDEF:
     return PoisonOnly;
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 8cae34d06c8ba..89793c30f3710 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1817,7 +1817,7 @@ SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
       return DAG.getConstantFP(*CFP, getCurSDLoc(), VT);
 
     if (isa<UndefValue>(C) && !V->getType()->isAggregateType())
-      return isa<PoisonValue>(C) ? DAG.getPOISON(VT) : DAG.getUNDEF(VT);
+      return DAG.getUNDEF(VT);
 
     if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
       visit(CE->getOpcode(), *CE);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 8fcec6c6cd7c6..958c070ed50de 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -189,7 +189,6 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   case ISD::CopyToReg:                  return "CopyToReg";
   case ISD::CopyFromReg:                return "CopyFromReg";
   case ISD::UNDEF:                      return "undef";
-  case ISD::POISON:                     return "poison";
   case ISD::VSCALE:                     return "vscale";
   case ISD::MERGE_VALUES:               return "merge_values";
   case ISD::INLINEASM:                  return "inlineasm";
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index bfbfdbc7e3ca2..1287d6ed4a764 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -3276,7 +3276,6 @@ void SelectionDAGISel::SelectCodeCommon(SDNode *NodeToMatch,
   case ISD::WRITE_REGISTER:
     Select_WRITE_REGISTER(NodeToMatch);
     return;
-  case ISD::POISON:
   case ISD::UNDEF:
     Select_UNDEF(NodeToMatch);
     return;
diff --git a/llvm/test/CodeGen/AArch64/vector-insert-dag-combines.ll b/llvm/test/CodeGen/AArch64/vector-insert-dag-combines.ll
index 5207d5cbf21a2..0e05a63ef86de 100644
--- a/llvm/test/CodeGen/AArch64/vector-insert-dag-combines.ll
+++ b/llvm/test/CodeGen/AArch64/vector-insert-dag-combines.ll
@@ -12,7 +12,7 @@ target triple = "aarch64-unknown-linux-gnu"
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: v8i8,ch = CopyFromReg t0, Register:v8i8 %0
 ; CHECK:       t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:     t6: v16i8 = insert_subvector poison:v16i8, t4, Constant:i64<0>
+; CHECK:     t6: v16i8 = insert_subvector undef:v16i8, t4, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:v16i8 $q0, t6
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:v16i8 $q0, t8:1
 
@@ -20,7 +20,7 @@ target triple = "aarch64-unknown-linux-gnu"
 ; CHECK: SelectionDAG has 9 nodes:
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:       t2: v8i8,ch = CopyFromReg t0, Register:v8i8 %0
-; CHECK:     t10: v16i8 = insert_subvector poison:v16i8, t2, Constant:i64<0>
+; CHECK:     t10: v16i8 = insert_subvector undef:v16i8, t2, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:v16i8 $q0, t10
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:v16i8 $q0, t8:1
 
@@ -35,7 +35,7 @@ define <16 x i8> @insert_small_fixed_into_big_fixed(<8 x i8> %a) #0 {
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: v8i8,ch = CopyFromReg t0, Register:v8i8 %0
 ; CHECK:       t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:     t6: nxv16i8 = insert_subvector poison:nxv16i8, t4, Constant:i64<0>
+; CHECK:     t6: nxv16i8 = insert_subvector undef:nxv16i8, t4, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:nxv16i8 $z0, t6
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:nxv16i8 $z0, t8:1
 
@@ -43,7 +43,7 @@ define <16 x i8> @insert_small_fixed_into_big_fixed(<8 x i8> %a) #0 {
 ; CHECK: SelectionDAG has 9 nodes:
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:       t2: v8i8,ch = CopyFromReg t0, Register:v8i8 %0
-; CHECK:     t10: nxv16i8 = insert_subvector poison:nxv16i8, t2, Constant:i64<0>
+; CHECK:     t10: nxv16i8 = insert_subvector undef:nxv16i8, t2, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:nxv16i8 $z0, t10
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:nxv16i8 $z0, t8:1
 
@@ -59,7 +59,7 @@ define <vscale x 16 x i8> @insert_small_fixed_into_big_scalable(<8 x i8> %a) #0
 ; CHECK:           t2: nxv8i16,ch = CopyFromReg t0, Register:nxv8i16 %0
 ; CHECK:         t3: nxv8i8 = truncate t2
 ; CHECK:       t5: v4i8 = extract_subvector t3, Constant:i64<0>
-; CHECK:     t7: v16i8 = insert_subvector poison:v16i8, t5, Constant:i64<0>
+; CHECK:     t7: v16i8 = insert_subvector undef:v16i8, t5, Constant:i64<0>
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:v16i8 $q0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:v16i8 $q0, t9:1
 
@@ -69,7 +69,7 @@ define <vscale x 16 x i8> @insert_small_fixed_into_big_scalable(<8 x i8> %a) #0
 ; CHECK:           t2: nxv8i16,ch = CopyFromReg t0, Register:nxv8i16 %0
 ; CHECK:         t3: nxv8i8 = truncate t2
 ; CHECK:       t5: v4i8 = extract_subvector t3, Constant:i64<0>
-; CHECK:     t7: v16i8 = insert_subvector poison:v16i8, t5, Constant:i64<0>
+; CHECK:     t7: v16i8 = insert_subvector undef:v16i8, t5, Constant:i64<0>
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:v16i8 $q0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:v16i8 $q0, t9:1
 
@@ -86,7 +86,7 @@ define <16 x i8> @insert_small_scalable_into_big_fixed(<vscale x 8 x i8> %a) #0
 ; CHECK:           t2: nxv8i16,ch = CopyFromReg t0, Register:nxv8i16 %0
 ; CHECK:         t3: nxv8i8 = truncate t2
 ; CHECK:       t5: v4i8 = extract_subvector t3, Constant:i64<0>
-; CHECK:     t7: nxv16i8 = insert_subvector poison:nxv16i8, t5, Constant:i64<0>
+; CHECK:     t7: nxv16i8 = insert_subvector undef:nxv16i8, t5, Constant:i64<0>
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv16i8 $z0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv16i8 $z0, t9:1
 
@@ -95,7 +95,7 @@ define <16 x i8> @insert_small_scalable_into_big_fixed(<vscale x 8 x i8> %a) #0
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: nxv8i16,ch = CopyFromReg t0, Register:nxv8i16 %0
 ; CHECK:       t3: nxv8i8 = truncate t2
-; CHECK:     t11: nxv16i8 = insert_subvector poison:nxv16i8, t3, Constant:i64<0>
+; CHECK:     t11: nxv16i8 = insert_subvector undef:nxv16i8, t3, Constant:i64<0>
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv16i8 $z0, t11
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv16i8 $z0, t9:1
 
@@ -111,7 +111,7 @@ define <vscale x 16 x i8> @insert_small_scalable_into_big_scalable_1(<vscale x 8
 ; CHECK:           t2: nxv8i16,ch = CopyFromReg t0, Register:nxv8i16 %0
 ; CHECK:         t3: nxv8i8 = truncate t2
 ; CHECK:       t5: nxv4i8 = extract_subvector t3, Constant:i64<0>
-; CHECK:     t7: nxv16i8 = insert_subvector poison:nxv16i8, t5, Constant:i64<0>
+; CHECK:     t7: nxv16i8 = insert_subvector undef:nxv16i8, t5, Constant:i64<0>
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv16i8 $z0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv16i8 $z0, t9:1
 
@@ -120,7 +120,7 @@ define <vscale x 16 x i8> @insert_small_scalable_into_big_scalable_1(<vscale x 8
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: nxv8i16,ch = CopyFromReg t0, Register:nxv8i16 %0
 ; CHECK:       t3: nxv8i8 = truncate t2
-; CHECK:     t11: nxv16i8 = insert_subvector poison:nxv16i8, t3, Constant:i64<0>
+; CHECK:     t11: nxv16i8 = insert_subvector undef:nxv16i8, t3, Constant:i64<0>
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv16i8 $z0, t11
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv16i8 $z0, t9:1
 
@@ -135,7 +135,7 @@ define <vscale x 16 x i8> @insert_small_scalable_into_big_scalable_2(<vscale x 8
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: v16i8,ch = CopyFromReg t0, Register:v16i8 %0
 ; CHECK:       t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:     t6: v8i8 = insert_subvector poison:v8i8, t4, Constant:i64<0>
+; CHECK:     t6: v8i8 = insert_subvector undef:v8i8, t4, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:v8i8 $d0, t6
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:v8i8 $d0, t8:1
 
@@ -158,7 +158,7 @@ define <8 x i8> @extract_small_fixed_from_big_fixed(<16 x i8> %a) #0 {
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:           t2: v16i8,ch = CopyFromReg t0, Register:v16i8 %0
 ; CHECK:         t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:       t6: nxv8i8 = insert_subvector poison:nxv8i8, t4, Constant:i64<0>
+; CHECK:       t6: nxv8i8 = insert_subvector undef:nxv8i8, t4, Constant:i64<0>
 ; CHECK:     t7: nxv8i16 = any_extend t6
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv8i16 $z0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv8i16 $z0, t9:1
@@ -168,7 +168,7 @@ define <8 x i8> @extract_small_fixed_from_big_fixed(<16 x i8> %a) #0 {
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:           t2: v16i8,ch = CopyFromReg t0, Register:v16i8 %0
 ; CHECK:         t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:       t6: nxv8i8 = insert_subvector poison:nxv8i8, t4, Constant:i64<0>
+; CHECK:       t6: nxv8i8 = insert_subvector undef:nxv8i8, t4, Constant:i64<0>
 ; CHECK:     t7: nxv8i16 = any_extend t6
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv8i16 $z0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv8i16 $z0, t9:1
@@ -185,7 +185,7 @@ define <vscale x 8 x i8> @extract_small_scalable_from_big_fixed(<16 x i8> %a) #0
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: nxv16i8,ch = CopyFromReg t0, Register:nxv16i8 %0
 ; CHECK:       t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:     t6: v8i8 = insert_subvector poison:v8i8, t4, Constant:i64<0>
+; CHECK:     t6: v8i8 = insert_subvector undef:v8i8, t4, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:v8i8 $d0, t6
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:v8i8 $d0, t8:1
 
@@ -208,7 +208,7 @@ define <8 x i8> @extract_small_fixed_from_big_scalable(<vscale x 16 x i8> %a) #0
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:           t2: nxv16i8,ch = CopyFromReg t0, Register:nxv16i8 %0
 ; CHECK:         t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:       t6: nxv8i8 = insert_subvector poison:nxv8i8, t4, Constant:i64<0>
+; CHECK:       t6: nxv8i8 = insert_subvector undef:nxv8i8, t4, Constant:i64<0>
 ; CHECK:     t7: nxv8i16 = any_extend t6
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv8i16 $z0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv8i16 $z0, t9:1
@@ -233,7 +233,7 @@ define <vscale x 8 x i8> @extract_small_scalable_from_big_scalable_1(<vscale x 1
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:           t2: nxv16i8,ch = CopyFromReg t0, Register:nxv16i8 %0
 ; CHECK:         t4: nxv4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:       t6: nxv8i8 = insert_subvector poison:nxv8i8, t4, Constant:i64<0>
+; CHECK:       t6: nxv8i8 = insert_subvector undef:nxv8i8, t4, Constant:i64<0>
 ; CHECK:     t7: nxv8i16 = any_extend t6
 ; CHECK:   t9: ch,glue = CopyToReg t0, Register:nxv8i16 $z0, t7
 ; CHECK:   t10: ch = AArch64ISD::RET_GLUE t9, Register:nxv8i16 $z0, t9:1
@@ -258,7 +258,7 @@ define <vscale x 8 x i8> @extract_small_scalable_from_big_scalable_2(<vscale x 1
 ; CHECK:   t0: ch,glue = EntryToken
 ; CHECK:         t2: nxv16i8,ch = CopyFromReg t0, Register:nxv16i8 %0
 ; CHECK:       t4: v4i8 = extract_subvector t2, Constant:i64<0>
-; CHECK:     t6: v16i8 = insert_subvector poison:v16i8, t4, Constant:i64<0>
+; CHECK:     t6: v16i8 = insert_subvector undef:v16i8, t4, Constant:i64<0>
 ; CHECK:   t8: ch,glue = CopyToReg t0, Register:v16i8 $q0, t6
 ; CHECK:   t9: ch = AArch64ISD::RET_GLUE t8, Register:v16i8 $q0, t8:...
[truncated]

@kuhar kuhar merged commit ef1088f into main Apr 9, 2025
11 of 15 checks passed
@kuhar kuhar deleted the revert-125883-digger/ISD-POISON branch April 9, 2025 18:40
AllinLeeYL pushed a commit to AllinLeeYL/llvm-project that referenced this pull request Apr 10, 2025
@kuhar
Revert "[SelectionDAG] Introducing a new ISD::POISON SDNode to repres…
6df483c 
…ent the poison value in the IR." (llvm#135060)

Reverts llvm#125883

This PR causes crashes in RISC-V codegen around f16/f64 poison values:
llvm#125883 (comment)
var-const pushed a commit to ldionne/llvm-project that referenced this pull request Apr 17, 2025
@kuhar @var-const
Revert "[SelectionDAG] Introducing a new ISD::POISON SDNode to repres…
e7fa001 
…ent the poison value in the IR." (llvm#135060)

Reverts llvm#125883

This PR causes crashes in RISC-V codegen around f16/f64 poison values:
llvm#125883 (comment)
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@kuhar @llvmbot