CodeGen: Add ISD::AssertNoFPClass

[wzssyqa]

It is used to mark a value that we are sure that it is not some fcType.
The examples include:

• An arguments of a function is marked with nofpclass
• Output value of an intrinsic can be sure to not be some type

So that the following operation can make some assumptions.

[llvmbot]

@llvm/pr-subscribers-llvm-selectiondag

Author: YunQiang Su (wzssyqa)

Changes

It is used to mark a value that we are sure that it is not some fcType.
The examples include:

• An arguments of a function is marked with nofpclass
• Output value of an intrinsic can be sure to not be some type
  So that the following operation can make some assumptions.

---

Full diff: https://github.com/llvm/llvm-project/pull/135946.diff

7 Files Affected:

• (modified) llvm/include/llvm/CodeGen/ISDOpcodes.h (+6)
• (modified) llvm/include/llvm/Target/TargetSelectionDAG.td (+1)
• (modified) llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp (+3)
• (modified) llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp (+3)
• (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (+4)
• (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp (+1)
• (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (+1)

diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
index ad8a95a353b56..7a9b716f652f3 100644
--- a/llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -67,6 +67,12 @@ enum NodeType {
   /// poisoned the assertion will not be true for that value.
   AssertAlign,
 
+  /// AssertNoFPClass - These nodes record if a register contains a float
+  /// value that is known to be not some type.
+  /// NOTE: In case of the source value (or any vector element value) is
+  /// poisoned the assertion will not be true for that value.
+  AssertNoFPClass,
+
   /// Various leaf nodes.
   BasicBlock,
   VALUETYPE,
diff --git a/llvm/include/llvm/Target/TargetSelectionDAG.td b/llvm/include/llvm/Target/TargetSelectionDAG.td
index 9c241b6c4df0f..8453cf7f4e58a 100644
--- a/llvm/include/llvm/Target/TargetSelectionDAG.td
+++ b/llvm/include/llvm/Target/TargetSelectionDAG.td
@@ -859,6 +859,7 @@ def SDT_assert : SDTypeProfile<1, 1,
   [SDTCisInt<0>, SDTCisInt<1>, SDTCisSameAs<1, 0>]>;
 def assertsext : SDNode<"ISD::AssertSext", SDT_assert>;
 def assertzext : SDNode<"ISD::AssertZext", SDT_assert>;
+def assernofpclass : SDNode<"ISD::AssertNoFPClass", SDTFPUnaryOp>;
 def assertalign : SDNode<"ISD::AssertAlign", SDT_assert>;
 
 def convergencectrl_anchor : SDNode<"ISD::CONVERGENCECTRL_ANCHOR",
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
index 432209e8ecb0a..d03eeaa01b697 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
@@ -168,6 +168,7 @@ void DAGTypeLegalizer::SoftenFloatResult(SDNode *N, unsigned ResNo) {
     case ISD::POISON:
     case ISD::UNDEF:       R = SoftenFloatRes_UNDEF(N); break;
     case ISD::VAARG:       R = SoftenFloatRes_VAARG(N); break;
+    case ISD::AssertNoFPClass:       R = GetSoftenedFloat(N->getOperand(0)); break;
     case ISD::VECREDUCE_FADD:
     case ISD::VECREDUCE_FMUL:
     case ISD::VECREDUCE_FMIN:
@@ -2576,6 +2577,7 @@ bool DAGTypeLegalizer::PromoteFloatOperand(SDNode *N, unsigned OpNo) {
       R = PromoteFloatOp_FAKE_USE(N, OpNo);
       break;
     case ISD::FCOPYSIGN:  R = PromoteFloatOp_FCOPYSIGN(N, OpNo); break;
+    case ISD::AssertNoFPClass:
     case ISD::FP_TO_SINT:
     case ISD::FP_TO_UINT:
     case ISD::LROUND:
@@ -2803,6 +2805,7 @@ void DAGTypeLegalizer::PromoteFloatResult(SDNode *N, unsigned ResNo) {
     case ISD::FTRUNC:
     case ISD::FTAN:
     case ISD::FTANH:
+    case ISD::AssertNoFPClass:
     case ISD::FCANONICALIZE: R = PromoteFloatRes_UnaryOp(N); break;
 
     // Binary FP Operations
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index f934d8b37561e..d98d76b24bd7a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -129,6 +129,7 @@ void DAGTypeLegalizer::ScalarizeVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::UINT_TO_FP:
   case ISD::ZERO_EXTEND:
   case ISD::FCANONICALIZE:
+  case ISD::AssertNoFPClass:
     R = ScalarizeVecRes_UnaryOp(N);
     break;
   case ISD::ADDRSPACECAST:
@@ -1278,6 +1279,7 @@ void DAGTypeLegalizer::SplitVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::UINT_TO_FP:
   case ISD::VP_UINT_TO_FP:
   case ISD::FCANONICALIZE:
+  case ISD::AssertNoFPClass:
     SplitVecRes_UnaryOp(N, Lo, Hi);
     break;
   case ISD::ADDRSPACECAST:
@@ -4846,6 +4848,7 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::FREEZE:
   case ISD::ARITH_FENCE:
   case ISD::FCANONICALIZE:
+  case ISD::AssertNoFPClass:
     Res = WidenVecRes_Unary(N);
     break;
   case ISD::FMA: case ISD::VP_FMA:
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d6dcb3f15ae7c..9c821eabc4de3 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -7365,6 +7365,10 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
            N2.getOpcode() == ISD::TargetConstant && "Invalid FP_ROUND!");
     if (N1.getValueType() == VT) return N1;  // noop conversion.
     break;
+  case ISD::AssertNoFPClass:
+    assert(N1.getValueType().isFloatingPoint() &&
+           "AssertNoFPClass is used for a non-floating type");
+    return N1;
   case ISD::AssertSext:
   case ISD::AssertZext: {
     EVT EVT = cast<VTSDNode>(N2)->getVT();
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 8fcec6c6cd7c6..240115ac739f0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -122,6 +122,7 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   case ISD::TokenFactor:                return "TokenFactor";
   case ISD::AssertSext:                 return "AssertSext";
   case ISD::AssertZext:                 return "AssertZext";
+  case ISD::AssertNoFPClass:            return "AssertNoFPClass";
   case ISD::AssertAlign:                return "AssertAlign";
 
   case ISD::BasicBlock:                 return "BasicBlock";
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 598de6b207754..62d911fed2a3f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -3265,6 +3265,7 @@ void SelectionDAGISel::SelectCodeCommon(SDNode *NodeToMatch,
     return;
   case ISD::AssertSext:
   case ISD::AssertZext:
+  case ISD::AssertNoFPClass:
   case ISD::AssertAlign:
     ReplaceUses(SDValue(NodeToMatch, 0), NodeToMatch->getOperand(0));
     CurDAG->RemoveDeadNode(NodeToMatch);

[wzssyqa]

One example about how to use it: #130051

[arsenm]

This patch should include the wiring up to the argument lowering with tests

[arsenm]

Should include description of the operands, and the second one is a target constant with FPClassTest values

[arsenm]

Should assert the second operand is a valid FPClassTest