[llvm] [SelectionDAG][RISCV] Operations with static rounding (PR #100999)

[Matt Arsenault via llvm-commits]

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@@ -8131,15 +8131,73 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
 void SelectionDAGBuilder::visitConstrainedFPIntrinsic(
     const ConstrainedFPIntrinsic &FPI) {
   SDLoc sdl = getCurSDLoc();
+  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+  EVT VT = TLI.getValueType(DAG.getDataLayout(), FPI.getType());
+  fp::ExceptionBehavior EB = *FPI.getExceptionBehavior();
+  std::optional<RoundingMode> RM = FPI.getRoundingMode();
+
+  SDNodeFlags Flags;
+  if (EB == fp::ExceptionBehavior::ebIgnore)
+    Flags.setNoFPExcept(true);
+
+  if (auto *FPOp = dyn_cast<FPMathOperator>(&FPI))
+    Flags.copyFMF(*FPOp);
+
+  bool UseStaticRounding = EB == fp::ExceptionBehavior::ebIgnore && RM &&
+                           *RM != RoundingMode::Dynamic &&
+                           TLI.isStaticRoundingSupportedFor(FPI);
+  unsigned Opcode = 0;
+  SmallVector<SDValue, 4> Opers;
+  for (unsigned I = 0, E = FPI.getNonMetadataArgCount(); I != E; ++I)
+    Opers.push_back(getValue(FPI.getArgOperand(I)));
+
+  if (UseStaticRounding) {
+    switch (FPI.getIntrinsicID()) {
+    case Intrinsic::experimental_constrained_fadd:
+      Opcode = ISD::FADD_MODE;
+      break;
+    case Intrinsic::experimental_constrained_fsub:
+      Opcode = ISD::FSUB_MODE;
+      break;
+    case Intrinsic::experimental_constrained_fmul:
+      Opcode = ISD::FMUL_MODE;
+      break;
+    case Intrinsic::experimental_constrained_fdiv:
+      Opcode = ISD::FDIV_MODE;
+      break;
+    case Intrinsic::experimental_constrained_sqrt:
+      Opcode = ISD::FSQRT_MODE;
+      break;
+    case Intrinsic::experimental_constrained_fma:
+      Opcode = ISD::FMA_MODE;
+      break;
+    case Intrinsic::experimental_constrained_sitofp:
+      Opcode = ISD::SINT_TO_FP_MODE;
+      break;
+    case Intrinsic::experimental_constrained_uitofp:
+      Opcode = ISD::UINT_TO_FP_MODE;
+      break;
+    case Intrinsic::experimental_constrained_fptrunc:
+      Opcode = ISD::FP_ROUND_MODE;
+      break;
+    }
+    if (Opcode) {
+      int MachineRM = TLI.getMachineRoundingMode(*RM);
+      assert(MachineRM >= 0 && "Unsupported rounding mode");
+      EVT RMType = TLI.getTypeToTransformTo(*DAG.getContext(), MVT::i32);
+      Opers.push_back(DAG.getConstant(static_cast<uint64_t>(MachineRM), sdl,
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arsenm wrote:

getTargetConstant 

https://github.com/llvm/llvm-project/pull/100999