[LegalizeTypes] Add SoftenFloatRes_FREEZE

[aqjune]

Summary

This adds SoftenFloatRes_FREEZE.

[aqjune]

I only have a test for SoftenFloatOp_FREEZE though; is there a good reference for writing a test for SoftenFloatRes_FREEZE?

[craig.topper]

llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

191

The type should come from TLI.getTypeToTransformTo

192

You should call GetSoftenedFloat on the operand.

805

Shouldn't the type of the input to freeze match the output so this shouldn't be needed.

[aqjune]

Address comments

[aqjune]

Thank you for the comments, I was trying to get more familiar with type legalization.
After the update, the test now calls SoftenFloatRes_FREEZE as well.

[craig.topper]

LGTM

llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

#endif
     case ISD::STRICT_FSUB:
     case ISD::FSUB:        R = SoftenFloatRes_FSUB(N); break;
     case ISD::STRICT_FTRUNC:
     case ISD::FTRUNC:      R = SoftenFloatRes_FTRUNC(N); break;
     case ISD::LOAD:        R = SoftenFloatRes_LOAD(N); break;
     case ISD::ATOMIC_SWAP: R = BitcastToInt_ATOMIC_SWAP(N); break;
     case ISD::SELECT:      R = SoftenFloatRes_SELECT(N); break;
     case ISD::SELECT_CC:   R = SoftenFloatRes_SELECT_CC(N); break;
+    case ISD::FREEZE:      R = SoftenFloatRes_FREEZE(N); break;
     case ISD::STRICT_SINT_TO_FP:
     case ISD::STRICT_UINT_TO_FP:
     case ISD::SINT_TO_FP:
     case ISD::UINT_TO_FP:  R = SoftenFloatRes_XINT_TO_FP(N); break;
     case ISD::UNDEF:       R = SoftenFloatRes_UNDEF(N); break;
     case ISD::VAARG:       R = SoftenFloatRes_VAARG(N); break;
   }
 
if (IsStrict)
     ReplaceValueWith(SDValue(N, 1), Tmp.second);
   return Tmp.first;
 }
 
 SDValue DAGTypeLegalizer::SoftenFloatRes_BITCAST(SDNode *N) {
   return BitConvertToInteger(N->getOperand(0));
 }
 
+SDValue DAGTypeLegalizer::SoftenFloatRes_FREEZE(SDNode *N) {
+  EVT Ty = TLI.getTypeToTransformTo(*DAG.getContext(), N->getValueType(0));
+  return DAG.getNode(ISD::FREEZE, SDLoc(N), Ty,
+                     GetSoftenedFloat(N->getOperand(0)));
+}
+
 SDValue DAGTypeLegalizer::SoftenFloatRes_MERGE_VALUES(SDNode *N,
                                                       unsigned ResNo) {
   SDValue Op = DisintegrateMERGE_VALUES(N, ResNo);
   return BitConvertToInteger(Op);
 }
 
 SDValue DAGTypeLegalizer::SoftenFloatRes_BUILD_PAIR(SDNode *N) {
   // Convert the inputs to integers, and build a new pair out of them.
#endif
   case ISD::STRICT_LLRINT:
   case ISD::LLRINT:      Res = SoftenFloatOp_LLRINT(N); break;
   case ISD::SELECT_CC:   Res = SoftenFloatOp_SELECT_CC(N); break;
   case ISD::STRICT_FSETCC:
   case ISD::STRICT_FSETCCS:
   case ISD::SETCC:       Res = SoftenFloatOp_SETCC(N); break;
   case ISD::STORE:       Res = SoftenFloatOp_STORE(N, OpNo); break;
   case ISD::FCOPYSIGN:   Res = SoftenFloatOp_FCOPYSIGN(N); break;
   }
 
   // If the result is null, the sub-method took care of registering results etc.
   if (!Res.getNode()) return false;
 
   // If the result is N, the sub-method updated N in place.  Tell the legalizer
   // core about this to re-analyze.
   if (Res.getNode() == N)
     return true;

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h

private:
   SDValue SoftenFloatRes_FMUL(SDNode *N);
   SDValue SoftenFloatRes_FNEARBYINT(SDNode *N);
   SDValue SoftenFloatRes_FNEG(SDNode *N);
   SDValue SoftenFloatRes_FP_EXTEND(SDNode *N);
   SDValue SoftenFloatRes_FP16_TO_FP(SDNode *N);
   SDValue SoftenFloatRes_FP_ROUND(SDNode *N);
   SDValue SoftenFloatRes_FPOW(SDNode *N);
   SDValue SoftenFloatRes_FPOWI(SDNode *N);
+  SDValue SoftenFloatRes_FREEZE(SDNode *N);
   SDValue SoftenFloatRes_FREM(SDNode *N);
   SDValue SoftenFloatRes_FRINT(SDNode *N);
   SDValue SoftenFloatRes_FROUND(SDNode *N);
   SDValue SoftenFloatRes_FSIN(SDNode *N);
   SDValue SoftenFloatRes_FSQRT(SDNode *N);
   SDValue SoftenFloatRes_FSUB(SDNode *N);
   SDValue SoftenFloatRes_FTRUNC(SDNode *N);
   SDValue SoftenFloatRes_LOAD(SDNode *N);

llvm/test/CodeGen/ARM/freeze-soften.ll

+; RUN: llc -mtriple=thumbv8m.main-none-eabi %s -o - | FileCheck %s
+
+; Check that freeze operations on floating types are successfully softened.
+
+; CHECK-LABEL: sitofp_f32_i32:
+; CHECK: bl __aeabi_i2f
+define float @sitofp_f32_i32(i32 %x) #0 {
+  %val = call float @llvm.experimental.constrained.sitofp.f32.i32(i32 %x, metadata !"round.tonearest", metadata !"fpexcept.strict") #0
+  %val.fr = freeze float %val
+  ret float %val.fr
+}
+
+attributes #0 = { strictfp }
+
+declare float @llvm.experimental.constrained.sitofp.f32.i32(i32, metadata, metadata)
+declare double @llvm.experimental.constrained.sitofp.f64.i32(i32, metadata, metadata)