Do not try to use i8 and i16 versions of FP_TO_INT soft float library calls

[mkuper]

Summary

It appears that neither compiler-rt nor the gnu soft-float libraries actually implement these conversions.

Instead of producing calls to library functions that don't exist, handle it similarly to the way we handle i8 -> float and i16 -> float conversions - call the i32 library function, and adjust the type.

[nadav]

LGTM.

include/llvm/CodeGen/RuntimeLibcalls.h

enum Libcall {
     FPROUND_PPCF128_F16,
     FPROUND_F64_F32,
     FPROUND_F80_F32,
     FPROUND_F128_F32,
     FPROUND_PPCF128_F32,
     FPROUND_F80_F64,
     FPROUND_F128_F64,
     FPROUND_PPCF128_F64,
-    FPTOSINT_F32_I8,
-    FPTOSINT_F32_I16,
     FPTOSINT_F32_I32,
     FPTOSINT_F32_I64,
     FPTOSINT_F32_I128,
-    FPTOSINT_F64_I8,
-    FPTOSINT_F64_I16,
     FPTOSINT_F64_I32,
     FPTOSINT_F64_I64,
     FPTOSINT_F64_I128,
     FPTOSINT_F80_I32,
     FPTOSINT_F80_I64,
     FPTOSINT_F80_I128,
     FPTOSINT_F128_I32,
     FPTOSINT_F128_I64,
     FPTOSINT_F128_I128,
     FPTOSINT_PPCF128_I32,
     FPTOSINT_PPCF128_I64,
     FPTOSINT_PPCF128_I128,
-    FPTOUINT_F32_I8,
-    FPTOUINT_F32_I16,
     FPTOUINT_F32_I32,
     FPTOUINT_F32_I64,
     FPTOUINT_F32_I128,
-    FPTOUINT_F64_I8,
-    FPTOUINT_F64_I16,
     FPTOUINT_F64_I32,
     FPTOUINT_F64_I64,
     FPTOUINT_F64_I128,
     FPTOUINT_F80_I32,
     FPTOUINT_F80_I64,
     FPTOUINT_F80_I128,
     FPTOUINT_F128_I32,
     FPTOUINT_F128_I64,

lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

 #endif
     llvm_unreachable("Do not know how to soften this operator's operand!");
 
   case ISD::BITCAST:     Res = SoftenFloatOp_BITCAST(N); break;
   case ISD::BR_CC:       Res = SoftenFloatOp_BR_CC(N); break;
   case ISD::FP_EXTEND:   Res = SoftenFloatOp_FP_EXTEND(N); break;
   case ISD::FP_TO_FP16:  // Same as FP_ROUND for softening purposes
   case ISD::FP_ROUND:    Res = SoftenFloatOp_FP_ROUND(N); break;
-  case ISD::FP_TO_SINT:  Res = SoftenFloatOp_FP_TO_SINT(N); break;
-  case ISD::FP_TO_UINT:  Res = SoftenFloatOp_FP_TO_UINT(N); break;
+  case ISD::FP_TO_SINT:
+  case ISD::FP_TO_UINT:  Res = SoftenFloatOp_FP_TO_XINT(N); break;
   case ISD::SELECT_CC:   Res = SoftenFloatOp_SELECT_CC(N); break;
   case ISD::SETCC:       Res = SoftenFloatOp_SETCC(N); break;
   case ISD::STORE:       Res = SoftenFloatOp_STORE(N, OpNo); break;
   }
 
   // If the result is null, the sub-method took care of registering results etc.
   if (!Res.getNode()) return false;
 
SDValue DAGTypeLegalizer::SoftenFloatOp_BR_CC(SDNode *N) {
 
   // Update N to have the operands specified.
   return SDValue(DAG.UpdateNodeOperands(N, N->getOperand(0),
                                 DAG.getCondCode(CCCode), NewLHS, NewRHS,
                                 N->getOperand(4)),
                  0);
 }
 
-SDValue DAGTypeLegalizer::SoftenFloatOp_FP_TO_SINT(SDNode *N) {
+SDValue DAGTypeLegalizer::SoftenFloatOp_FP_TO_XINT(SDNode *N) {
+  bool Signed = N->getOpcode() == ISD::FP_TO_SINT;
+  EVT SVT = N->getOperand(0).getValueType();
   EVT RVT = N->getValueType(0);
-  RTLIB::Libcall LC = RTLIB::getFPTOSINT(N->getOperand(0).getValueType(), RVT);
-  assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unsupported FP_TO_SINT!");
-  SDValue Op = GetSoftenedFloat(N->getOperand(0));
-  return TLI.makeLibCall(DAG, LC, RVT, Op, false, SDLoc(N)).first;
+  EVT NVT = EVT();
+  SDLoc dl(N);
+
+  // If the result is not legal, eg: fp -> i1, then it needs to be promoted to
+  // a larger type, eg: fp -> i32. Even if it is legal, no libcall may exactly
+  // match, eg. we don't have fp -> i8 conversions.
+  // Look for an appropriate libcall.
+  RTLIB::Libcall LC = RTLIB::UNKNOWN_LIBCALL;
+  for (unsigned IntVT = MVT::FIRST_INTEGER_VALUETYPE;
+       IntVT <= MVT::LAST_INTEGER_VALUETYPE && LC == RTLIB::UNKNOWN_LIBCALL;
+       ++IntVT) {
+    NVT = (MVT::SimpleValueType)IntVT;
+    // The type needs to big enough to hold the result.
+    if (NVT.bitsGE(RVT))
+      LC = Signed ? RTLIB::getFPTOSINT(SVT, NVT):RTLIB::getFPTOUINT(SVT, NVT);
   }
+  assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unsupported FP_TO_XINT!");
 
-SDValue DAGTypeLegalizer::SoftenFloatOp_FP_TO_UINT(SDNode *N) {
-  EVT RVT = N->getValueType(0);
-  RTLIB::Libcall LC = RTLIB::getFPTOUINT(N->getOperand(0).getValueType(), RVT);
-  assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unsupported FP_TO_UINT!");
   SDValue Op = GetSoftenedFloat(N->getOperand(0));
-  return TLI.makeLibCall(DAG, LC, RVT, Op, false, SDLoc(N)).first;
+  SDValue Res = TLI.makeLibCall(DAG, LC, NVT, Op, false, dl).first;
+
+  // Truncate the result if the libcall returns a larger type.
+  return DAG.getNode(ISD::TRUNCATE, dl, RVT, Res);
 }
 
 SDValue DAGTypeLegalizer::SoftenFloatOp_SELECT_CC(SDNode *N) {
   SDValue NewLHS = N->getOperand(0), NewRHS = N->getOperand(1);
   ISD::CondCode CCCode = cast<CondCodeSDNode>(N->getOperand(4))->get();
 
   EVT VT = NewLHS.getValueType();
   NewLHS = GetSoftenedFloat(NewLHS);

lib/CodeGen/SelectionDAG/LegalizeTypes.h

private:
   SDValue SoftenFloatRes_XINT_TO_FP(SDNode *N);
 
   // Operand Float to Integer Conversion.
   bool SoftenFloatOperand(SDNode *N, unsigned OpNo);
   SDValue SoftenFloatOp_BITCAST(SDNode *N);
   SDValue SoftenFloatOp_BR_CC(SDNode *N);
   SDValue SoftenFloatOp_FP_EXTEND(SDNode *N);
   SDValue SoftenFloatOp_FP_ROUND(SDNode *N);
-  SDValue SoftenFloatOp_FP_TO_SINT(SDNode *N);
-  SDValue SoftenFloatOp_FP_TO_UINT(SDNode *N);
+  SDValue SoftenFloatOp_FP_TO_XINT(SDNode *N);
   SDValue SoftenFloatOp_SELECT_CC(SDNode *N);
   SDValue SoftenFloatOp_SETCC(SDNode *N);
   SDValue SoftenFloatOp_STORE(SDNode *N, unsigned OpNo);
 
   //===--------------------------------------------------------------------===//
   // Float Expansion Support: LegalizeFloatTypes.cpp
   //===--------------------------------------------------------------------===//
 

lib/CodeGen/TargetLoweringBase.cpp

static void InitLibcallNames(const char **Names, const Triple &TT) {
   Names[RTLIB::FPROUND_PPCF128_F16] = "__trunctfhf2";
   Names[RTLIB::FPROUND_F64_F32] = "__truncdfsf2";
   Names[RTLIB::FPROUND_F80_F32] = "__truncxfsf2";
   Names[RTLIB::FPROUND_F128_F32] = "__trunctfsf2";
   Names[RTLIB::FPROUND_PPCF128_F32] = "__trunctfsf2";
   Names[RTLIB::FPROUND_F80_F64] = "__truncxfdf2";
   Names[RTLIB::FPROUND_F128_F64] = "__trunctfdf2";
   Names[RTLIB::FPROUND_PPCF128_F64] = "__trunctfdf2";
-  Names[RTLIB::FPTOSINT_F32_I8] = "__fixsfqi";
-  Names[RTLIB::FPTOSINT_F32_I16] = "__fixsfhi";
   Names[RTLIB::FPTOSINT_F32_I32] = "__fixsfsi";
   Names[RTLIB::FPTOSINT_F32_I64] = "__fixsfdi";
   Names[RTLIB::FPTOSINT_F32_I128] = "__fixsfti";
-  Names[RTLIB::FPTOSINT_F64_I8] = "__fixdfqi";
-  Names[RTLIB::FPTOSINT_F64_I16] = "__fixdfhi";
   Names[RTLIB::FPTOSINT_F64_I32] = "__fixdfsi";
   Names[RTLIB::FPTOSINT_F64_I64] = "__fixdfdi";
   Names[RTLIB::FPTOSINT_F64_I128] = "__fixdfti";
   Names[RTLIB::FPTOSINT_F80_I32] = "__fixxfsi";
   Names[RTLIB::FPTOSINT_F80_I64] = "__fixxfdi";
   Names[RTLIB::FPTOSINT_F80_I128] = "__fixxfti";
   Names[RTLIB::FPTOSINT_F128_I32] = "__fixtfsi";
   Names[RTLIB::FPTOSINT_F128_I64] = "__fixtfdi";
   Names[RTLIB::FPTOSINT_F128_I128] = "__fixtfti";
   Names[RTLIB::FPTOSINT_PPCF128_I32] = "__fixtfsi";
   Names[RTLIB::FPTOSINT_PPCF128_I64] = "__fixtfdi";
   Names[RTLIB::FPTOSINT_PPCF128_I128] = "__fixtfti";
-  Names[RTLIB::FPTOUINT_F32_I8] = "__fixunssfqi";
-  Names[RTLIB::FPTOUINT_F32_I16] = "__fixunssfhi";
   Names[RTLIB::FPTOUINT_F32_I32] = "__fixunssfsi";
   Names[RTLIB::FPTOUINT_F32_I64] = "__fixunssfdi";
   Names[RTLIB::FPTOUINT_F32_I128] = "__fixunssfti";
-  Names[RTLIB::FPTOUINT_F64_I8] = "__fixunsdfqi";
-  Names[RTLIB::FPTOUINT_F64_I16] = "__fixunsdfhi";
   Names[RTLIB::FPTOUINT_F64_I32] = "__fixunsdfsi";
   Names[RTLIB::FPTOUINT_F64_I64] = "__fixunsdfdi";
   Names[RTLIB::FPTOUINT_F64_I128] = "__fixunsdfti";
   Names[RTLIB::FPTOUINT_F80_I32] = "__fixunsxfsi";
   Names[RTLIB::FPTOUINT_F80_I64] = "__fixunsxfdi";
   Names[RTLIB::FPTOUINT_F80_I128] = "__fixunsxfti";
   Names[RTLIB::FPTOUINT_F128_I32] = "__fixunstfsi";
   Names[RTLIB::FPTOUINT_F128_I64] = "__fixunstfdi";
RTLIB::Libcall RTLIB::getFPROUND(EVT OpVT, EVT RetVT) {
 
   return UNKNOWN_LIBCALL;
 }
 
 /// getFPTOSINT - Return the FPTOSINT_*_* value for the given types, or
 /// UNKNOWN_LIBCALL if there is none.
 RTLIB::Libcall RTLIB::getFPTOSINT(EVT OpVT, EVT RetVT) {
   if (OpVT == MVT::f32) {
-    if (RetVT == MVT::i8)
-      return FPTOSINT_F32_I8;
-    if (RetVT == MVT::i16)
-      return FPTOSINT_F32_I16;
     if (RetVT == MVT::i32)
       return FPTOSINT_F32_I32;
     if (RetVT == MVT::i64)
       return FPTOSINT_F32_I64;
     if (RetVT == MVT::i128)
       return FPTOSINT_F32_I128;
   } else if (OpVT == MVT::f64) {
-    if (RetVT == MVT::i8)
-      return FPTOSINT_F64_I8;
-    if (RetVT == MVT::i16)
-      return FPTOSINT_F64_I16;
     if (RetVT == MVT::i32)
       return FPTOSINT_F64_I32;
     if (RetVT == MVT::i64)
       return FPTOSINT_F64_I64;
     if (RetVT == MVT::i128)
       return FPTOSINT_F64_I128;
   } else if (OpVT == MVT::f80) {
     if (RetVT == MVT::i32)
RTLIB::Libcall RTLIB::getFPTOSINT(EVT OpVT, EVT RetVT) {
   }
   return UNKNOWN_LIBCALL;
 }
 
 /// getFPTOUINT - Return the FPTOUINT_*_* value for the given types, or
 /// UNKNOWN_LIBCALL if there is none.
 RTLIB::Libcall RTLIB::getFPTOUINT(EVT OpVT, EVT RetVT) {
   if (OpVT == MVT::f32) {
-    if (RetVT == MVT::i8)
-      return FPTOUINT_F32_I8;
-    if (RetVT == MVT::i16)
-      return FPTOUINT_F32_I16;
     if (RetVT == MVT::i32)
       return FPTOUINT_F32_I32;
     if (RetVT == MVT::i64)
       return FPTOUINT_F32_I64;
     if (RetVT == MVT::i128)
       return FPTOUINT_F32_I128;
   } else if (OpVT == MVT::f64) {
-    if (RetVT == MVT::i8)
-      return FPTOUINT_F64_I8;
-    if (RetVT == MVT::i16)
-      return FPTOUINT_F64_I16;
     if (RetVT == MVT::i32)
       return FPTOUINT_F64_I32;
     if (RetVT == MVT::i64)
       return FPTOUINT_F64_I64;
     if (RetVT == MVT::i128)
       return FPTOUINT_F64_I128;
   } else if (OpVT == MVT::f80) {
     if (RetVT == MVT::i32)

test/CodeGen/X86/soft-sitofp.ll

 ; CHECK-LABEL: f_to_u32:
 ; CHECK: call{{l|q}} __fixunssfsi
 define i32 @f_to_u32(float %n) #0 {
 entry:
   %conv = fptoui float %n to i32
   ret i32 %conv
 }
 
+; CHECK-LABEL: f_to_s8:
+; CHECK: call{{l|q}} __fixsfsi
+define i8 @f_to_s8(float %f, i8 %i) #0 {
+entry:
+  %conv = fptosi float %f to i8
+  %add = add i8 %conv, %i
+  ret i8 %add
+}
+
+; CHECK-LABEL: f_to_u8:
+; CHECK: call{{l|q}} __fixunssfsi
+define i8 @f_to_u8(float %f, i8 %i) #0 {
+entry:
+  %conv = fptoui float %f to i8
+  %add = add i8 %conv, %i
+  ret i8 %add
+}
+
+; CHECK-LABEL: f_to_s16:
+; CHECK: call{{l|q}} __fixsfsi
+define i16 @f_to_s16(float %f, i16 %i) #0 {
+entry:
+  %conv = fptosi float %f to i16
+  %add = add i16 %conv, %i
+  ret i16 %add
+}
+
+; CHECK-LABEL: f_to_u16:
+; CHECK: call{{l|q}} __fixunssfsi
+define i16 @f_to_u16(float %f, i16 %i) #0 {
+entry:
+  %conv = fptoui float %f to i16
+  %add = add i16 %conv, %i
+  ret i16 %add
+}
+
 attributes #0 = { nounwind "use-soft-float"="true" }