[mips] abs.[ds], and neg.[ds] should be allowed regardless of -enable-no-nans-fp-math

[dsanders]

Summary

They behave in accordance with the Has2008 and ABS2008 configuration bits of the
processor which are used to select between the 1985 and 2008 versions of IEEE

754. In 1985 mode, these instructions are arithmetic (i.e. they raise invalid

operation exceptions when given NaN), in 2008 mode they are non-arithmetic
(i.e. they are copies).

nmadd.[ds], and nmsub.[ds] are still subject to -enable-no-nans-fp-math because
the ISA spec does not explicitly state that they obey Has2008 and ABS2008.

[matheusalmeida]

LGTM.

test/CodeGen/Mips/fneg.ll

1

Shouldn't it be neg.[ds] ?

[dsanders]

test/CodeGen/Mips/fneg.ll

1

Well spotted. Thanks

lib/Target/Mips/MipsISelLowering.cpp

MipsTargetLowering::MipsTargetLowering(MipsTargetMachine &TM)
   setOperationAction(ISD::SETCC,              MVT::f32,   Custom);
   setOperationAction(ISD::SETCC,              MVT::f64,   Custom);
   setOperationAction(ISD::BRCOND,             MVT::Other, Custom);
   setOperationAction(ISD::VASTART,            MVT::Other, Custom);
   setOperationAction(ISD::FCOPYSIGN,          MVT::f32,   Custom);
   setOperationAction(ISD::FCOPYSIGN,          MVT::f64,   Custom);
   setOperationAction(ISD::FP_TO_SINT,         MVT::i32,   Custom);
 
-  if (!TM.Options.NoNaNsFPMath) {
-    setOperationAction(ISD::FABS,             MVT::f32,   Custom);
-    setOperationAction(ISD::FABS,             MVT::f64,   Custom);
-  }
-
   if (hasMips64()) {
     setOperationAction(ISD::GlobalAddress,      MVT::i64,   Custom);
     setOperationAction(ISD::BlockAddress,       MVT::i64,   Custom);
     setOperationAction(ISD::GlobalTLSAddress,   MVT::i64,   Custom);
     setOperationAction(ISD::JumpTable,          MVT::i64,   Custom);
     setOperationAction(ISD::ConstantPool,       MVT::i64,   Custom);
     setOperationAction(ISD::SELECT,             MVT::i64,   Custom);
     setOperationAction(ISD::LOAD,               MVT::i64,   Custom);
MipsTargetLowering::MipsTargetLowering(MipsTargetMachine &TM)
   setOperationAction(ISD::FLOG2,             MVT::f32,   Expand);
   setOperationAction(ISD::FLOG10,            MVT::f32,   Expand);
   setOperationAction(ISD::FEXP,              MVT::f32,   Expand);
   setOperationAction(ISD::FMA,               MVT::f32,   Expand);
   setOperationAction(ISD::FMA,               MVT::f64,   Expand);
   setOperationAction(ISD::FREM,              MVT::f32,   Expand);
   setOperationAction(ISD::FREM,              MVT::f64,   Expand);
 
-  if (!TM.Options.NoNaNsFPMath) {
-    setOperationAction(ISD::FNEG,             MVT::f32,   Expand);
-    setOperationAction(ISD::FNEG,             MVT::f64,   Expand);
-  }
-
   setOperationAction(ISD::EH_RETURN, MVT::Other, Custom);
 
   setOperationAction(ISD::VAARG,             MVT::Other, Expand);
   setOperationAction(ISD::VACOPY,            MVT::Other, Expand);
   setOperationAction(ISD::VAEND,             MVT::Other, Expand);
 
   // Use the default for now
   setOperationAction(ISD::STACKSAVE,         MVT::Other, Expand);
LowerOperation(SDValue Op, SelectionDAG &DAG) const
   case ISD::BlockAddress:       return lowerBlockAddress(Op, DAG);
   case ISD::GlobalTLSAddress:   return lowerGlobalTLSAddress(Op, DAG);
   case ISD::JumpTable:          return lowerJumpTable(Op, DAG);
   case ISD::SELECT:             return lowerSELECT(Op, DAG);
   case ISD::SELECT_CC:          return lowerSELECT_CC(Op, DAG);
   case ISD::SETCC:              return lowerSETCC(Op, DAG);
   case ISD::VASTART:            return lowerVASTART(Op, DAG);
   case ISD::FCOPYSIGN:          return lowerFCOPYSIGN(Op, DAG);
-  case ISD::FABS:               return lowerFABS(Op, DAG);
   case ISD::FRAMEADDR:          return lowerFRAMEADDR(Op, DAG);
   case ISD::RETURNADDR:         return lowerRETURNADDR(Op, DAG);
   case ISD::EH_RETURN:          return lowerEH_RETURN(Op, DAG);
   case ISD::ATOMIC_FENCE:       return lowerATOMIC_FENCE(Op, DAG);
   case ISD::SHL_PARTS:          return lowerShiftLeftParts(Op, DAG);
   case ISD::SRA_PARTS:          return lowerShiftRightParts(Op, DAG, true);
   case ISD::SRL_PARTS:          return lowerShiftRightParts(Op, DAG, false);
   case ISD::LOAD:               return lowerLOAD(Op, DAG);

 SDValue
 MipsTargetLowering::lowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const {
   if (Subtarget->hasMips64())
     return lowerFCOPYSIGN64(Op, DAG, Subtarget->hasExtractInsert());
 
   return lowerFCOPYSIGN32(Op, DAG, Subtarget->hasExtractInsert());
 }
 
-static SDValue lowerFABS32(SDValue Op, SelectionDAG &DAG,
-                           bool HasExtractInsert) {
-  SDValue Res, Const1 = DAG.getConstant(1, MVT::i32);
-  SDLoc DL(Op);
-
-  // If operand is of type f64, extract the upper 32-bit. Otherwise, bitcast it
-  // to i32.
-  SDValue X = (Op.getValueType() == MVT::f32) ?
-    DAG.getNode(ISD::BITCAST, DL, MVT::i32, Op.getOperand(0)) :
-    DAG.getNode(MipsISD::ExtractElementF64, DL, MVT::i32, Op.getOperand(0),
-                Const1);
-
-  // Clear MSB.
-  if (HasExtractInsert)
-    Res = DAG.getNode(MipsISD::Ins, DL, MVT::i32,
-                      DAG.getRegister(Mips::ZERO, MVT::i32),
-                      DAG.getConstant(31, MVT::i32), Const1, X);
-  else {
-    SDValue SllX = DAG.getNode(ISD::SHL, DL, MVT::i32, X, Const1);
-    Res = DAG.getNode(ISD::SRL, DL, MVT::i32, SllX, Const1);
-  }
-
-  if (Op.getValueType() == MVT::f32)
-    return DAG.getNode(ISD::BITCAST, DL, MVT::f32, Res);
-
-  SDValue LowX = DAG.getNode(MipsISD::ExtractElementF64, DL, MVT::i32,
-                             Op.getOperand(0), DAG.getConstant(0, MVT::i32));
-  return DAG.getNode(MipsISD::BuildPairF64, DL, MVT::f64, LowX, Res);
-}
-
-static SDValue lowerFABS64(SDValue Op, SelectionDAG &DAG,
-                           bool HasExtractInsert) {
-  SDValue Res, Const1 = DAG.getConstant(1, MVT::i32);
-  SDLoc DL(Op);
-
-  // Bitcast to integer node.
-  SDValue X = DAG.getNode(ISD::BITCAST, DL, MVT::i64, Op.getOperand(0));
-
-  // Clear MSB.
-  if (HasExtractInsert)
-    Res = DAG.getNode(MipsISD::Ins, DL, MVT::i64,
-                      DAG.getRegister(Mips::ZERO_64, MVT::i64),
-                      DAG.getConstant(63, MVT::i32), Const1, X);
-  else {
-    SDValue SllX = DAG.getNode(ISD::SHL, DL, MVT::i64, X, Const1);
-    Res = DAG.getNode(ISD::SRL, DL, MVT::i64, SllX, Const1);
-  }
-
-  return DAG.getNode(ISD::BITCAST, DL, MVT::f64, Res);
-}
-
-SDValue
-MipsTargetLowering::lowerFABS(SDValue Op, SelectionDAG &DAG) const {
-  if (Subtarget->hasMips64() && (Op.getValueType() == MVT::f64))
-    return lowerFABS64(Op, DAG, Subtarget->hasExtractInsert());
-
-  return lowerFABS32(Op, DAG, Subtarget->hasExtractInsert());
-}
-
 SDValue MipsTargetLowering::
 lowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const {
   // check the depth
   assert((cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue() == 0) &&
          "Frame address can only be determined for current frame.");
 
   MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
   MFI->setFrameAddressIsTaken(true);

lib/Target/Mips/MipsInstrFPU.td

 let isPseudo = 1, isCodeGenOnly = 1 in {
   def PseudoCVT_S_W : ABSS_FT<"", FGR32Opnd, GPR32Opnd, II_CVT>;
   def PseudoCVT_D32_W : ABSS_FT<"", AFGR64Opnd, GPR32Opnd, II_CVT>;
   def PseudoCVT_S_L : ABSS_FT<"", FGR64Opnd, GPR64Opnd, II_CVT>;
   def PseudoCVT_D64_W : ABSS_FT<"", FGR64Opnd, GPR32Opnd, II_CVT>;
   def PseudoCVT_D64_L : ABSS_FT<"", FGR64Opnd, GPR64Opnd, II_CVT>;
 }
 
-let Predicates = [NoNaNsFPMath, HasStdEnc] in {
+let Predicates = [HasStdEnc] in {
   def FABS_S : MMRel, ABSS_FT<"abs.s", FGR32Opnd, FGR32Opnd, II_ABS, fabs>,
                ABSS_FM<0x5, 16>;
   def FNEG_S : MMRel, ABSS_FT<"neg.s", FGR32Opnd, FGR32Opnd, II_NEG, fneg>,
                ABSS_FM<0x7, 16>;
   defm FABS : ABSS_M<"abs.d", II_ABS, fabs>, ABSS_FM<0x5, 17>;
   defm FNEG : ABSS_M<"neg.d", II_NEG, fneg>, ABSS_FM<0x7, 17>;
 }
 

lib/Target/Mips/MipsInstrInfo.td

 def InMips16Mode :    Predicate<"Subtarget.inMips16Mode()">,
                       AssemblerPredicate<"FeatureMips16">;
 def HasCnMips    :    Predicate<"Subtarget.hasCnMips()">,
                       AssemblerPredicate<"FeatureCnMips">;
 def RelocStatic :     Predicate<"TM.getRelocationModel() == Reloc::Static">,
                       AssemblerPredicate<"FeatureMips32">;
 def RelocPIC    :     Predicate<"TM.getRelocationModel() == Reloc::PIC_">,
                       AssemblerPredicate<"FeatureMips32">;
-def NoNaNsFPMath :    Predicate<"TM.Options.NoNaNsFPMath">,
-                      AssemblerPredicate<"FeatureMips32">;
+def NoNaNsFPMath :    Predicate<"TM.Options.NoNaNsFPMath">;
 def HasStdEnc :       Predicate<"Subtarget.hasStandardEncoding()">,
                       AssemblerPredicate<"!FeatureMips16">;
 def NotDSP :          Predicate<"!Subtarget.hasDSP()">;
 def InMicroMips    :  Predicate<"Subtarget.inMicroMipsMode()">,
                       AssemblerPredicate<"FeatureMicroMips">;
 def NotInMicroMips :  Predicate<"!Subtarget.inMicroMipsMode()">,
                       AssemblerPredicate<"!FeatureMicroMips">;
 def IsLE           :  Predicate<"Subtarget.isLittle()">;

test/CodeGen/Mips/fabs.ll

-; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32 | FileCheck %s -check-prefix=32
-; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32r2 | FileCheck %s -check-prefix=32R2
-; RUN: llc  < %s -mtriple=mips64el-linux-gnu -mcpu=mips64 -mattr=n64 | FileCheck %s -check-prefix=64
-; RUN: llc  < %s -mtriple=mips64el-linux-gnu -mcpu=mips64r2 -mattr=n64 | FileCheck %s -check-prefix=64R2
-; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32 -enable-no-nans-fp-math | FileCheck %s -check-prefix=NO-NAN
+; Check that abs.[ds] is selected and does not depend on -enable-no-nans-fp-math
+; They obey the Has2008 and ABS2008 configuration bits which govern the
+; conformance to IEEE 754 (1985) and IEEE 754 (2008). When these bits are not
+; present, they confirm to 1985.
+; In 1985 mode, abs.[ds] are arithmetic (i.e. they raise invalid operation
+; exceptions when given NaN's). In 2008 mode, they are non-arithmetic (i.e.
+; they are copies and don't raise any exceptions).
+
+; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32 | FileCheck %s
+; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32r2 | FileCheck %s
+; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32 -enable-no-nans-fp-math | FileCheck %s
 
 define float @foo0(float %a) nounwind readnone {
 entry:
 
-; 32: lui  $[[T0:[0-9]+]], 32767
-; 32: ori  $[[MSK0:[0-9]+]], $[[T0]], 65535
-; 32: and  $[[AND:[0-9]+]], ${{[0-9]+}}, $[[MSK0]]
-; 32: mtc1 $[[AND]], $f0
-
-; 32R2: ins  $[[INS:[0-9]+]], $zero, 31, 1
-; 32R2: mtc1 $[[INS]], $f0
-
-; NO-NAN: abs.s
+; CHECK-LABEL: foo0
+; CHECK: abs.s
 
   %call = tail call float @fabsf(float %a) nounwind readnone
   ret float %call
 }
 
 declare float @fabsf(float) nounwind readnone
 
 define double @foo1(double %a) nounwind readnone {
 entry:
 
-; 32: lui  $[[T0:[0-9]+]], 32767
-; 32: ori  $[[MSK0:[0-9]+]], $[[T0]], 65535
-; 32: and  $[[AND:[0-9]+]], ${{[0-9]+}}, $[[MSK0]]
-; 32: mtc1 $[[AND]], $f1
-
-; 32R2: ins  $[[INS:[0-9]+]], $zero, 31, 1
-; 32R2: mtc1 $[[INS]], $f1
-
-; 64: daddiu  $[[T0:[0-9]+]], $zero, 1
-; 64: dsll    $[[T1:[0-9]+]], ${{[0-9]+}}, 63
-; 64: daddiu  $[[MSK0:[0-9]+]], $[[T1]], -1
-; 64: and     $[[AND:[0-9]+]], ${{[0-9]+}}, $[[MSK0]]
-; 64: dmtc1   $[[AND]], $f0
-
-; 64R2: dins  $[[INS:[0-9]+]], $zero, 63, 1
-; 64R2: dmtc1 $[[INS]], $f0
-
-; NO-NAN: abs.d
+; CHECK-LABEL: foo1:
+; CHECK: abs.d
 
   %call = tail call double @fabs(double %a) nounwind readnone
   ret double %call
 }
 
 declare double @fabs(double) nounwind readnone

test/CodeGen/Mips/fmadd1.ll

+; Check that madd.[ds], msub.[ds], nmadd.[ds], and nmsub.[ds] are supported
+; correctly.
+; The spec for nmadd.[ds], and nmsub.[ds] does not state that they obey the
+; the Has2008 and ABS2008 configuration bits which govern the conformance to
+; IEEE 754 (1985) and IEEE 754 (2008). These instructions are therefore only
+; available when -enable-no-nans-fp-math is given.
+
 ; RUN: llc < %s -march=mipsel -mcpu=mips32r2 -enable-no-nans-fp-math | FileCheck %s -check-prefix=32R2 -check-prefix=CHECK
 ; RUN: llc < %s -march=mips64el -mcpu=mips64r2 -mattr=n64 -enable-no-nans-fp-math | FileCheck %s -check-prefix=64R2 -check-prefix=CHECK
 ; RUN: llc < %s -march=mipsel -mcpu=mips32r2 | FileCheck %s -check-prefix=32R2NAN -check-prefix=CHECK
 ; RUN: llc < %s -march=mips64el -mcpu=mips64r2 -mattr=n64 | FileCheck %s -check-prefix=64R2NAN -check-prefix=CHECK
 
 define float @FOO0float(float %a, float %b, float %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO0float:
 ; CHECK: madd.s 
   %mul = fmul float %a, %b
   %add = fadd float %mul, %c
   %add1 = fadd float %add, 0.000000e+00
   ret float %add1
 }
 
 define float @FOO1float(float %a, float %b, float %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO1float:
 ; CHECK: msub.s 
   %mul = fmul float %a, %b
   %sub = fsub float %mul, %c
   %add = fadd float %sub, 0.000000e+00
   ret float %add
 }
 
 define float @FOO2float(float %a, float %b, float %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO2float:
 ; 32R2: nmadd.s 
 ; 64R2: nmadd.s 
 ; 32R2NAN: madd.s 
 ; 64R2NAN: madd.s 
   %mul = fmul float %a, %b
   %add = fadd float %mul, %c
   %sub = fsub float 0.000000e+00, %add
   ret float %sub
 }
 
 define float @FOO3float(float %a, float %b, float %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO3float:
 ; 32R2: nmsub.s 
 ; 64R2: nmsub.s 
 ; 32R2NAN: msub.s 
 ; 64R2NAN: msub.s 
   %mul = fmul float %a, %b
   %sub = fsub float %mul, %c
   %sub1 = fsub float 0.000000e+00, %sub
   ret float %sub1
 }
 
 define double @FOO10double(double %a, double %b, double %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO10double:
 ; CHECK: madd.d
   %mul = fmul double %a, %b
   %add = fadd double %mul, %c
   %add1 = fadd double %add, 0.000000e+00
   ret double %add1
 }
 
 define double @FOO11double(double %a, double %b, double %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO11double:
 ; CHECK: msub.d
   %mul = fmul double %a, %b
   %sub = fsub double %mul, %c
   %add = fadd double %sub, 0.000000e+00
   ret double %add
 }
 
 define double @FOO12double(double %a, double %b, double %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO12double:
 ; 32R2: nmadd.d 
 ; 64R2: nmadd.d 
 ; 32R2NAN: madd.d 
 ; 64R2NAN: madd.d 
   %mul = fmul double %a, %b
   %add = fadd double %mul, %c
   %sub = fsub double 0.000000e+00, %add
   ret double %sub
 }
 
 define double @FOO13double(double %a, double %b, double %c) nounwind readnone {
 entry:
+; CHECK-LABEL: FOO13double:
 ; 32R2: nmsub.d 
 ; 64R2: nmsub.d 
 ; 32R2NAN: msub.d 
 ; 64R2NAN: msub.d 
   %mul = fmul double %a, %b
   %sub = fsub double %mul, %c
   %sub1 = fsub double 0.000000e+00, %sub
   ret double %sub1
 }

test/CodeGen/Mips/fneg.ll

-; RUN: llc  < %s -march=mipsel -mcpu=mips32 | FileCheck %s 
+; Check that abs.[ds] is selected and does not depend on -enable-no-nans-fp-math
+; They obey the Has2008 and ABS2008 configuration bits which govern the
+; conformance to IEEE 754 (1985) and IEEE 754 (2008). When these bits are not
+; present, they confirm to 1985.
+; In 1985 mode, abs.[ds] are arithmetic (i.e. they raise invalid operation
+; exceptions when given NaN's). In 2008 mode, they are non-arithmetic (i.e.
+; they are copies and don't raise any exceptions).
 
-define float @foo0(i32 %a, float %d) nounwind readnone {
+; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32 | FileCheck %s
+; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32r2 | FileCheck %s
+; RUN: llc  < %s -mtriple=mipsel-linux-gnu -mcpu=mips32 -enable-no-nans-fp-math | FileCheck %s
+
+define float @foo0(float %d) nounwind readnone {
 entry:
-; CHECK-NOT: neg.s
+; CHECK-LABEL: foo0:
+; CHECK: neg.s
   %sub = fsub float -0.000000e+00, %d
   ret float %sub
 }
 
-define double @foo1(i32 %a, double %d) nounwind readnone {
+define double @foo1(double %d) nounwind readnone {
 entry:
-; CHECK:     foo1
-; CHECK-NOT: neg.d
-; CHECK:     jr
+; CHECK-LABEL: foo1:
+; CHECK: neg.d
   %sub = fsub double -0.000000e+00, %d
   ret double %sub
 }