Emit abs.s or abs.d only if -enable-no-nans-fp-math is supplied by user.

Invalid operation is signaled if the operand of these instructions is NaN.

llvm-svn: 154545

lib/Target/Mips/MipsISelLowering.cpp

@@ -147,6 +147,11 @@ MipsTargetLowering(MipsTargetMachine &TM)
   setOperationAction(ISD::MEMBARRIER,         MVT::Other, Custom);
   setOperationAction(ISD::ATOMIC_FENCE,       MVT::Other, 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);
@@ -734,6 +739,7 @@ LowerOperation(SDValue Op, SelectionDAG &DAG) const
     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::MEMBARRIER:         return LowerMEMBARRIER(Op, DAG);
     case ISD::ATOMIC_FENCE:       return LowerATOMIC_FENCE(Op, DAG);
@@ -1857,6 +1863,63 @@ MipsTargetLowering::LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const {
   return LowerFCOPYSIGN32(Op, DAG, Subtarget->hasMips32r2());
 }
 
+static SDValue LowerFABS32(SDValue Op, SelectionDAG &DAG, bool HasR2) {
+  SDValue Res, Const1 = DAG.getConstant(1, MVT::i32);
+  DebugLoc DL = Op.getDebugLoc();
+
+  // 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 (HasR2)
+    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 HasR2) {
+  SDValue Res, Const1 = DAG.getConstant(1, MVT::i32);
+  DebugLoc DL = Op.getDebugLoc();
+
+  // Bitcast to integer node.
+  SDValue X = DAG.getNode(ISD::BITCAST, DL, MVT::i64, Op.getOperand(0));
+
+  // Clear MSB.
+  if (HasR2)
+    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->hasMips32r2());
+
+  return LowerFABS32(Op, DAG, Subtarget->hasMips32r2());
+}
+
 SDValue MipsTargetLowering::
 LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const {
   // check the depth

lib/Target/Mips/MipsISelLowering.h

@@ -131,6 +131,7 @@ namespace llvm {
     SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerVASTART(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerFABS(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerMEMBARRIER(SDValue Op, SelectionDAG& DAG) const;
     SDValue LowerATOMIC_FENCE(SDValue Op, SelectionDAG& DAG) const;

lib/Target/Mips/MipsInstrFPU.td

@@ -190,6 +190,7 @@ let Predicates = [IsFP64bit] in {
  def CVT_D64_L : FFR1<0x21, 21, "cvt", "d.l", FGR64, FGR64>;
 }
 
+let Predicates = [NoNaNsFPMath] in
 defm FABS    : FFR1P_M<0x5, "abs",  fabs>;
 defm FNEG    : FFR1P_M<0x7, "neg",  fneg>;
 defm FSQRT   : FFR1P_M<0x4, "sqrt", fsqrt>;

test/CodeGen/Mips/fabs.ll

@@ -0,0 +1,52 @@
+; RUN: llc  < %s -march=mipsel -mcpu=mips32 | FileCheck %s -check-prefix=32
+; RUN: llc  < %s -march=mipsel -mcpu=mips32r2 | FileCheck %s -check-prefix=32R2
+; RUN: llc  < %s -march=mips64el -mcpu=mips64 -mattr=n64 | FileCheck %s -check-prefix=64
+; RUN: llc  < %s -march=mips64el -mcpu=mips64r2 -mattr=n64 | FileCheck %s -check-prefix=64R2
+; RUN: llc  < %s -march=mipsel -mcpu=mips32 -enable-no-nans-fp-math | FileCheck %s -check-prefix=NO-NAN
+
+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
+
+  %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
+
+  %call = tail call double @fabs(double %a) nounwind readnone
+  ret double %call
+}
+
+declare double @fabs(double) nounwind readnone