Vector fneg must be expanded into fsub -0.0, X.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40586 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 21 insertions, 2 deletions

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 0ed1112fff..6f4d923cff 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -259,6 +259,7 @@ PPCTargetLowering::PPCTargetLowering(PPCTargetMachine &TM)
       setOperationAction(ISD::UDIV, (MVT::ValueType)VT, Expand);
       setOperationAction(ISD::UREM, (MVT::ValueType)VT, Expand);
       setOperationAction(ISD::FDIV, (MVT::ValueType)VT, Expand);
+      setOperationAction(ISD::FNEG, (MVT::ValueType)VT, Expand);
       setOperationAction(ISD::EXTRACT_VECTOR_ELT, (MVT::ValueType)VT, Expand);
       setOperationAction(ISD::INSERT_VECTOR_ELT, (MVT::ValueType)VT, Expand);
       setOperationAction(ISD::BUILD_VECTOR, (MVT::ValueType)VT, Expand);
@@ -523,6 +524,16 @@ bool PPC::isSplatShuffleMask(SDNode *N, unsigned EltSize) {
   return true;
 }
 
+/// isAllNegativeZeroVector - Returns true if all elements of build_vector
+/// are -0.0.
+bool PPC::isAllNegativeZeroVector(SDNode *N) {
+  assert(N->getOpcode() == ISD::BUILD_VECTOR);
+  if (PPC::isSplatShuffleMask(N, N->getNumOperands()))
+    if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N))
+      return CFP->isExactlyValue(-0.0);
+  return false;
+}
+
 /// getVSPLTImmediate - Return the appropriate VSPLT* immediate to splat the
 /// specified isSplatShuffleMask VECTOR_SHUFFLE mask.
 unsigned PPC::getVSPLTImmediate(SDNode *N, unsigned EltSize) {
diff --git a/lib/Target/PowerPC/PPCISelLowering.h b/lib/Target/PowerPC/PPCISelLowering.h
index 05818652b6..245fe53e5a 100644
--- a/lib/Target/PowerPC/PPCISelLowering.h
+++ b/lib/Target/PowerPC/PPCISelLowering.h
@@ -160,6 +160,10 @@ namespace llvm {
     /// VSPLTB/VSPLTH/VSPLTW.
     bool isSplatShuffleMask(SDNode *N, unsigned EltSize);
     
+    /// isAllNegativeZeroVector - Returns true if all elements of build_vector
+    /// are -0.0.
+    bool isAllNegativeZeroVector(SDNode *N);
+
     /// getVSPLTImmediate - Return the appropriate VSPLT* immediate to splat the
     /// specified isSplatShuffleMask VECTOR_SHUFFLE mask.
     unsigned getVSPLTImmediate(SDNode *N, unsigned EltSize);
diff --git a/lib/Target/PowerPC/PPCInstrAltivec.td b/lib/Target/PowerPC/PPCInstrAltivec.td
index 572be98825..7a404adee6 100644
--- a/lib/Target/PowerPC/PPCInstrAltivec.td
+++ b/lib/Target/PowerPC/PPCInstrAltivec.td
@@ -70,7 +70,6 @@ def VMRGHW_unary_shuffle_mask : PatLeaf<(build_vector), [{
   return PPC::isVMRGHShuffleMask(N, 4, true);
 }]>;
 
-
 def VSLDOI_get_imm : SDNodeXForm<build_vector, [{
   return getI32Imm(PPC::isVSLDOIShuffleMask(N, false));
 }]>;
@@ -133,6 +132,10 @@ def vecspltisw : PatLeaf<(build_vector), [{
   return PPC::get_VSPLTI_elt(N, 4, *CurDAG).Val != 0;
 }], VSPLTISW_get_imm>;
 
+def V_immneg0 : PatLeaf<(build_vector), [{
+  return PPC::isAllNegativeZeroVector(N);
+}]>;
+
 //===----------------------------------------------------------------------===//
 // Helpers for defining instructions that directly correspond to intrinsics.
 
@@ -228,7 +231,8 @@ def VMADDFP : VAForm_1<46, (outs VRRC:$vD), (ins VRRC:$vA, VRRC:$vC, VRRC:$vB),
                        Requires<[FPContractions]>;
 def VNMSUBFP: VAForm_1<47, (outs VRRC:$vD), (ins VRRC:$vA, VRRC:$vC, VRRC:$vB),
                        "vnmsubfp $vD, $vA, $vC, $vB", VecFP,
-                       [(set VRRC:$vD, (fneg (fsub (fmul VRRC:$vA, VRRC:$vC),
+                       [(set VRRC:$vD, (fsub V_immneg0,
+                                             (fsub (fmul VRRC:$vA, VRRC:$vC),
                                                    VRRC:$vB)))]>,
                        Requires<[FPContractions]>;