[ARMv8] Add CodeGen for VMAXNM/VMINNM.

llvm-svn: 189103

1 files changed, 16 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 7021941076f..74353c1788a 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1069,6 +1069,8 @@ const char *ARMTargetLowering::getTargetNodeName(unsigned Opcode) const {
   case ARMISD::BUILD_VECTOR:  return "ARMISD::BUILD_VECTOR";
   case ARMISD::FMAX:          return "ARMISD::FMAX";
   case ARMISD::FMIN:          return "ARMISD::FMIN";
+  case ARMISD::VMAXNM:        return "ARMISD::VMAX";
+  case ARMISD::VMINNM:        return "ARMISD::VMIN";
   case ARMISD::BFI:           return "ARMISD::BFI";
   case ARMISD::VORRIMM:       return "ARMISD::VORRIMM";
   case ARMISD::VBICIMM:       return "ARMISD::VBICIMM";
@@ -3276,6 +3278,20 @@ SDValue ARMTargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const {
   // Try to generate VSEL on ARMv8.
   if (getSubtarget()->hasV8FP() && (TrueVal.getValueType() == MVT::f32 ||
                                     TrueVal.getValueType() == MVT::f64)) {
+    // We can select VMAXNM/VMINNM from a compare followed by a select with the
+    // same operands, as follows:
+    //   c = fcmp [ogt, olt, ugt, ult] a, b
+    //   select c, a, b
+    // We only do this in unsafe-fp-math, because signed zeros and NaNs are
+    // handled differently than the original code sequence.
+    if (getTargetMachine().Options.UnsafeFPMath && LHS == TrueVal &&
+        RHS == FalseVal) {
+      if (CC == ISD::SETOGT || CC == ISD::SETUGT)
+        return DAG.getNode(ARMISD::VMAXNM, dl, VT, TrueVal, FalseVal);
+      if (CC == ISD::SETOLT || CC == ISD::SETULT)
+        return DAG.getNode(ARMISD::VMINNM, dl, VT, TrueVal, FalseVal);
+    }
+
     bool swpCmpOps = false;
     bool swpVselOps = false;
     checkVSELConstraints(CC, CondCode, swpCmpOps, swpVselOps);