Mark FP_ROUND for converting NEON v2f64 to v2f32 as expand. Add a missing

case to vector legalization so this actually works.

Patch by Pete Couperus.  Fixes PR12540.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168107 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp

@@ -221,6 +221,7 @@ SDValue VectorLegalizer::LegalizeOp(SDValue Op) {
   case ISD::FRINT:
   case ISD::FNEARBYINT:
   case ISD::FFLOOR:
+  case ISD::FP_ROUND:
   case ISD::FMA:
   case ISD::SIGN_EXTEND_INREG:
     QueryType = Node->getValueType(0);

lib/Target/ARM/ARMISelLowering.cpp

@@ -544,6 +544,8 @@ ARMTargetLowering::ARMTargetLowering(TargetMachine &TM)
     setOperationAction(ISD::FP_TO_UINT, MVT::v4i16, Custom);
     setOperationAction(ISD::FP_TO_SINT, MVT::v4i16, Custom);
 
+    setOperationAction(ISD::FP_ROUND,   MVT::v2f32, Expand);
+
     setTargetDAGCombine(ISD::INTRINSIC_VOID);
     setTargetDAGCombine(ISD::INTRINSIC_W_CHAIN);
     setTargetDAGCombine(ISD::INTRINSIC_WO_CHAIN);

test/CodeGen/ARM/neon_fpconv.ll

@@ -0,0 +1,9 @@
+; RUN: llc < %s -march=arm -mattr=+neon | FileCheck %s
+
+; PR12540: ARM backend lowering of FP_ROUND v2f64 to v2f32.
+define <2 x float> @vtrunc(<2 x double> %a) {
+; CHECK: vcvt.f32.f64 [[S0:s[0-9]+]], [[D0:d[0-9]+]]
+; CHECK: vcvt.f32.f64 [[S1:s[0-9]+]], [[D1:d[0-9]+]]
+  %vt = fptrunc <2 x double> %a to <2 x float>
+  ret <2 x float> %vt
+}