Add ISD::FROUND for libm round()

All libm floating-point rounding functions, except for round(), had their own
ISD nodes. Recent PowerPC cores have an instruction for round(), and so here I'm
adding ISD::FROUND so that round() can be custom lowered as well.

For the most part, this is straightforward. I've added an intrinsic
and a matching ISD node just like those for nearbyint() and friends. The
SelectionDAG pattern I've named frnd (because ISD::FP_ROUND has already claimed
fround).

This will be used by the PowerPC backend in a follow-up commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187926 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TargetLoweringBase.cpp b/lib/CodeGen/TargetLoweringBase.cpp
index 8d8f81b..c3afa77 100644
--- a/lib/CodeGen/TargetLoweringBase.cpp
+++ b/lib/CodeGen/TargetLoweringBase.cpp
@@ -191,6 +191,11 @@
   Names[RTLIB::NEARBYINT_F80] = "nearbyintl";
   Names[RTLIB::NEARBYINT_F128] = "nearbyintl";
   Names[RTLIB::NEARBYINT_PPCF128] = "nearbyintl";
+  Names[RTLIB::ROUND_F32] = "roundf";
+  Names[RTLIB::ROUND_F64] = "round";
+  Names[RTLIB::ROUND_F80] = "roundl";
+  Names[RTLIB::ROUND_F128] = "roundl";
+  Names[RTLIB::ROUND_PPCF128] = "roundl";
   Names[RTLIB::FLOOR_F32] = "floorf";
   Names[RTLIB::FLOOR_F64] = "floor";
   Names[RTLIB::FLOOR_F80] = "floorl";
@@ -706,6 +711,7 @@
   setOperationAction(ISD::FNEARBYINT, MVT::f16, Expand);
   setOperationAction(ISD::FCEIL,  MVT::f16, Expand);
   setOperationAction(ISD::FRINT,  MVT::f16, Expand);
+  setOperationAction(ISD::FROUND, MVT::f16, Expand);
   setOperationAction(ISD::FTRUNC, MVT::f16, Expand);
   setOperationAction(ISD::FLOG ,  MVT::f32, Expand);
   setOperationAction(ISD::FLOG2,  MVT::f32, Expand);
@@ -716,6 +722,7 @@
   setOperationAction(ISD::FNEARBYINT, MVT::f32, Expand);
   setOperationAction(ISD::FCEIL,  MVT::f32, Expand);
   setOperationAction(ISD::FRINT,  MVT::f32, Expand);
+  setOperationAction(ISD::FROUND, MVT::f32, Expand);
   setOperationAction(ISD::FTRUNC, MVT::f32, Expand);
   setOperationAction(ISD::FLOG ,  MVT::f64, Expand);
   setOperationAction(ISD::FLOG2,  MVT::f64, Expand);
@@ -726,6 +733,7 @@
   setOperationAction(ISD::FNEARBYINT, MVT::f64, Expand);
   setOperationAction(ISD::FCEIL,  MVT::f64, Expand);
   setOperationAction(ISD::FRINT,  MVT::f64, Expand);
+  setOperationAction(ISD::FROUND, MVT::f64, Expand);
   setOperationAction(ISD::FTRUNC, MVT::f64, Expand);
   setOperationAction(ISD::FLOG ,  MVT::f128, Expand);
   setOperationAction(ISD::FLOG2,  MVT::f128, Expand);
@@ -736,6 +744,7 @@
   setOperationAction(ISD::FNEARBYINT, MVT::f128, Expand);
   setOperationAction(ISD::FCEIL,  MVT::f128, Expand);
   setOperationAction(ISD::FRINT,  MVT::f128, Expand);
+  setOperationAction(ISD::FROUND, MVT::f128, Expand);
   setOperationAction(ISD::FTRUNC, MVT::f128, Expand);
 
   // Default ISD::TRAP to expand (which turns it into abort).