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

1 files changed, 36 insertions, 0 deletions

diff --git a/docs/LangRef.rst b/docs/LangRef.rst
index b69e2a35d1..5b8ecd85c6 100644
--- a/docs/LangRef.rst
+++ b/docs/LangRef.rst
@@ -7526,6 +7526,42 @@ Semantics:
 This function returns the same values as the libm ``nearbyint``
 functions would, and handles error conditions in the same way.
 
+'``llvm.round.*``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+This is an overloaded intrinsic. You can use ``llvm.round`` on any
+floating point or vector of floating point type. Not all targets support
+all types however.
+
+::
+
+      declare float     @llvm.round.f32(float  %Val)
+      declare double    @llvm.round.f64(double %Val)
+      declare x86_fp80  @llvm.round.f80(x86_fp80  %Val)
+      declare fp128     @llvm.round.f128(fp128 %Val)
+      declare ppc_fp128 @llvm.round.ppcf128(ppc_fp128  %Val)
+
+Overview:
+"""""""""
+
+The '``llvm.round.*``' intrinsics returns the operand rounded to the
+nearest integer.
+
+Arguments:
+""""""""""
+
+The argument and return value are floating point numbers of the same
+type.
+
+Semantics:
+""""""""""
+
+This function returns the same values as the libm ``round``
+functions would, and handles error conditions in the same way.
+
 Bit Manipulation Intrinsics
 ---------------------------