[FPEnv] Add fptosi and fptoui constrained intrinsics.

This implements constrained floating point intrinsics for FP to signed and
unsigned integers.

Quoting from D32319:
The purpose of the constrained intrinsics is to force the optimizer to
respect the restrictions that will be necessary to support things like the
STDC FENV_ACCESS ON pragma without interfering with optimizations when
these restrictions are not needed.

Reviewed by:	Andrew Kaylor, Craig Topper, Hal Finkel, Cameron McInally, Roman Lebedev, Kit Barton
Approved by:	Craig Topper
Differential Revision:	http://reviews.llvm.org/D63782

llvm-svn: 370228

1 files changed, 66 insertions, 0 deletions

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 55ba443dddf..39095303361 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -15280,6 +15280,72 @@ The result produced is the product of the first two operands added to the third
 operand computed with infinite precision, and then rounded to the target
 precision.
 
+'``llvm.experimental.constrained.fptoui``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+      declare <ty2>
+      @llvm.experimental.constrained.fptoui(<type> <value>,
+                                          metadata <exception behavior>)
+
+Overview:
+"""""""""
+
+The '``llvm.experimental.constrained.fptoui``' intrinsic converts a 
+floating-point ``value`` to its unsigned integer equivalent of type ``ty2``.
+
+Arguments:
+""""""""""
+
+The first argument to the '``llvm.experimental.constrained.fptoui``'
+intrinsic must be :ref:`floating point <t_floating>` or :ref:`vector
+<t_vector>` of floating point values.
+
+The second argument specifies the exception behavior as described above.
+
+Semantics:
+""""""""""
+
+The result produced is an unsigned integer converted from the floating
+point operand. The value is truncated, so it is rounded towards zero.
+
+'``llvm.experimental.constrained.fptosi``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+      declare <ty2>
+      @llvm.experimental.constrained.fptosi(<type> <value>,
+                                          metadata <exception behavior>)
+
+Overview:
+"""""""""
+
+The '``llvm.experimental.constrained.fptosi``' intrinsic converts 
+:ref:`floating-point <t_floating>` ``value`` to type ``ty2``.
+
+Arguments:
+""""""""""
+
+The first argument to the '``llvm.experimental.constrained.fptosi``'
+intrinsic must be :ref:`floating point <t_floating>` or :ref:`vector
+<t_vector>` of floating point values. 
+
+The second argument specifies the exception behavior as described above.
+
+Semantics:
+""""""""""
+
+The result produced is a signed integer converted from the floating
+point operand. The value is truncated, so it is rounded towards zero.
+
 '``llvm.experimental.constrained.fptrunc``' Intrinsic
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^