From c035816d7640e0df31a68f0d1d6d28ad07701d4e Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Fri, 8 Jun 2018 21:33:33 +0000 Subject: [PATCH] [LangRef] fptosi and fptoui return poison on overflow. I think we assume poison, not undef, for certain transforms we currently do. In any case, we should clarify the language here. (This sort of conversion is undefined behavior according to the C and C++ standards. And in practice, hardware implementations handle overflow inconsistently, so it would be difficult to define the result here.) Differential Revision: https://reviews.llvm.org/D47851 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334326 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/LangRef.rst | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/docs/LangRef.rst b/docs/LangRef.rst index 12490e91ecd..3d252e39f17 100644 --- a/docs/LangRef.rst +++ b/docs/LangRef.rst @@ -3275,13 +3275,15 @@ The following is the syntax for constant expressions: integer constant. TYPE must be a scalar or vector integer type. CST must be of scalar or vector floating-point type. Both CST and TYPE must be scalars, or vectors of the same number of elements. If the - value won't fit in the integer type, the results are undefined. + value won't fit in the integer type, the result is a + :ref:`poison value `. ``fptosi (CST to TYPE)`` Convert a floating-point constant to the corresponding signed integer constant. TYPE must be a scalar or vector integer type. CST must be of scalar or vector floating-point type. Both CST and TYPE must be scalars, or vectors of the same number of elements. If the - value won't fit in the integer type, the results are undefined. + value won't fit in the integer type, the result is a + :ref:`poison value `. ``uitofp (CST to TYPE)`` Convert an unsigned integer constant to the corresponding floating-point constant. TYPE must be a scalar or vector floating-point @@ -8765,8 +8767,8 @@ Semantics: The '``fptoui``' instruction converts its :ref:`floating-point ` operand into the nearest (rounding towards zero) -unsigned integer value. If the value cannot fit in ``ty2``, the results -are undefined. +unsigned integer value. If the value cannot fit in ``ty2``, the result +is a :ref:`poison value `. Example: """""""" @@ -8807,8 +8809,8 @@ Semantics: The '``fptosi``' instruction converts its :ref:`floating-point ` operand into the nearest (rounding towards zero) -signed integer value. If the value cannot fit in ``ty2``, the results -are undefined. +signed integer value. If the value cannot fit in ``ty2``, the result +is a :ref:`poison value `. Example: """"""""