From: Eric Botcazou <ebotcazou@adacore.com>
Date: Mon, 18 Jan 2021 18:30:27 +0000 (+0100)
Subject: [Ada] Document a few more characteristics of floating-point support
X-Git-Tag: basepoints/gcc-13~7775
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d07cc0d1262366e4b1e6f00ea226b5b9a891b445;p=thirdparty%2Fgcc.git

[Ada] Document a few more characteristics of floating-point support

gcc/ada/

	* doc/gnat_rm/implementation_defined_characteristics.rst (3.5.7):
	Mention the IEEE standard explicitly.  Use current format names.
	Document assumed rounding mode and new features of I/O support.
	* gnat_rm.texi: Regenerate.
---

diff --git a/gcc/ada/doc/gnat_rm/implementation_defined_characteristics.rst b/gcc/ada/doc/gnat_rm/implementation_defined_characteristics.rst
index 10fcfc93c1d0..8d0be38d9aaf 100644
--- a/gcc/ada/doc/gnat_rm/implementation_defined_characteristics.rst
+++ b/gcc/ada/doc/gnat_rm/implementation_defined_characteristics.rst
@@ -129,20 +129,29 @@ There are no nonstandard real types.
   "What combinations of requested decimal precision and range
   are supported for floating point types.  See 3.5.7(7)."
 
-The precision and range is as defined by the IEEE standard.
+The precision and range are defined by the IEEE Standard for Floating-Point
+Arithmetic (IEEE 754-2019).
 
 *
   "The predefined floating point types declared in
   ``Standard``.  See 3.5.7(16)."
 
-====================== ====================================================
+====================== ===============================================
 Type                   Representation
-====================== ====================================================
-*Short_Float*          32 bit IEEE short
-*Float*                (Short) 32 bit IEEE short
-*Long_Float*           64 bit IEEE long
-*Long_Long_Float*      64 bit IEEE long (80 bit IEEE long on x86 processors)
-====================== ====================================================
+====================== ===============================================
+*Short_Float*          IEEE Binary32 (Single)
+*Float*                IEEE Binary32 (Single)
+*Long_Float*           IEEE Binary64 (Double)
+*Long_Long_Float*      IEEE Binary64 (Double) on non-x86 architectures
+                       IEEE 80-bit Extended on x86 architecture
+====================== ===============================================
+
+The default rounding mode specified by the IEEE 754 Standard is assumed for
+static computations, i.e. round to nearest, ties to even. The input routines
+yield correctly rounded values for Short_Float, Float and Long_Float at least.
+The output routines can compute up to twice as many exact digits as the value
+of ``T'Digits`` for any type, for example 30 digits for Long_Float; if more
+digits are requested, zeros are printed.
 
 *
   "The small of an ordinary fixed point type.  See 3.5.9(8)."
diff --git a/gcc/ada/gnat_rm.texi b/gcc/ada/gnat_rm.texi
index 9427dccf674e..569b9812eff8 100644
--- a/gcc/ada/gnat_rm.texi
+++ b/gcc/ada/gnat_rm.texi
@@ -15667,7 +15667,8 @@ There are no nonstandard real types.
 are supported for floating point types.  See 3.5.7(7)."
 @end itemize
 
-The precision and range is as defined by the IEEE standard.
+The precision and range are defined by the IEEE Standard for Floating-Point
+Arithmetic (IEEE 754-2019).
 
 
 @itemize *
@@ -15678,7 +15679,7 @@ The precision and range is as defined by the IEEE standard.
 @end itemize
 
 
-@multitable {xxxxxxxxxxxxxxxxxxxxxxxx} {xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx} 
+@multitable {xxxxxxxxxxxxxxxxxxxxxxxx} {xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx} 
 @headitem
 
 Type
@@ -15693,7 +15694,7 @@ Representation
 
 @tab
 
-32 bit IEEE short
+IEEE Binary32 (Single)
 
 @item
 
@@ -15701,7 +15702,7 @@ Representation
 
 @tab
 
-(Short) 32 bit IEEE short
+IEEE Binary32 (Single)
 
 @item
 
@@ -15709,7 +15710,7 @@ Representation
 
 @tab
 
-64 bit IEEE long
+IEEE Binary64 (Double)
 
 @item
 
@@ -15717,11 +15718,19 @@ Representation
 
 @tab
 
-64 bit IEEE long (80 bit IEEE long on x86 processors)
+IEEE Binary64 (Double) on non-x86 architectures
+IEEE 80-bit Extended on x86 architecture
 
 @end multitable
 
 
+The default rounding mode specified by the IEEE 754 Standard is assumed for
+static computations, i.e. round to nearest, ties to even. The input routines
+yield correctly rounded values for Short_Float, Float and Long_Float at least.
+The output routines can compute up to twice as many exact digits as the value
+of @code{T'Digits} for any type, for example 30 digits for Long_Float; if more
+digits are requested, zeros are printed.
+
 
 @itemize *