This patch adds the documentation.
I have built the compiler with this patch and the previous subpatches (1-14).
I have bootstrapped the compiler with all 16 subpatches installed, and there
were no regressions. Is it ok to install in the trunk?
2015-10-22 Michael Meissner <meiss...@linux.vnet.ibm.com>
* doc/extend.texi (Floating Types): Document __ibm128 and
__float128 on PowerPC.
* doc/invoke.texi (RS/6000 and PowerPC Options): Document
-mfloat128 and -mno-float128.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
Index: gcc/doc/extend.texi
===================================================================
--- gcc/doc/extend.texi (revision 229182)
+++ gcc/doc/extend.texi (working copy)
@@ -929,6 +929,7 @@ examine and set these two fictitious var
@cindex additional floating types
@cindex @code{__float80} data type
@cindex @code{__float128} data type
+@cindex @code{__ibm128} data type
@cindex @code{w} floating point suffix
@cindex @code{q} floating point suffix
@cindex @code{W} floating point suffix
@@ -941,19 +942,39 @@ Support for additional types includes th
add, subtract, multiply, divide; unary arithmetic operators;
relational operators; equality operators; and conversions to and from
integer and other floating types. Use a suffix @samp{w} or @samp{W}
-in a literal constant of type @code{__float80} and @samp{q} or @samp{Q}
-for @code{_float128}. You can declare complex types using the
-corresponding internal complex type, @code{XCmode} for @code{__float80}
-type and @code{TCmode} for @code{__float128} type:
+in a literal constant of type @code{__float80} or type
+@code{__ibm128}. Use a suffix @samp{q} or @samp{Q} for @code{_float128}.
+
+On the i386, x86_64, IA-64, and HP-UX targets, you can declare complex
+types using the corresponding internal complex type, @code{XCmode} for
+@code{__float80} type and @code{TCmode} for @code{__float128} type:
@smallexample
typedef _Complex float __attribute__((mode(TC))) _Complex128;
typedef _Complex float __attribute__((mode(XC))) _Complex80;
@end smallexample
+On PowerPC Linux, Freebsd and Darwin systems, the default for
+@code{long double} is to use the IBM extended floating point format
+that uses a pair of @code{double} values to extend the precision.
+This means that the mode @code{TCmode} was already used by the
+traditional IBM long double format, and you would need to use the mode
+@code{KCmode}:
+
+@smallexample
+typedef _Complex float __attribute__((mode(KC))) _Complex128;
+@end smallexample
+
Not all targets support additional floating-point types. @code{__float80}
and @code{__float128} types are supported on x86 and IA-64 targets.
-The @code{__float128} type is supported on hppa HP-UX targets.
+The @code{__float128} type is supported on hppa HP-UX.
+The @code{__float128} type is supported on PowerPC systems by default
+if the vector scalar instruction set (VSX) is enabled.
+
+On the PowerPC, @code{__ibm128} provides access to the IBM extended
+double format, and it is intended to be used by the library functions
+that handle conversions if/when long double is changed to be IEEE
+128-bit floating point.
@node Half-Precision
@section Half-Precision Floating Point
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 229182)
+++ gcc/doc/invoke.texi (working copy)
@@ -946,7 +946,8 @@ See RS/6000 and PowerPC Options.
-mquad-memory-atomic -mno-quad-memory-atomic @gol
-mcompat-align-parm -mno-compat-align-parm @gol
-mupper-regs-df -mno-upper-regs-df -mupper-regs-sf -mno-upper-regs-sf @gol
--mupper-regs -mno-upper-regs}
+-mupper-regs -mno-upper-regs @gol
+-mfloat128 -mno-float128}
@emph{RX Options}
@gccoptlist{-m64bit-doubles -m32bit-doubles -fpu -nofpu@gol
@@ -19519,6 +19520,17 @@ floating point register set, depending o
If the @option{-mno-upper-regs} option is used, it turns off both
@option{-mupper-regs-sf} and @option{-mupper-regs-df} options.
+@item -mfloat128
+@itemx -mno-float128
+@opindex mfloat128
+@opindex mno-float128
+Enable/disable the @var{__float128} keyword for IEEE 128-bit floating point
+and use software emulation for IEEE 128-bit floating point.
+
+The VSX instruction set (@option{-mvsx}, @option{-mcpu=power7}, or
+@option{-mcpu=power8}) must be enabled to use the @option{-mfloat128}
+option.
+
@item -mfloat-gprs=@var{yes/single/double/no}
@itemx -mfloat-gprs
@opindex mfloat-gprs
