diff options
Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 5285e002d7e..5124883ae5c 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -927,6 +927,8 @@ examine and set these two fictitious variables with your debugger. @node Floating Types @section Additional Floating Types @cindex additional floating types +@cindex @code{_Float@var{n}} data types +@cindex @code{_Float@var{n}x} data types @cindex @code{__float80} data type @cindex @code{__float128} data type @cindex @code{__ibm128} data type @@ -935,9 +937,19 @@ examine and set these two fictitious variables with your debugger. @cindex @code{W} floating point suffix @cindex @code{Q} floating point suffix -As an extension, GNU C supports additional floating +ISO/IEC TS 18661-3:2015 defines C support for additional floating +types @code{_Float@var{n}} and @code{_Float@var{n}x}, and GCC supports +these type names; the set of types supported depends on the target +architecture. These types are not supported when compiling C++. +Constants with these types use suffixes @code{f@var{n}} or +@code{F@var{n}} and @code{f@var{n}x} or @code{F@var{n}x}. These type +names can be used together with @code{_Complex} to declare complex +types. + +As an extension, GNU C and GNU C++ support additional floating types, @code{__float80} and @code{__float128} to support 80-bit -(@code{XFmode}) and 128-bit (@code{TFmode}) floating types. +(@code{XFmode}) and 128-bit (@code{TFmode}) floating types; these are +aliases for the type names @code{_Float64x} and @code{_Float128}. Support for additional types includes the arithmetic operators: add, subtract, multiply, divide; unary arithmetic operators; relational operators; equality operators; and conversions to and from @@ -954,9 +966,11 @@ typedef _Complex float __attribute__((mode(TC))) _Complex128; typedef _Complex float __attribute__((mode(XC))) _Complex80; @end smallexample -In order to use @code{__float128} and @code{__ibm128} on PowerPC Linux +In order to use @code{_Float128}, @code{__float128} and +@code{__ibm128} on PowerPC Linux systems, you must use the @option{-mfloat128}. It is expected in -future versions of GCC that @code{__float128} will be enabled +future versions of GCC that @code{_Float128} and @code{__float128} +will be enabled automatically. In addition, there are currently problems in using the complex @code{__float128} type. When these problems are fixed, you would use the following syntax to declare @code{_Complex128} to be a @@ -976,7 +990,14 @@ Not all targets support additional floating-point types. IA-64 targets. The @code{__float128} type is supported on hppa HP-UX. The @code{__float128} type is supported on PowerPC 64-bit Linux systems by default if the vector scalar instruction set (VSX) is -enabled. +enabled. The @code{_Float128} type is supported on all systems where +@code{__float128} is supported or where @code{long double} has the +IEEE binary128 format. The @code{_Float64x} type is supported on all +systems where @code{__float128} is supported. The @code{_Float32} +type is supported on all systems supporting IEEE binary32; the +@code{_Float64} and @code{Float32x} types are supported on all systems +supporting IEEE binary64. GCC does not currently support +@code{_Float16} or @code{_Float128x} on any systems. On the PowerPC, @code{__ibm128} provides access to the IBM extended double format, and it is intended to be used by the library functions |