On Mon, Sep 06, 2021 at 10:05:00AM +0800, Hongtao Liu wrote:
> @@ -1076,9 +1076,11 @@ 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. The @code{_Float16} type is supported on AArch64
> -systems by default, and on ARM systems when the IEEE format for 16-bit
> -floating-point types is selected with @option{-mfp16-format=ieee}.
> -GCC does not currently support @code{_Float128x} on any systems.
> +systems by default, and also on x86 systems with @code{target("sse2")}
> +for both C and C++.
> +On ARM systems when the IEEE format for 16-bit floating-point types is
> +selected with @option{-mfp16-format=ieee}.
This isn't a sentence. I think it should be:
The @code{_Float16} type is supported on AArch64 systems by default,
on ARM systems when the IEEE format for 16-bit floating-point types is
selected with @option{-mfp16-format=ieee} and, for both C and C++, on x86
systems with SSE2 enabled.
> 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
> @@ -1108,6 +1110,10 @@ On ARM and AArch64 targets, GCC supports
> half-precision (16-bit) floating
> point via the @code{__fp16} type defined in the ARM C Language Extensions.
> On ARM systems, you must enable this type explicitly with the
> @option{-mfp16-format} command-line option in order to use it.
> +On x86 targets with @code{target("sse2")} and above, GCC supports
> +half-precision (16-bit) floating point via the @code{_Float16} type.
> +For C++, x86 provides a builtin type named @code{_Float16} which contains
> +same data format as C.
Again, I'd write with SSE2 enabled, there are many ways to enable SSE2,
-msse2, -mavx, -mavx512f, ... on the command line, or various target
attributes.
Jakub
