[PATCH 05/11] x86: introduce .hfloat directive

[H.J. Lu]

On Thu, Jul 22, 2021 at 11:54 PM Jan Beulich <jbeulich@suse.com> wrote:
>
> This is to be able to generate data passed to {,V}CVTPH2PS and acted
> upon by AVX512-FP16 insns. To be able to also use the hex forms
> supported for other floating point formats, a small addition to the
> generic hex_float() is needed.
>
> Extend existing x86 testcases.

OK if all prerequisites have been approved.  Thanks.

> ---
> I wonder whether introduction (in generic code) of .{dc,dcb,ds}.h
> directives wouldn't be warranted. The format not being supported by all
> architectures if no different from, in particular, the .x or .p forms.

If they aren't used for all architectures, keep them to x86.

> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -511,7 +511,7 @@ const char EXP_CHARS[] = "eE";
>  /* Chars that mean this number is a floating point constant
>     As in 0f12.456
>     or    0d1.2345e12.  */
> -const char FLT_CHARS[] = "fFdDxX";
> +const char FLT_CHARS[] = "fFdDxXhH";
>
>  /* Tables for lexical analysis.  */
>  static char mnemonic_chars[256];
> @@ -1352,6 +1352,7 @@ const pseudo_typeS md_pseudo_table[] =
>    {"ffloat", float_cons, 'f'},
>    {"dfloat", float_cons, 'd'},
>    {"tfloat", float_cons, 'x'},
> +  {"hfloat", float_cons, 'h'},
>    {"value", cons, 2},
>    {"slong", signed_cons, 4},
>    {"noopt", s_ignore, 0},
> --- a/gas/doc/c-i386.texi
> +++ b/gas/doc/c-i386.texi
> @@ -1311,18 +1311,21 @@ data type.  Constructors build these dat
>  @cindex @code{single} directive, i386
>  @cindex @code{double} directive, i386
>  @cindex @code{tfloat} directive, i386
> +@cindex @code{hfloat} directive, i386
>  @cindex @code{float} directive, x86-64
>  @cindex @code{single} directive, x86-64
>  @cindex @code{double} directive, x86-64
>  @cindex @code{tfloat} directive, x86-64
> +@cindex @code{hfloat} directive, x86-64
>  @itemize @bullet
>  @item
>  Floating point constructors are @samp{.float} or @samp{.single},
> -@samp{.double}, and @samp{.tfloat} for 32-, 64-, and 80-bit formats.
> -These correspond to instruction mnemonic suffixes @samp{s}, @samp{l},
> -and @samp{t}. @samp{t} stands for 80-bit (ten byte) real.  The 80387
> -only supports this format via the @samp{fldt} (load 80-bit real to stack
> -top) and @samp{fstpt} (store 80-bit real and pop stack) instructions.
> +@samp{.double}, @samp{.tfloat}, and @samp{.hfloat} for 32-, 64-, 80-, and
> +16-bit formats respectively. The former three correspond to instruction
> +mnemonic suffixes @samp{s}, @samp{l}, and @samp{t}. @samp{t} stands for
> +80-bit (ten byte) real.  The 80387 only supports this format via the
> +@samp{fldt} (load 80-bit real to stack top) and @samp{fstpt} (store 80-bit
> +real and pop stack) instructions.
>
>  @cindex @code{word} directive, i386
>  @cindex @code{long} directive, i386
> --- a/gas/read.c
> +++ b/gas/read.c
> @@ -4852,6 +4852,11 @@ hex_float (int float_type, char *bytes)
>
>    switch (float_type)
>      {
> +    case 'h':
> +    case 'H':
> +      length = 2;
> +      break;
> +
>      case 'f':
>      case 'F':
>      case 's':
> --- a/gas/testsuite/gas/i386/fp-elf32.d
> +++ b/gas/testsuite/gas/i386/fp-elf32.d
> @@ -14,3 +14,4 @@ Contents of section .data:
>   0060 00000000 00000080 fe3f0000 00000000  .*
>   0070 00000080 fdbf0000 00000000 00000080  .*
>   0080 ff030000 aaaaaaaa aaaaaaaa aaaaaaaa  .*
> + 0090 003c00c0 003c5555 55555555 55555555  .*
> --- a/gas/testsuite/gas/i386/fp-elf64.d
> +++ b/gas/testsuite/gas/i386/fp-elf64.d
> @@ -14,3 +14,4 @@ Contents of section .data:
>   0060 00000000 00000080 fe3f0000 00000000  .*
>   0070 00000000 00000080 fdbf0000 00000000  .*
>   0080 00000000 00000080 ff030000 00000000  .*
> + 0090 003c00c0 003c5555 55555555 55555555  .*
> --- a/gas/testsuite/gas/i386/fp.d
> +++ b/gas/testsuite/gas/i386/fp.d
> @@ -12,3 +12,4 @@ Contents of section .data:
>   0050 ffffffff ffffffff ffffcccc cccccccc  .*
>   0060 00000000 00000080 fe3f0000 00000000  .*
>   0070 0080fdbf 00000000 00000080 ff03aaaa  .*
> + 0080 003c00c0 003c5555 55555555 55555555  .*
> --- a/gas/testsuite/gas/i386/fp.s
> +++ b/gas/testsuite/gas/i386/fp.s
> @@ -29,3 +29,6 @@
>         .dc.x 0x:bffd80
>         .dcb.x 1, 0x:03ff80
>         .p2align 4,0xaa
> +
> +       .hfloat 1, -2, 0x:3c00
> +       .p2align 4,0x55
>


-- 
H.J.