x86: introduce .bfloat16 directive

This is to be able to generate data acted upon by AVX512-BF16 and
AMX-BF16 insns. While not part of the IEEE standard, the format is
sufficiently standardized to warrant handling in config/atof-ieee.c.
Arm, where custom handling was implemented, may want to leverage this as
well. 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.
This commit is contained in:
Jan Beulich 2021-08-11 08:33:49 +02:00
parent 7d19d09629
commit de133cf98c
8 changed files with 32 additions and 14 deletions

View File

@ -27,6 +27,7 @@ extern FLONUM_TYPE generic_floating_point_number;
/* Don't count the gap in the m68k extended precision format. */
#define MAX_PRECISION 5
#define H_PRECISION 1
#define B_PRECISION 1 /* Not strictly IEEE, but handled here anyway. */
#define F_PRECISION 2
#define D_PRECISION 4
#define X_PRECISION 5
@ -243,6 +244,12 @@ atof_ieee (char *str, /* Text to convert to binary. */
exponent_bits = 5;
break;
case 'b':
case 'B':
precision = B_PRECISION;
exponent_bits = 8;
break;
case 'f':
case 'F':
case 's':
@ -368,9 +375,9 @@ gen_to_words (LITTLENUM_TYPE *words, int precision, long exponent_bits)
as_warn (_("Infinities are not supported by this target"));
/* +INF: Do the right thing. */
if (precision == H_PRECISION)
if (precision == H_PRECISION /* also B_PRECISION */)
{
words[0] = 0x7c00;
words[0] = exponent_bits == 5 ? 0x7c00 : 0x7f80;
}
else if (precision == F_PRECISION)
{
@ -413,9 +420,9 @@ gen_to_words (LITTLENUM_TYPE *words, int precision, long exponent_bits)
as_warn (_("Infinities are not supported by this target"));
/* Negative INF. */
if (precision == H_PRECISION)
if (precision == H_PRECISION /* also B_PRECISION */)
{
words[0] = 0xfc00;
words[0] = exponent_bits == 5 ? 0xfc00 : 0xff80;
}
else if (precision == F_PRECISION)
{
@ -777,6 +784,11 @@ ieee_md_atof (int type,
prec = H_PRECISION;
break;
case 'B':
case 'b':
prec = B_PRECISION;
break;
case 'f':
case 'F':
case 's':

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@ -512,7 +512,7 @@ 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[] = "fFdDxXhH";
const char FLT_CHARS[] = "fFdDxXhHbB";
/* Tables for lexical analysis. */
static char mnemonic_chars[256];
@ -1357,6 +1357,7 @@ const pseudo_typeS md_pseudo_table[] =
{"dfloat", float_cons, 'd'},
{"tfloat", float_cons, 'x'},
{"hfloat", float_cons, 'h'},
{"bfloat16", float_cons, 'b'},
{"value", cons, 2},
{"slong", signed_cons, 4},
{"noopt", s_ignore, 0},

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@ -1314,20 +1314,22 @@ data type. Constructors build these data types into memory.
@cindex @code{double} directive, i386
@cindex @code{tfloat} directive, i386
@cindex @code{hfloat} directive, i386
@cindex @code{bfloat16} 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
@cindex @code{bfloat16} directive, x86-64
@itemize @bullet
@item
Floating point constructors are @samp{.float} or @samp{.single},
@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.
@samp{.double}, @samp{.tfloat}, @samp{.hfloat}, and @samp{.bfloat16} for 32-,
64-, 80-, and 16-bit (two flavors) 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

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@ -4852,6 +4852,8 @@ hex_float (int float_type, char *bytes)
switch (float_type)
{
case 'b':
case 'B':
case 'h':
case 'H':
length = 2;

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@ -14,4 +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 .*
0090 003c00c0 003c803f 00c0803f 55555555 .*

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@ -14,4 +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 .*
0090 003c00c0 003c803f 00c0803f 55555555 .*

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@ -12,4 +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 .*
0080 003c00c0 003c803f 00c0803f 55555555 .*

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@ -31,4 +31,5 @@
.p2align 4,0xaa
.hfloat 1, -2, 0x:3c00
.bfloat16 1, -2, 0x:3f80
.p2align 4,0x55