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i386: Document memory size reference in assembler

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* doc/c-i386.texi: Document x/y/z instruction sufffixes in AT&T
	syntax and xmmword/ymmword/zmmword/fword/tbyte/oword ptr in
	Intel syntax.
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Lili Cui 2019-06-26 15:12:58 -07:00 committed by H.J. Lu
parent a68aa5d302
commit aa108c0c46
2 changed files with 16 additions and 5 deletions
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@ -1,3 +1,9 @@
2019-06-26 Lili Cui <lili.cui@intel.com>
* doc/c-i386.texi: Document x/y/z instruction sufffixes in AT&T
syntax and xmmword/ymmword/zmmword/fword/tbyte/oword ptr in
Intel syntax.
2019-06-25 Faraz Shahbazker <fshahbazker@wavecomp.com>
* config/tc-mips.c (macro) <M_LI>: Re-order MTHC1 with

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gas/doc/c-i386.texi
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@ -590,11 +590,16 @@ instruction, do @emph{not} have reversed order. @ref{i386-Bugs}.
In AT&T syntax the size of memory operands is determined from the last
character of the instruction mnemonic. Mnemonic suffixes of @samp{b},
@samp{w}, @samp{l} and @samp{q} specify byte (8-bit), word (16-bit), long
(32-bit) and quadruple word (64-bit) memory references. Intel syntax accomplishes
this by prefixing memory operands (@emph{not} the instruction mnemonics) with
@samp{byte ptr}, @samp{word ptr}, @samp{dword ptr} and @samp{qword ptr}. Thus,
Intel @samp{mov al, byte ptr @var{foo}} is @samp{movb @var{foo}, %al} in AT&T
syntax.
(32-bit) and quadruple word (64-bit) memory references. Mnemonic suffixes
of @samp{x}, @samp{y} and @samp{z} specify xmm (128-bit vector), ymm
(256-bit vector) and zmm (512-bit vector) memory references, only when there's
no other way to disambiguate an instruction. Intel syntax accomplishes this by
prefixing memory operands (@emph{not} the instruction mnemonics) with
@samp{byte ptr}, @samp{word ptr}, @samp{dword ptr}, @samp{qword ptr},
@samp{xmmword ptr}, @samp{ymmword ptr} and @samp{zmmword ptr}. Thus, Intel
syntax @samp{mov al, byte ptr @var{foo}} is @samp{movb @var{foo}, %al} in AT&T
syntax. In Intel syntax, @samp{fword ptr}, @samp{tbyte ptr} and
@samp{oword ptr} specify 48-bit, 80-bit and 128-bit memory references.
In 64-bit code, @samp{movabs} can be used to encode the @samp{mov}
instruction with the 64-bit displacement or immediate operand.