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Diffstat (limited to 'gas/doc/as.texi')
| -rw-r--r-- | gas/doc/as.texi | 32 |
1 files changed, 21 insertions, 11 deletions
diff --git a/gas/doc/as.texi b/gas/doc/as.texi index f2a0314..b88c1f9 100644 --- a/gas/doc/as.texi +++ b/gas/doc/as.texi @@ -4446,6 +4446,7 @@ Some machine configurations provide additional directives. * MRI:: @code{.mri @var{val}} * Noaltmacro:: @code{.noaltmacro} * Nolist:: @code{.nolist} +* Nop:: @code{.nop} * Nops:: @code{.nops @var{size}[, @var{control}]} * Octa:: @code{.octa @var{bignums}} * Offset:: @code{.offset @var{loc}} @@ -6157,22 +6158,31 @@ internal counter (which is zero initially). @code{.list} increments the counter, and @code{.nolist} decrements it. Assembly listings are generated whenever the counter is greater than zero. +@node Nop +@section @code{.nop} + +@cindex @code{nop} directive +@cindex filling memory with no-op instructions +This directive emits a single no-op instruction. It is provided on all +architectures, allowing the creation of architecture neutral tests involving +actual code. The size of the generated instruction is target specific. The +instruction does affect the generation of DWARF debug line information. + @node Nops @section @code{.nops @var{size}[, @var{control}]} @cindex @code{nops} directive @cindex filling memory with no-op instructions -This directive emits @var{size} bytes filled with no-op instructions. -@var{size} is absolute expression, which must be a positve value. -@var{control} controls how no-op instructions should be generated. If -the comma and @var{control} are omitted, @var{control} is assumed to be -zero. - -Note: For Intel 80386 and AMD x86-64 targets, @var{control} specifies -the size limit of a no-op instruction. The valid values of @var{control} -are between 0 and 4 in 16-bit mode, between 0 and 7 when tuning for -older processors in 32-bit mode, between 0 and 11 in 64-bit mode or when -tuning for newer processors in 32-bit mode. When 0 is used, the no-op +This directive emits no-op instructions. It is specific to the Intel 80386 and +AMD x86-64 targets. It takes a @var{size} argument and generates @var{size} +bytes of no-op instructions. @var{size} must be absolute and positive. These +bytes do not affect the generation of DWARF debug line information. + +The optional @var{control} argument specifies a size limit for a single no-op +instruction. If not provided then a value of 0 is assumed. The valid values +of @var{control} are between 0 and 4 in 16-bit mode, between 0 and 7 when +tuning for older processors in 32-bit mode, between 0 and 11 in 64-bit mode or +when tuning for newer processors in 32-bit mode. When 0 is used, the no-op instruction size limit is set to the maximum supported size. @node Octa |