diff options
Diffstat (limited to 'gas/doc/c-arm.texi')
| -rw-r--r-- | gas/doc/c-arm.texi | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/gas/doc/c-arm.texi b/gas/doc/c-arm.texi index 6fb8c06..8fc2972 100644 --- a/gas/doc/c-arm.texi +++ b/gas/doc/c-arm.texi @@ -391,7 +391,7 @@ example: @cindex @code{unreq} directive, ARM @item .unreq @var{alias-name} This undefines a register alias which was previously defined using the -@code{req} directive. For example: +@code{req}, @code{dn} or @code{qn} directives. For example: @smallexample foo .req r0 @@ -402,6 +402,36 @@ An error occurs if the name is undefined. Note - this pseudo op can be used to delete builtin in register name aliases (eg 'r0'). This should only be done if it is really necessary. +@cindex @code{dn} and @code{qn} directives, ARM +@item @var{name} .dn @var{register name} [@var{.type}] [@var{[index]}] +@item @var{name} .qn @var{register name} [@var{.type}] [@var{[index]}] + +The @code{dn} and @code{qn} directives are used to create typed +and/or indexed register aliases for use in Advanced SIMD Extension +(Neon) instructions. The former should be used to create aliases +of double-precision registers, and the latter to create aliases of +quad-precision registers. + +If these directives are used to create typed aliases, those aliases can +be used in Neon instructions instead of writing types after the mnemonic +or after each operand. For example: + +@smallexample + x .dn d2.f32 + y .dn d3.f32 + z .dn d4.f32[1] + vmul x,y,z +@end smallexample + +This is equivalent to writing the following: + +@smallexample + vmul.f32 d2,d3,d4[1] +@end smallexample + +Aliases created using @code{dn} or @code{qn} can be destroyed using +@code{unreq}. + @cindex @code{code} directive, ARM @item .code @code{[16|32]} This directive selects the instruction set being generated. The value 16 |