diff options
Diffstat (limited to 'gas/doc/c-i386.texi')
| -rw-r--r-- | gas/doc/c-i386.texi | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/gas/doc/c-i386.texi b/gas/doc/c-i386.texi index 6b2def0..965e0ff 100644 --- a/gas/doc/c-i386.texi +++ b/gas/doc/c-i386.texi @@ -411,6 +411,28 @@ with 01, 10 and 11 RC bits, respectively. This option specifies that the assembler should accept only AMD64 or Intel64 ISA in 64-bit mode. The default is to accept both. +@cindex @samp{-O0} option, i386 +@cindex @samp{-O0} option, x86-64 +@cindex @samp{-O} option, i386 +@cindex @samp{-O} option, x86-64 +@cindex @samp{-O1} option, i386 +@cindex @samp{-O1} option, x86-64 +@cindex @samp{-O2} option, i386 +@cindex @samp{-O2} option, x86-64 +@cindex @samp{-Os} option, i386 +@cindex @samp{-Os} option, x86-64 +@item -O0 | -O | -O1 | -O2 | -Os +Optimize instruction encoding with smaller instruction size. @samp{-O} +and @samp{-O1} encode 64-bit register load instructions with 64-bit +immediate as 32-bit register load instructions with 31-bit or 32-bits +immediates and encode 64-bit register clearing instructions with 32-bit +register clearing instructions. @samp{-O2} includes @samp{-O1} +optimization plus encodes 256-bit and 512-bit vector register clearing +instructions with 128-bit vector register clearing instructions. +@samp{-Os} includes @samp{-O2} optimization plus encodes 16-bit, 32-bit +and 64-bit register tests with immediate as 8-bit register test with +immediate. @samp{-O0} turns off this optimization. + @end table @c man end @@ -647,6 +669,9 @@ Different encoding options can be specified via pseudo prefixes: @samp{@{rex@}} -- prefer REX prefix for integer and legacy vector instructions (x86-64 only). Note that this differs from the @samp{rex} prefix which generates REX prefix unconditionally. + +@item +@samp{@{nooptimize@}} -- disable instruction size optimization. @end itemize @cindex conversion instructions, i386 |