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author | Chang S. Bae <changseok.bae@gmail.com> | 2018-10-29 16:16:16 -0700 |
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committer | Cyrill Gorcunov <gorcunov@gmail.com> | 2018-10-30 10:11:08 +0300 |
commit | 4310eb9d42b1775494cd68bf7bd1e90caab4bace (patch) | |
tree | 29b9c1a4c6fdc5480d29fb0317150eebd3d5cce3 | |
parent | 4b5b737d4991578b1918303dc0fd9c9ab5c7ce4f (diff) | |
download | nasm-4310eb9d42b1775494cd68bf7bd1e90caab4bace.tar.gz |
doc: Add a description for a useful case of mangling symbols
Signed-off-by: Chang S. Bae <changseok.bae@gmail.com>
-rw-r--r-- | doc/nasmdoc.src | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/doc/nasmdoc.src b/doc/nasmdoc.src index 782914d8..0aac8562 100644 --- a/doc/nasmdoc.src +++ b/doc/nasmdoc.src @@ -4707,6 +4707,18 @@ This is a macro implemented as a \c{%pragma}: Commandline option is also possible. See also \k{opt-pfix}. +Some tool chain is aware of a particular prefix for its own optimization +options, such as code elimination. For instance, Mach-O backend has a +linker that uses a simplistic naming scheme to chunk up sections into a +meta section. When the \c{subsections_via_symbols} directive +(\k{macho-ssvs}) is declared, each symbol is the start of a +separate block. The meta section is, then, defined to include sections +before the one that starts with a 'L'. \c{LPREFIX} is useful here to mark +all local symbols with the 'L' prefix to be excluded to the meta section. +It converts local symbols compatible with the particular tool chain. +Note that local symbols declared with \c{STATIC} (\k{static}) +are excluded from the symbol mangling and also not marked as global. + \H{gen-namespace} \i\c{OUTPUT}, \i\c{DEBUG}: Generic Namespaces @@ -5823,9 +5835,9 @@ right-hand side of the \c{WRT} operator: \S{macho-ssvs} \c{macho} specfic directive \i\c{subsections_via_symbols} The directive \c{subsections_via_symbols} sets the -\c{MH_SUBSECTIONS_VIA_SYMBOLS} flag in the Mach-O header, which tells -the linker that the symbols in the file matches the conventions -required to allow for link-time dead code elimination. +\c{MH_SUBSECTIONS_VIA_SYMBOLS} flag in the Mach-O header, that effectively +separates a block (or a subsection) based on a symbol. It is often used +for eliminating dead codes by a linker. This directive takes no arguments. |