| Message ID | 20171016055931.30079-1-sebastian.huber@embedded-brains.de |
|---|---|
| State | New |
| Headers | show |
| Series | Update -ffunction/data-sections documentation | expand |
On 10/15/2017 11:59 PM, Sebastian Huber wrote: > gcc/ > * invoke.texi (ffunction-sections and fdata-sections): Update. > --- > gcc/doc/invoke.texi | 32 ++++++++++++++++++++------------ > 1 file changed, 20 insertions(+), 12 deletions(-) > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index 4e7dfb33c31..7bc051a1fc5 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -9712,18 +9712,26 @@ file if the target supports arbitrary sections. The name of the > function or the name of the data item determines the section's name > in the output file. > > -Use these options on systems where the linker can perform optimizations > -to improve locality of reference in the instruction space. Most systems > -using the ELF object format and SPARC processors running Solaris 2 have > -linkers with such optimizations. AIX may have these optimizations in > -the future. > - > -Only use these options when there are significant benefits from doing > -so. When you specify these options, the assembler and linker > -create larger object and executable files and are also slower. > -You cannot use @command{gprof} on all systems if you > -specify this option, and you may have problems with debugging if > -you specify both this option and @option{-g}. > +Use these options on systems where the linker can perform optimizations to > +improve locality of reference in the instruction space. Most systems using the > +ELF object format have linkers with such optimizations. On AIX, the linker > +rearranges sections (CSECTs) based on the call graph. The performance impact > +varies. > + > +Together with a linker garbage collection (linker @option{--gc-sections} > +option) these options may lead to smaller statically linked executables (after statically-linked > +stripping). > + > +On ELF/DWARF systems these options do not degenerate the quality of the debug > +information. There could be issues with other object files/debug info formats. > + > +Only use these options when there are significant benefits from doing so. When > +you specify these options, the assembler and linker create larger object and > +executable files and are also slower. These options affect code generation. > +They prevent optimzations by the compiler and assembler using relative optimizations > +locations inside a translation unit since the locations are unknown until > +link-time. link time > +An examples for such an optimization is a call to short call > +relaxation. I'd rewrite the last sentence as An example of such an optimization is relaxing calls to short call instructions. I think the patch is OK with those nits fixed. -Sandra
On 17/10/17 21:39, Sandra Loosemore wrote: > > I think the patch is OK with those nits fixed. Thanks, for the review. Committed as: https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=253842
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 4e7dfb33c31..7bc051a1fc5 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -9712,18 +9712,26 @@ file if the target supports arbitrary sections. The name of the function or the name of the data item determines the section's name in the output file. -Use these options on systems where the linker can perform optimizations -to improve locality of reference in the instruction space. Most systems -using the ELF object format and SPARC processors running Solaris 2 have -linkers with such optimizations. AIX may have these optimizations in -the future. - -Only use these options when there are significant benefits from doing -so. When you specify these options, the assembler and linker -create larger object and executable files and are also slower. -You cannot use @command{gprof} on all systems if you -specify this option, and you may have problems with debugging if -you specify both this option and @option{-g}. +Use these options on systems where the linker can perform optimizations to +improve locality of reference in the instruction space. Most systems using the +ELF object format have linkers with such optimizations. On AIX, the linker +rearranges sections (CSECTs) based on the call graph. The performance impact +varies. + +Together with a linker garbage collection (linker @option{--gc-sections} +option) these options may lead to smaller statically linked executables (after +stripping). + +On ELF/DWARF systems these options do not degenerate the quality of the debug +information. There could be issues with other object files/debug info formats. + +Only use these options when there are significant benefits from doing so. When +you specify these options, the assembler and linker create larger object and +executable files and are also slower. These options affect code generation. +They prevent optimzations by the compiler and assembler using relative +locations inside a translation unit since the locations are unknown until +link-time. An examples for such an optimization is a call to short call +relaxation. @item -fbranch-target-load-optimize @opindex fbranch-target-load-optimize