diff options
Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 1ddd4fe0c3e..4b8bf5939e6 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -333,7 +333,7 @@ Objective-C and Objective-C++ Dialects}. -fsched-stalled-insns=@var{n} -fsched-stalled-insns-dep=@var{n} @gol -fsched2-use-superblocks @gol -fsched2-use-traces -freschedule-modulo-scheduled-loops @gol --fsignaling-nans -fsingle-precision-constant @gol +-fsection-anchors -fsignaling-nans -fsingle-precision-constant @gol -fstack-protector -fstack-protector-all @gol -fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps @gol -funroll-all-loops -funroll-loops -fpeel-loops @gol @@ -5773,6 +5773,35 @@ If a guard check fails, an error message is printed and the program exits. @item -fstack-protector-all Like @option{-fstack-protector} except that all functions are protected. +@item -fsection-anchors +@opindex fsection-anchors +Try to reduce the number of symbolic address calculations by using +shared ``anchor'' symbols to address nearby objects. This transformation +can help to reduce the number of GOT entries and GOT accesses on some +targets. + +For example, the implementation of the following function @code{foo}: + +@smallexample +static int a, b, c; +int foo (void) @{ return a + b + c; @} +@end smallexample + +would usually calculate the addresses of all three variables, but if you +compile it with @option{-fsection-anchors}, it will access the variables +from a common anchor point instead. The effect is similar to the +following pseudocode (which isn't valid C): + +@smallexample +int foo (void) +@{ + register int *xr = &x; + return xr[&a - &x] + xr[&b - &x] + xr[&c - &x]; +@} +@end smallexample + +Not all targets support this option. + @item --param @var{name}=@var{value} @opindex param In some places, GCC uses various constants to control the amount of |
