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invoke.texi: Document -fdelete-null-pointer-checks 

* invoke.texi: Document -fdelete-null-pointer-checks
        * toplev.c (flag_delete_null_pointer_checks): New.
        (f_options): Add entry for -fdelete-null-pointer-checks.
        (rest_of_compilation): Conditionalize null pointer check
        elimination on flag_delete_null_pointer_checks.
        (main): If -O2 or greater, enable -fdelete-null-pointer-checks

From-SVN: r29631
This commit is contained in:
Jeffrey A Law 1999-09-23 19:57:50 +00:00 committed by Jeff Law
parent 0cffaca32c
commit b6d24183df
3 changed files with 28 additions and 3 deletions
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9
gcc/ChangeLog
View File

@ -1,3 +1,12 @@
Thu Sep 23 13:55:21 1999 Jeffrey A Law (law@cygnus.com)
* invoke.texi: Document -fdelete-null-pointer-checks
* toplev.c (flag_delete_null_pointer_checks): New.
(f_options): Add entry for -fdelete-null-pointer-checks.
(rest_of_compilation): Conditionalize null pointer check
elimination on flag_delete_null_pointer_checks.
(main): If -O2 or greater, enable -fdelete-null-pointer-checks
1999-09-23 10:56 -0700 Zack Weinberg <zack@bitmover.com>
* iso646.h, stdarg.h, stdbool.h, stddef.h, varargs.h: Add

10
gcc/invoke.texi
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@ -153,7 +153,7 @@ in the following sections.
-falign-functions=@var{n} -falign-labels=@var{n} -falign-loops=@var{n}
-falign-jumps=@var{n} -fbranch-probabilities
-fcaller-saves -fcse-follow-jumps -fcse-skip-blocks
-fdelayed-branch -fexpensive-optimizations
-fdelayed-branch -fdelete-null-pointer-checks -fexpensive-optimizations
-ffast-math -ffloat-store -fforce-addr -fforce-mem -fno-math-errno
-fdata-sections -ffunction-sections -fgcse
-finline-functions -finline-limit=@var{n} -fkeep-inline-functions
@ -2459,6 +2459,14 @@ Run the loop optimizer twice.
Perform a global common subexpression elimination pass.
This pass also performs global constant and copy propagation.
@item -fdelete-null-pointer-checks
Use global dataflow analysis to identify and eliminate useless null
pointer checks. Programs which rely on NULL pointer dereferences @emph{not}
halting the program may not work properly with this option. Use
-fno-delete-null-pointer-checks to disable this optimizing for programs
which depend on that behavior.
@item -fexpensive-optimizations
Perform a number of minor optimizations that are relatively expensive.

12
gcc/toplev.c
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@ -568,6 +568,11 @@ int flag_syntax_only = 0;
static int flag_gcse;
/* Nonzero means to use global dataflow analysis to eliminate
useless null pointer tests. */
static int flag_delete_null_pointer_checks;
/* Nonzero means to rerun cse after loop optimization. This increases
compilation time about 20% and picks up a few more common expressions. */
@ -894,6 +899,8 @@ lang_independent_options f_options[] =
"Run CSE pass after loop optimisations"},
{"rerun-loop-opt", &flag_rerun_loop_opt, 1,
"Run the loop optimiser twice"},
{"delete-null-pointer-checks", &flag_delete_null_pointer_checks, 1,
"Delete useless null pointer checks" },
{"pretend-float", &flag_pretend_float, 1,
"Pretend that host and target use the same FP format"},
{"schedule-insns", &flag_schedule_insns, 1,
@ -3707,7 +3714,7 @@ rest_of_compilation (decl)
goto exit_rest_of_compilation;
/* Try to identify useless null pointer tests and delete them. */
if (optimize > 1)
if (flag_delete_null_pointer_checks)
TIMEVAR (jump_time, delete_null_pointer_checks (get_insns ()));
/* Dump rtl code after jump, if we are doing that. */
@ -3746,7 +3753,7 @@ rest_of_compilation (decl)
!JUMP_AFTER_REGSCAN));
/* Try to identify useless null pointer tests and delete them. */
if (optimize > 1)
if (flag_delete_null_pointer_checks)
TIMEVAR (jump_time, delete_null_pointer_checks (get_insns ()));
/* Dump rtl code after cse, if we are doing that. */
@ -5322,6 +5329,7 @@ main (argc, argv)
#endif
flag_regmove = 1;
flag_strict_aliasing = 1;
flag_delete_null_pointer_checks = 1;
}
if (optimize >= 3)