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| author | Denys Vlasenko | 2018-01-28 20:41:23 +0100 |
|---|---|---|
| committer | Denys Vlasenko | 2018-01-28 20:41:23 +0100 |
| commit | 6f9442ff30f2fa7b66395935b0f59b01ecc89f0e (patch) | |
| tree | 58fcee93b06a807e14a09811f4e04e9c095c8390 | |
| parent | f19e3c1c6c96e3c709ac732ff70c586521f792d3 (diff) | |
| download | busybox-6f9442ff30f2fa7b66395935b0f59b01ecc89f0e.zip busybox-6f9442ff30f2fa7b66395935b0f59b01ecc89f0e.tar.gz | |
ash: make it possible to disable "const global ptr" optimization
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
| -rw-r--r-- | shell/ash.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/shell/ash.c b/shell/ash.c index 6b7386f..4c1b5e4 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -263,6 +263,19 @@ typedef long arith_t; # error "Do not even bother, ash will not run on NOMMU machine" #endif +/* We use a trick to have more optimized code (fewer pointer reloads): + * ash.c: extern struct globals *const ash_ptr_to_globals; + * ash_ptr_hack.c: struct globals *ash_ptr_to_globals; + * This way, compiler in ash.c knows the pointer can not change. + * + * However, this may break on weird arches or toolchains. In this case, + * set "-DBB_GLOBAL_CONST=''" in CONFIG_EXTRA_CFLAGS to disable + * this optimization. + */ +#ifndef BB_GLOBAL_CONST +# define BB_GLOBAL_CONST const +#endif + /* ============ Hash table sizes. Configurable. */ @@ -400,7 +413,7 @@ struct globals_misc { #endif pid_t backgndpid; /* pid of last background process */ }; -extern struct globals_misc *const ash_ptr_to_globals_misc; +extern struct globals_misc *BB_GLOBAL_CONST ash_ptr_to_globals_misc; #define G_misc (*ash_ptr_to_globals_misc) #define exitstatus (G_misc.exitstatus ) #define back_exitstatus (G_misc.back_exitstatus ) @@ -1473,7 +1486,7 @@ struct globals_memstack { size_t g_stacknleft; // = MINSIZE; struct stack_block stackbase; }; -extern struct globals_memstack *const ash_ptr_to_globals_memstack; +extern struct globals_memstack *BB_GLOBAL_CONST ash_ptr_to_globals_memstack; #define G_memstack (*ash_ptr_to_globals_memstack) #define g_stackp (G_memstack.g_stackp ) #define g_stacknxt (G_memstack.g_stacknxt ) @@ -2062,7 +2075,7 @@ struct globals_var { int lineno; char linenovar[sizeof("LINENO=") + sizeof(int)*3]; }; -extern struct globals_var *const ash_ptr_to_globals_var; +extern struct globals_var *BB_GLOBAL_CONST ash_ptr_to_globals_var; #define G_var (*ash_ptr_to_globals_var) #define shellparam (G_var.shellparam ) //#define redirlist (G_var.redirlist ) |