6f9442ff3
Denys Vlasenko
2018-01-28
Subject
ash: make it possible to disable "const global ptr" optimization
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Commit Diff GitHub →
shell/ash.c+16 -3
| @@ -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 ) | |