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ash: make it possible to disable "const global ptr" optimization

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-01-28 20:41:23 +01:00
parent f19e3c1c6c
commit 6f9442ff30
1 changed files with 16 additions and 3 deletions
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19
shell/ash.c
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@ -263,6 +263,19 @@ typedef long arith_t;
# error "Do not even bother, ash will not run on NOMMU machine" # error "Do not even bother, ash will not run on NOMMU machine"
#endif #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. */ /* ============ Hash table sizes. Configurable. */
@ -400,7 +413,7 @@ struct globals_misc {
#endif #endif
pid_t backgndpid; /* pid of last background process */ 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 G_misc (*ash_ptr_to_globals_misc)
#define exitstatus (G_misc.exitstatus ) #define exitstatus (G_misc.exitstatus )
#define back_exitstatus (G_misc.back_exitstatus ) #define back_exitstatus (G_misc.back_exitstatus )
@ -1473,7 +1486,7 @@ struct globals_memstack {
size_t g_stacknleft; // = MINSIZE; size_t g_stacknleft; // = MINSIZE;
struct stack_block stackbase; 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_memstack (*ash_ptr_to_globals_memstack)
#define g_stackp (G_memstack.g_stackp ) #define g_stackp (G_memstack.g_stackp )
#define g_stacknxt (G_memstack.g_stacknxt ) #define g_stacknxt (G_memstack.g_stacknxt )
@ -2062,7 +2075,7 @@ struct globals_var {
int lineno; int lineno;
char linenovar[sizeof("LINENO=") + sizeof(int)*3]; 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 G_var (*ash_ptr_to_globals_var)
#define shellparam (G_var.shellparam ) #define shellparam (G_var.shellparam )
//#define redirlist (G_var.redirlist ) //#define redirlist (G_var.redirlist )