Feedback requested on using #defines to improve the performance of the TSRMG macro

When compiled for multi-threaded (#ifdef ZTS ) operation, the various subsystems in PHP use dynamically allocated (ts_allocate_id) identifiers to index into the thread-local storage for each subsystem. These dynamically allocated ids are used by macros such as CG, EG, PG, AG. The TSRMG macro is defined as: #define TSRMG(id, type, element) (((type) (*((void ***) tsrm_ls))[TSRM_UNSHUFFLE_RSRC_ID(id)])->element) The PG macro is defined as: # define PG(v) TSRMG(core_globals_id, php_core_globals *, v) where core_globals_id is extern PHPAPI int core_globals_id; cc -E of PG(connection_status) = PHP_CONNECTION_ABORTED; translates to: (((php_core_globals *) (*((void ***) tsrm_ls))[((core_globals_id)-1)])->connection_status) = 1; and cc -S of the same code results in: .loc 1 108 0 movl %ebx, %eax subl core_globals_id, %eax movl (%esi), %edx sall $2, %eax negl %eax movl (%edx,%eax), %eax movw $1, 144(%eax) I used fixed IDs instead of dynamically allocated ones and noticed a decent improvement in performance (few percentage points) when running a web-based ecommerce-site workload on SPARC CMT hardware. With my changes the PG macro is defined as: # define PG(v) TSRMG(CORE_GLOBALS_ID, php_core_globals *, v) #define CORE_GLOBALS_ID 10 and core_globals_id is extern PHPAPI const ts_rsrc_id core_globals_id; cc -E of the same line of code translates to: (((php_core_globals *) (*((void ***) tsrm_ls))[((10)-1)])->connection_status) = 1; cc -S (my version): .loc 1 108 0 movl (%eax), %eax movl 36(%eax), %eax movw $1, 144(%eax) The patch is fairly long, so rather than attach it to this email, i'll point to it. It'd be great if someone could give me feedback on my changes - http://bitbucket.org/arvi/arviq/src/tip/arvi-16-ts_allocate_reserved_id - for using reserved/fixed IDs for accessing thread-local storage of frequently used/known/core subsystems. I think the changes only affect the #ifdef ZTS codepaths. Thanks, Arvi