Save 8 bytes in __{read,write}_lock_failed...
PATCH 1/1 Save 8 bytes in __{read,write}_lock_failed...
Hi,
recent bugreport from Chris Rankin pointed out to me
that last jump in both __read_lock_failed and __write_lock_failed uses 4 byte offset, although 1 byte is enough. It happens because of __write_lock_failed is .globl, and so gas emits 4 byte offset + R_386_PC32 relocation (should it? I always thought that only .weak symbols may be overwritten from other file).
Simple patch below makes SMP kernel 8 bytes shorter.
Best regards,
Petr Vandrovec [email protected]
arch/i386/kernel/semaphore.c +4 -2
@@ -275,12 +275,13 @@".align 4\n" ".globl __write_lock_failed\n" "__write_lock_failed:\n\t" +"0:\n\t" LOCK "addl $" RW_LOCK_BIAS_STR ",(%eax)\n" "1: rep; nop\n\t" "cmpl $" RW_LOCK_BIAS_STR ",(%eax)\n\t" "jne 1b\n\t" LOCK "subl $" RW_LOCK_BIAS_STR ",(%eax)\n\t" -"jnz __write_lock_failed\n\t" +"jnz 0b\n\t" "ret" );
@@ -289,12 +290,13 @@".align 4\n" ".globl __read_lock_failed\n" "__read_lock_failed:\n\t" +"0:\n\t" LOCK "incl (%eax)\n" "1: rep; nop\n\t" "cmpl $1,(%eax)\n\t" "js 1b\n\t" LOCK "decl (%eax)\n\t" -"js __read_lock_failed\n\t" +"js 0b\n\t" "ret" );#endif