Re: [PATCH 2/4] sparc: bpf_jit: Move four assignments in bpf_jit_compile()

SF Markus Elfring
2016-09-04T04:34:52Z

>> Date: Sat, 3 Sep 2016 17:45:28 +0200
>>
>> Move the assignments for four local variables a bit at the beginning
>> so that they will only be performed if a corresponding memory allocation
>> succeeded by this function.
…
>> @@ -362,10 +362,10 @@ do { *prog++ = BR_OPC | WDISP22(OFF); \
>>
>> void bpf_jit_compile(struct bpf_prog *fp)
>> {
>> - unsigned int cleanup_addr, proglen, oldproglen = 0;
>> - u32 temp[8], *prog, *func, seen = 0, pass;
>> - const struct sock_filter *filter = fp->insns;
>> - int i, flen = fp->len, pc_ret0 = -1;
>> + unsigned int cleanup_addr, proglen, oldproglen;
>> + u32 temp[8], *prog, *func, seen, pass;
>> + const struct sock_filter *filter;
>> + int i, flen = fp->len, pc_ret0;
>> unsigned int *addrs;
>> void *image;
>>
>> @@ -385,6 +385,10 @@ void bpf_jit_compile(struct bpf_prog *fp)
>> }
>> cleanup_addr = proglen; /* epilogue address */
>> image = NULL;
>> + filter = fp->insns;
>> + oldproglen = 0;
>> + pc_ret0 = -1;
>> + seen = 0;
>> for (pass = 0; pass < 10; pass++) {
>> u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
…
> If you were moving the assignments on declaration onto separate lines
> at the top of the file then ok,

I see another software design option where the transformation result might be looking
more pleasing for you again.

> but why all the way down here?

* How do you think about the reason I gave in the short commit message?

* Are you interested in an other software refactoring instead?
http://refactoring.com/catalog/reduceScopeOfVariable.html

Would you eventually like to move the source code for this for loop into another function?
http://refactoring.com/catalog/extractMethod.html

Regards,
Markus