Hi Markus,

On Sun, Sep 4, 2016 at 2:33 PM, SF Markus Elfring
[off-list ref] wrote:

quoted

quoted

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.

…

quoted

quoted

@@ -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;

…

quoted

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.

quoted

but why all the way down here?

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

Does this change improve the resulting binary? I.e. does it make it
smaller or faster? If it's smaller, by how much? if it's faster,
measure it.

Otherwise this change is useless churn - you're making the code more
complicated, longer and harder to read for practically no benefit.

Thanks,

-- 
Julian Calaby

Email: julian.calaby@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/