A patch to offset the rant.

[Denys Vlasenko]

On Sunday 24 October 2010 03:14, Rob Landley wrote:
> I've decided that every time I rant about something on the list, I need to 
> provide a patch to make up for it, so here's an #ifdefectomy for awk.c.

Applied, thanks!

> In gcc 4.3.3, this bloats the code by one byte, and does so in the function 
> "fsrealloc" which I didn't even _touch_.  I boggled at this a bit, and did 
> this little bit of black magic to take a closer look:
> 
>   diff -u <(scripts/showasm busybox_old fsrealloc | cut -b 11-) \
>      <(scripts/showasm busybox_unstripped fsrealloc | cut -b 11-) | less
> 
> For some reason, the optimizer is spilling r13 into a global instead of being 
> able to cache it in edx.  I have NO idea why, looks like a bug in gcc to be 
> honest, and I suspect different gcc versions will behave differently here.
> 
> Possibly the above bit of black magic should become a "scripts/bloatcheckdiff" 
> or similar, with fsrealloc becoming $1 and probably the "cut -b 11-" replaced 
> with something less hackish...

It is already there:

scripts/mkdiff_obj
==================

#!/bin/sh

filter() {
        # sed removes " address: " prefixes which mess up diff
        sed $'s/^\\(\t*\\)[ ]*[0-9a-f][0-9a-f]*:[ \t]*/\\1/' \
        | sed 's/__GI_//g'
}

test -d "$1" || exit 1
test -d "$2" || exit 1

{
        (
                cd "$1" || exit 1
                find -name '*.o' -o -name '*.os' # -o -name '*.so'
        )
        (
                cd "$2" || exit 1
                find -name '*.o' -o -name '*.os' # -o -name '*.so'
        )
} | sed 's:^\./::' | sort | uniq | \
(
IFS=''
while read -r oname; do
        if ! test -f "$1/$oname"; then
                echo "Only $2/$oname"
                continue
        fi
        if ! test -f "$2/$oname"; then
                echo "Only $1/$oname"
                continue
        fi
        diff -q -- "$1/$oname" "$2/$oname" >/dev/null && continue
        (cd "$1"; objdump -dr "$oname" | filter >"$oname.disasm")
        (cd "$2"; objdump -dr "$oname" | filter >"$oname.disasm")
        diff -u "$1/$oname.disasm" "$2/$oname.disasm"
done
)

-- 
vda