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Re: [PATCH] final: Improve output for -dp and -fverbose-asm
On Thu, Nov 30, 2017 at 09:54:26AM -0700, Martin Sebor wrote:
> >It is neither line length nor amt of info that makes the second one
> >way better readable.
>
> The justification certainly makes it easier to read. But
> the abbreviations make it harder to interpret. [c=4 l=4]
> makes no sense to anyone not already familiar with what
> it means.
>
> There's nothing wrong with using mnemonics as long as they're
> well established and commonly understood. Absent that, they
> should be explained in some accessible document.
>
> Not everyone who reads the verbose assembly is familiar with
> GCC internals. Users read it to help debug problems in their
> code. They shouldn't have to also study GCC source code to
> understand what the contents mean.
This is the -dp output, I hardly ever use -fverbose-asm, it has been
unreadable for ten years or so.
-fverbose-asm looks like this:
===
.L.yk:
# 81288.c:4: unsigned int *un = (f3 != 0) ? &t4 : 0;
cmpdi 0,4,0 # tmp130, f3
beq 0,.L2 #
# 81288.c:6: *un ^= t4;
srdi 9,3,32 #, tmp131, t4
xor 9,9,3 #, tmp132, tmp131, t4
# 81288.c:7: if (*un == t4)
rldicl 9,9,0,32 # tmp133, tmp132
# 81288.c:7: if (*un == t4)
cmpd 7,9,3 # t4, tmp134, tmp133
beq 7,.L7 #
.L5:
# 81288.c:11: }
mr 3,4 #, <retval>
blr
.L2:
# 81288.c:6: *un ^= t4;
lwz 9,0(4) # MEM[(unsigned int *)0B], _13
trap
.L7:
# 81288.c:8: f3 = !!t4;
addic 4,9,-1 # tmp139, tmp133
subfe 4,4,9 # <retval>, tmp139, tmp133
b .L5 #
===
If we're okay with outputting that kind of stuff to *users*, then how
bad is [c=8 l=4] for GCC developers? Heh.
Segher