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Re: [PATCH] final: Improve output for -dp and -fverbose-asm
On Wed, Nov 29, 2017 at 08:46:41PM -0700, Martin Sebor wrote:
> On 11/29/2017 04:13 PM, Segher Boessenkool wrote:
> >This improves the assembler output (for -dp and -fverbose-asm) in
> >several ways. It always prints the insn_cost. It does not print
> >"[length = NN]" but "[c=NN l=NN]", to save space. It does not add one
> >to the instruction alternative number (everything else starts counting
> >those at 0, too). And finally, it tries to keep things lined up in
> >columns a bit better.
> >
> >Tested on powerpc64-linux {-m32,-m64}; is this okay for trunk?
>
> [c=NN l=NN] will be meaningless to those without some deeper
> insight into/experience with what's actually being printed.
> It might as well say [NN NN]. But such extreme terseness would
Length isn't printed on all targets, fwiw.
> seem to run counter to the documented purpose of -fverbose-asm
> to "Put extra commentary information in the generated assembly
> code to make it more readable."
The point is that [length = 12] takes up an awful lot of space. The
output of -fverbose-asm alread suffers from information overload.
> Looking further in the manual I don't see the [length=NN] bit
> mentioned (nor does your patch add a mention of it) so while
> the meaning of [length=NN] isn't exactly obvious, using [l=NN]
> instead certainly won't make it easier to read. Does the manual
> need updating?
Should -fverbose-asm print length (and cost) at all? They should be
printed for -dp (which is for debugging the *compiler*), but are they
very useful for -fverbose-asm (which is primarily for debugging the
*user program*)?
Segher