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Re: VTA merge - cmdline

Hi, Mark,

On Jun  7, 2009, Mark Mitchell <> wrote:

> --param should be used for tuning parameters for the compiler, i.e.,
> where we would otherwise be tempted to use "magic constants".

Thanks for providing a definition of what â--paramâ is supposed to stand
for.  It was quite convincing to me, so I started changing
-fmin-insn-uid to --param.  When the time came to document it under
--param, I found yet another definition, that actually matched my
understanding of the purpose of --param.

I wonder whether there's a misunderstanding as to the meaning of the new
proposed flag, or whether the manual no longer reflects the expected use
of --params.

--param is documented under âOptimization optionsâ as âconstants to
control the amount of optimization that is doneâ.

It doesn't make sense for min-insn-uid=N to be documented as such.

min-insn-uid=N is supposed to bump up the range of INSN_UIDs used by
non-debug insns, so that they start at N, while debug insns take up the
range 1..N-1.

This makes it easier to compare compiler dumps in VTA and non-VTA
compiles.  It is not supposed to have any effect on optimization.
Whatever effects it had before were already fixed.

It is not an optimization parameter.  It is a dump option, very much
along the lines of -fdump-noaddr, -fdump-unnumbered,
-fdump-unnumbered-links.  It just so happens that it takes a number as
an argument, like the other dump option -fsched-verbose.

If --param is to be used for things other than constants to control the
amount of optimization, its documentation must adjusted to reflect this,
and moved where it belongs.

What now?

Alexandre Oliva, freedom fighter
You must be the change you wish to see in the world. -- Gandhi
Be Free! --   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer

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