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Re: GCC parameter optimisation help
- From: Ian Lance Taylor <iant at google dot com>
- To: vikramsp <vikram2rhyme at gmail dot com>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Tue, 27 Dec 2011 07:15:53 -0800
- Subject: Re: GCC parameter optimisation help
- References: <33037405.post@talk.nabble.com>
vikramsp <vikram2rhyme@gmail.com> writes:
> I've observed that --param name=value type of options are
> having default, min, max values but not all. eg. max-goto-duplication-insns
> has default 8 but max-delay-slot-insn-search has none. My problem is:
>
> 1. Do all parameter have limits and defaults?
They all have defaults, of course. They do not all have limits.
> 2. If yes why they are not documented?
Either because the of a documentation bug or because the default is
obvious. I agree that the default for max-delay-slot-insn-search should
be documented. It is 100.
> 3. If no how to find the best values?
Start by looking at gcc/params.def.
The --param options are generally intended for expert use by people
familiar with how the compiler works. The -f options intended for use
by people not deeply familiar with the compiler. This is not an excuse
for poor documentations, but some of the --param options are quite
difficult to document precisely.
Ian