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Re: Probably inaccuracy in GCC 4.7.0 documentation.
- From: Gerald Pfeifer <gerald at pfeifer dot com>
- To: Роман Саженков <r-o-m-m-y at yandex dot ru>
- Cc: gcc at gcc dot gnu dot org
- Date: Wed, 8 Apr 2015 20:43:31 +0200 (CEST)
- Subject: Re: Probably inaccuracy in GCC 4.7.0 documentation.
- Authentication-results: sourceware.org; auth=none
- References: <517191337153839 at web21d dot yandex dot ru>
On Wed, 16 May 2012, Роман Саженков wrote:
> It seems like I've found an inaccuracy in GCC 4.7.0 documentation. It is
> about -fdefer-pop optimization option. The point is that this option is
> mentioned in the list of optimization flags which -O1 turns on (Chapter
> 3: GCC Command Options, part 3.10 Options That Control Optimization,
> page 107/766 of http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc.pdf), but
> there are no any other allusions to -fdefer-pop in the document, even in
> 3.1 Option Summary, where it is expected to be. There is no explanation
> of what this flag does in HTML version of the document too (here
> and here
> I'm guessing that this flag is not further supported by GCC, or not yet
thank you for reporting this, and sorry for getting back to you
with nearly three years delay.
You did find a real issue in that -fdefer-pop is listed as being
activated by the -O option, but not anywhere else in the documentation.
However, there is actually code to support this option, specifically
in gcc/common.opt and gcc/calls.c:
calls.c: else if (flag_defer_pop && inhibit_defer_pop == 0
common.opt: Common Report Var(flag_defer_pop) Optimization
I filed a bug report to track this, and hopefully one of the
technical experts is going to address it: