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From: "eggert at gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug other/100735] New: -fno-trampolines doc wrongly implies it affects C, C++ etc.
Date: Mon, 24 May 2021 02:22:54 +0000	[thread overview]
Message-ID: <bug-100735-4@http.gcc.gnu.org/bugzilla/> (raw)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100735

            Bug ID: 100735
           Summary: -fno-trampolines doc wrongly implies it affects C, C++
                    etc.
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eggert at gnu dot org
  Target Milestone: ---

Created attachment 50859
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50859&action=edit
doc patch for -fno-trampolines confusion

The GCC manual's documentation of -fno-trampolines was apparently written from
an Ada point of view. However, when I read it I understandably mistook it to
say that -fno-trampolines also works for C, C++, etc. It doesn't: it is
silently ignored for these languages, and I assume for any language other than
Ada.

This confusion caused me to go in the wrong direction in a Gnulib dicussion, as
I mistakenly thought that entire C apps with nested functions could be compiled
with -fno-trampolines and then use nested C function in stack overflow handlers
where the alternate stack is allocated via malloc. I was wrong, as this won't
work on common platforms like x86-64 where malloc yields non-executable
storage.

A proposed fix for the GCC manual is attached.

             reply	other threads:[~2021-05-24  2:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-24  2:22 eggert at gnu dot org [this message]
2021-05-24 10:24 ` [Bug other/100735] " bruno at clisp dot org
2021-05-25  7:34 ` rguenth at gcc dot gnu.org
2021-05-25  7:42 ` ebotcazou at gcc dot gnu.org
2021-06-09 16:28 ` cvs-commit at gcc dot gnu.org
2021-06-09 18:15 ` law at gcc dot gnu.org
2021-06-09 18:58 ` cvs-commit at gcc dot gnu.org

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