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Re: Shallow copy error in scheduler deps?

From: Jeff Law <law at redhat dot com>
To: Konstantin Vladimirov <konstantin dot vladimirov at gmail dot com>, GCC Development <gcc at gcc dot gnu dot org>
Date: Tue, 20 Oct 2015 09:09:52 -0600
Subject: Re: Shallow copy error in scheduler deps?
Authentication-results: sourceware.org; auth=none
References: <CADn89gRD47V-4n3Mr=c5vjSiOhLLmV5LSASDQ7HgWvB3ZOaf0g at mail dot gmail dot com>

On 10/20/2015 03:43 AM, Konstantin Vladimirov wrote:

Hi,

--- sched-int.h ---

/* Information about the dependency.  */
struct _dep
{
....
   struct dep_replacement *replace;
....
};

typedef dep_def *dep_t;

--- sched-deps.c ---

static void
copy_dep (dep_t to, dep_t from)
{
   memcpy (to, from, sizeof (*to)); // oops?
}

This might be source of double free problems, etc. I can not build
exact reproduction for x86 or arm, but I stepped on it in scheduler
code for private backend. Is it worth filing as a bug, or is it part
of design?

I don't think it's by design. It'll certainly help if you canthoroughly describe the path by which you get the double-free.

Conceptually I agree with you, but I'd have to sit down with a debuggerto really be sure.


Jeff

References:
- Shallow copy error in scheduler deps?
  - From: Konstantin Vladimirov

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