From: David Malcolm <dmalcolm@redhat.com>
To: Dibyendu Majumdar <mobile@majumdar.org.uk>
Cc: jit@gcc.gnu.org
Subject: Filed PR jit/66811: jit jumps aren't compilable as C (Re: A possible code generation issue)
Date: Thu, 01 Jan 2015 00:00:00 -0000 [thread overview]
Message-ID: <1436364950.24803.63.camel@surprise> (raw)
In-Reply-To: <CACXZuxfP_huMs8OFkutm7affRiRV7YK4vWZ1yBt5SMCp+hB8UQ@mail.gmail.com>
On Mon, 2015-07-06 at 22:29 +0100, Dibyendu Majumdar wrote:
> On 4 July 2015 at 23:09, Dibyendu Majumdar <mobile@majumdar.org.uk> wrote:
> > On 4 July 2015 at 22:41, David Malcolm <dmalcolm@redhat.com> wrote:
> >>> Adding the -fno-strict-aliasing appears to resolve the issue with -O2
> >>> and -O3 but with this enabled the benchmarks are degraded.
> >>
> >> If "-fno-strict-aliasing" resolved this, then that suggests that there
> >> are various casts in the code that if this were C would take us into
> >> "undefined behavior" territory, and the optimizer is trying a little too
> >> hard. This isn't C, but similar rules apply. If that's what this is,
> >> then this is at least a documentation issue with libgccjit; we need to
> >> document what the rules are.
> >>
> >>
> >> Of course, it could well be a bug at my end.
> >>
>
> Dave,
>
> Attached is a hacked version in C of the dump from the code. I thought
> it might be useful to generate code directly using gcc -O3 -S on this
> file - from what I can tell the generated code looks different from
> what I am getting in libgccjit.
>
> BTW the dump of types is problematic in many ways:
> 1) types are in wrong order
> 2) function types are incorrectly output
> 3) array types are incorrectly output
> 4) in one case as least a pointer was missing.
>
> It would be useful if the generated dump was correct C so that it can
> directly compiled in gcc.
Agreed. I've filed this as an RFE for the jit as:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66811
next prev parent reply other threads:[~2015-07-08 14:23 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-01 0:00 A possible code generation issue Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Filed PR jit/66812 for the " David Malcolm
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` [PATCH] PR jit/66812: Candidate fix for for the code generation issue, v1 David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Filed PR jit/66812 for the code generation issue Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` A possible " David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` David Malcolm [this message]
2015-01-01 0:00 ` Filed PR jit/66811: jit dumps aren't compilable as C (Re: A possible code generation issue) David Malcolm
2015-01-01 0:00 ` A possible code generation issue Dibyendu Majumdar
2015-01-01 0:00 ` PR jit/66783 (Re: A possible code generation issue) David Malcolm
2015-01-01 0:00 ` [PATCH, committed] PR jit/66783: prevent use of opaque structs David Malcolm
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