From: Dibyendu Majumdar <mobile@majumdar.org.uk>
To: David Malcolm <dmalcolm@redhat.com>
Cc: jit@gcc.gnu.org
Subject: Re: A possible code generation issue
Date: Thu, 01 Jan 2015 00:00:00 -0000 [thread overview]
Message-ID: <CACXZuxceUXP7woZot1gy-ahscx+ime2X-Xi0YXUy7jK=j4wmWg@mail.gmail.com> (raw)
In-Reply-To: <1436046085.24803.35.camel@surprise>
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.
>
> If this is the case it's normally possible to work around it in C by
> rewriting casts using unions.
I guess if you can help me work out which bit of code is causing a
problem then I can implement a fix.
>
> Of course, it could well be a bug at my end.
>
> In any case, I'm not going to be able to have a proper look at this
> until Monday (it's the July 4th holiday weekend here in the US); sorry.
>
No problem - Monday is fine. I have nearly implemented all the Lua
bytecodes that I have working in LLVM only a few left to do.
Regards
Dibyendu
next prev parent reply other threads:[~2015-07-04 22:09 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
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 ` 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 ` 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 ` 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 ` A possible " David Malcolm
2015-01-01 0:00 ` Dibyendu Majumdar [this message]
2015-01-01 0:00 ` Dibyendu Majumdar
2015-01-01 0:00 ` Filed PR jit/66811: jit jumps aren't compilable as C (Re: A possible code generation issue) David Malcolm
2015-01-01 0:00 ` Filed PR jit/66811: jit dumps " 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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