From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] TCG S/390 backend
Date: Tue, 12 May 2009 13:29:42 +0100 [thread overview]
Message-ID: <200905121329.42679.paul@codesourcery.com> (raw)
In-Reply-To: <200905121338.45589.uli@suse.de>
> I found the problem: TCG does not zero- or sign-extend arguments to
> function calls. Unlike, for instance, AMD64, 32-bit arithmetic ops on
> S/390 leave the upper 32 bits of the destination register untouched, so
> there could be any kind of garbage there. If a helper taking a 64-bit
> argument is called with the result of such an operation, stuff breaks.
You mean an helper that takes a 32-bit value, which happens to be passed in a
64-bit register? This is a tricky one because as you say, TCG has no concept
of signed or unsigned values.
I guess we could add some flag bits to the function call for this.
def-helper.h/tcg_gen_callN already has something similar for identifying
64-bit arguments.
Paul
next prev parent reply other threads:[~2009-05-12 12:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-05 12:24 [Qemu-devel] [PATCH] TCG S/390 backend Ulrich Hecht
2009-05-05 18:28 ` malc
2009-05-12 11:38 ` Ulrich Hecht
2009-05-12 12:29 ` Paul Brook [this message]
2009-05-12 12:29 ` malc
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