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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] qemu vs gcc4
Date: Mon, 23 Oct 2006 15:10:45 +0100
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To: Avi Kivity <avi@qumranet.com>
Cc: qemu-devel@nongnu.org

> > That's exactly what my gcc4 hacks do.
> >
> > It gets complicated because a x86 uses variable length insn encodings so
> > you don't know where insn boundaries are, and a jmp instruction is larger
> > than a ret instruction so it's not always possible to do a straight
> > replacement.
>
> how about
>
> void some_generated_instruction(u32 a1, u32 s2)
> {
>        // code
>        asm volatile ( "" );
> }
>
>
> that will force the code to fall through to the null asm code, avoiding
> premature returns.
>
> if the code uses 'return' explicitly, turn it to a goto just before the
> 'asm volatile'.

We already do that. It doesn't stop gcc putting the return in the middle of 
the function.

Paul