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Date: Thu, 15 May 2003 13:05:41 -0700 (PDT)
Message-Id: <20030515.130541.41655467.davem@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] Updated Sparc support
From: "David S. Miller" <davem@redhat.com>
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To: qemu-devel@nongnu.org, jrydberg@night.trouble.net

   From: Johan Rydberg <jrydberg@night.trouble.net>
   Date: Thu, 15 May 2003 15:03:33 +0200

   Do you still use the register windows, or does GCC generate code without
   save/restore?  Is this possible, really?
   
I used register windows.

Making GCC generate non-register windowed code using -mflat is
unusable because due to a bug it does not respect the
-fno-delayed-branch option when in that mode.

   The reason for me asking is that I some time soon "port" my simulator 
   [1] to SPARC hosts, and it needs to have a lot of global registers
   (more than those 6-7 available).
   
Just only execute the generated code in a fixed context and thus
in the same register window, then at the call site into the generated
code clobber all of the input registers.

Just look at the qemu code, it works quite well.

   Is the fixed flags really needed or is it just because the global
   register definitions is made in op-i386.c (or whatever) ?
   
You really do need this, because you cannot guarentee that every
source file will see the global register declarations in exec-i386.h