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Date: Mon, 1 Sep 2008 18:28:16 -0400 (EDT)
From: Vince Weaver <vince@csl.cornell.edu>
Subject: Re: [Qemu-devel] [5123] Fix y register loads and stores
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To: qemu-devel@nongnu.org


> I think something is still odd with the 64-bit multiply code (the rest of the 
> tcg instructions seem to work fine).

I found the problem (this required writing some x86_64 assembly routines 
with pasted in values from out_asm results).

The problem is that my test case does a signed multiply of
    0x386d4380 x 0xc22e4507

These should both be sign extended, but for some reason despite the

     tcg_gen_ext_tl_i64(r_temp, src2);
     tcg_gen_ext_tl_i64(r_temp2, src1);

calls in gen_op_smul() the values aren't sign extended.  This matters for 
the second operand, and thus we get the wrong result.

It wasn't easy to see this with the remote-gdb stuff because annoyingly I 
can't get gdb to display the 64-bit register contents when using 
sparcv8plus binaries.

So something is wrong with the sign extension.  Unfortunately I won't have 
time to look into this more until tomorrow, but I wanted to just get this 
out there.

Vince