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Re: [Qemu-devel] Bug in PPC TCG for rlwimi ?

From: Peter Maydell
Subject: Re: [Qemu-devel] Bug in PPC TCG for rlwimi ?
Date: Tue, 13 May 2014 22:09:07 +0100

On 13 May 2014 21:56, Tom Musta <address@hidden> wrote:
> I am chasing a bug in ppc64-linux-user when hosted on PPC 64.
> I believe I have narrowed the problem to QEMU's emulation of an rlwimi 
> instruction
> in ld64.so.  The in/out asm and register dump are below.  And so is the ppc 
> translation source.
> The inbound contents of r4 is 0x24.  The expected value of r4 after "rlwimi 
> r4,r4,8,16,23"
> is 0x2424 but is zero.  What looks strange to me in the out_asm is the "lwz 
> r14,32(r27)"
> instruction, which appears to be generated from the 
> "tcg_gen_trun_i64_i32(t2,cpu_gpr[rS(ctx->opcode)])"
> statement.  If it is going to load only 4 bytes, shouldn't it be at offset 
> 32+4 ?

Is the host big or little endian PPC? Offset 32 is right for little-endian...

> I have not yet been able to connect the dots between the QEMU source and the 
> emitted (TCG)
> code.

Dumping the TCG opcodes would probably help here (-d op)...

-- PMM

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