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Re: [Qemu-devel] [PATCH 4/7] tcg/mips: Support r6 JR encoding
From: |
James Hogan |
Subject: |
Re: [Qemu-devel] [PATCH 4/7] tcg/mips: Support r6 JR encoding |
Date: |
Wed, 30 Sep 2015 22:24:10 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
Hi Richard,
On Thu, Oct 01, 2015 at 06:49:11AM +1000, Richard Henderson wrote:
> On 10/01/2015 01:30 AM, James Hogan wrote:
> > MIPSr6 encodes JR as JALR with zero as the link register, and the pre-r6
> > JR encoding is removed. Update TCG to use the new encoding when built
> > for r6.
> >
> > We still use the old encoding for pre-r6, so as not to confuse return
> > prediction stack hardware which may detect only particular encodings of
> > the return instruction.
> >
> > Signed-off-by: James Hogan <address@hidden>
> > Cc: Richard Henderson <address@hidden>
> > Cc: Aurelien Jarno <address@hidden>
> > ---
> > tcg/mips/tcg-target.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/tcg/mips/tcg-target.c b/tcg/mips/tcg-target.c
> > index 4305af967326..0a16140b1cdb 100644
> > --- a/tcg/mips/tcg-target.c
> > +++ b/tcg/mips/tcg-target.c
> > @@ -288,7 +288,7 @@ typedef enum {
> > OPC_SRLV = OPC_SPECIAL | 0x06,
> > OPC_ROTRV = OPC_SPECIAL | (0x01 << 6) | 0x06,
> > OPC_SRAV = OPC_SPECIAL | 0x07,
> > - OPC_JR = OPC_SPECIAL | 0x08,
> > + OPC_JR_R5 = OPC_SPECIAL | 0x08,
> > OPC_JALR = OPC_SPECIAL | 0x09,
> > OPC_MOVZ = OPC_SPECIAL | 0x0A,
> > OPC_MOVN = OPC_SPECIAL | 0x0B,
> > @@ -322,6 +322,9 @@ typedef enum {
> > OPC_SEH = OPC_SPECIAL3 | 0x620,
> > } MIPSInsn;
> >
> > +/* MIPS r6 doesn't have JR, JALR should be used instead */
> > +#define OPC_JR (use_mips32r6_instructions ? OPC_JALR : OPC_JR_R5)
>
> This could be done in the enum instead of a define, but otherwise,
True, I'll do that.
Thanks
James
>
>
> Reviewed-by: Richard Henderson <address@hidden>
>
>
> r~
>
>
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Description: Digital signature
- [Qemu-devel] [PATCH 0/7] tcg/mips: Minimal R6 support, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 7/7] tcg/mips: Support r6 SEL{NE, EQ}Z instead of MOVN/MOVZ, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 3/7] tcg/mips: Add use_mips32r6_instructions definition, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 2/7] disas/mips: Add R6 jr/jr.hb to disassembler, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 5/7] tcg/mips: Support r6 multiply/divide encodings, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 4/7] tcg/mips: Support r6 JR encoding, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 6/7] tcg/mips: Support full movcond select operation, James Hogan, 2015/10/08
- [Qemu-devel] [PATCH 1/7] tcg-opc.h: Simplify debug_insn_start def, James Hogan, 2015/10/08