Re: [PATCH 7/9] disas/riscv: Provide infrastructure for vendor extensions

[Christoph Müllner]

On Thu, Jun 8, 2023 at 3:05 PM LIU Zhiwei <zhiwei_liu@linux.alibaba.com> wrote:
>
>
> On 2023/5/30 21:18, Christoph Muellner wrote:
> > From: Christoph Müllner <christoph.muellner@vrull.eu>
> >
> > A previous patch provides a pointer to the RISCVCPUConfig data.
> > Let's use this to add the necessary code for vendor extensions.
> > This patch does not change the current behaviour, but clearly
> > defines how vendor extension support can be added to the disassembler.
> >
> > Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
> > ---
> >   disas/riscv.c | 34 ++++++++++++++++++++++++++++++----
> >   1 file changed, 30 insertions(+), 4 deletions(-)
> >
> > diff --git a/disas/riscv.c b/disas/riscv.c
> > index 086edee6a2..db98e3ea6a 100644
> > --- a/disas/riscv.c
> > +++ b/disas/riscv.c
> > @@ -20,6 +20,7 @@
> >   #include "qemu/osdep.h"
> >   #include "disas/dis-asm.h"
> >   #include "disas/riscv.h"
> > +#include "target/riscv/cpu-config.h"
> >
> >   typedef enum {
> >       /* 0 is reserved for rv_op_illegal. */
> > @@ -4599,13 +4600,38 @@ static void decode_inst_decompress(rv_decode *dec, 
> > rv_isa isa)
> >   /* disassemble instruction */
> >
> >   static void
> > -disasm_inst(char *buf, size_t buflen, rv_isa isa, uint64_t pc, rv_inst 
> > inst)
> > +disasm_inst(char *buf, size_t buflen, rv_isa isa, uint64_t pc, rv_inst 
> > inst,
> > +            struct disassemble_info *info)
> >   {
> > +    RISCVCPUConfig *cfg = info->private_data;
> >       rv_decode dec = { 0 };
> >       dec.pc = pc;
> >       dec.inst = inst;
> > -    dec.opcode_data = rvi_opcode_data;
> > -    decode_inst_opcode(&dec, isa);
> > +
> > +    static const struct {
> > +        bool (*guard_func)(const RISCVCPUConfig *);
> > +        const rv_opcode_data *opcode_data;
> > +        void (*decode_func)(rv_decode *, rv_isa);
> > +    } decoders[] = {
> > +        { always_true_p, rvi_opcode_data, decode_inst_opcode },
> > +    };
> > +
> > +    for (size_t i = 0; i < ARRAY_SIZE(decoders); i++) {
> > +        bool (*guard_func)(const RISCVCPUConfig *) = 
> > decoders[i].guard_func;
> > +        const rv_opcode_data *opcode_data = decoders[i].opcode_data;
> > +        void (*decode_func)(rv_decode *, rv_isa) = decoders[i].decode_func;
> > +
> > +        if (guard_func(cfg)) {
> > +            dec.opcode_data = opcode_data;
> > +            decode_func(&dec, isa);
> > +            if (dec.op != rv_op_illegal)
> > +                break;
> > +        }
> > +    }
> > +
> > +    if (dec.op == rv_op_illegal)
> > +        dec.opcode_data = rvi_opcode_data;
>
> Always enclose the if sentence.

Done.

Thanks,
Christoph

>
> Otherwise,
>
> Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
>
> > +
> >       decode_inst_operands(&dec, isa);
> >       decode_inst_decompress(&dec, isa);
> >       decode_inst_lift_pseudo(&dec);
> > @@ -4659,7 +4685,7 @@ print_insn_riscv(bfd_vma memaddr, struct 
> > disassemble_info *info, rv_isa isa)
> >           break;
> >       }
> >
> > -    disasm_inst(buf, sizeof(buf), isa, memaddr, inst);
> > +    disasm_inst(buf, sizeof(buf), isa, memaddr, inst, info);
> >       (*info->fprintf_func)(info->stream, "%s", buf);
> >
> >       return len;