Re: [PATCH v7 44/64] target/nios2: Split out helpers for gen_* translate macros

[Peter Maydell]

On Thu, 21 Apr 2022 at 16:55, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Do as little work as possible within the macros.
> Split out helper functions and pass in arguments instead.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/nios2/translate.c | 215 +++++++++++++++++++++++++--------------
>  1 file changed, 141 insertions(+), 74 deletions(-)
>
> diff --git a/target/nios2/translate.c b/target/nios2/translate.c
> index a3c63dbbbd..74672101ca 100644
> --- a/target/nios2/translate.c
> +++ b/target/nios2/translate.c
> @@ -71,6 +71,21 @@ typedef struct {
>          .a     = extract32((code), 27, 5), \
>      }
>
> +static target_ulong imm_unsigned(const InstrIType *i)
> +{
> +    return i->imm16.u;
> +}
> +
> +static target_ulong imm_signed(const InstrIType *i)
> +{
> +    return i->imm16.s;
> +}
> +
> +static target_ulong imm_shifted(const InstrIType *i)
> +{
> +    return i->imm16.u << 16;
> +}
> +
>  /* R-Type instruction parsing */
>  typedef struct {
>      uint8_t op;
> @@ -268,40 +283,62 @@ static void gen_bxx(DisasContext *dc, uint32_t code, 
> uint32_t flags)
>  }
>
>  /* Comparison instructions */
> -#define gen_i_cmpxx(fname, op3)                                              
> \
> -static void (fname)(DisasContext *dc, uint32_t code, uint32_t flags)         
> \
> -{                                                                            
> \
> -    I_TYPE(instr, (code));                                                   
> \
> -    tcg_gen_setcondi_tl(flags, cpu_R[instr.b], cpu_R[instr.a], (op3));       
> \
> +static void do_i_cmpxx(DisasContext *dc, uint32_t insn, TCGCond cond,
> +                       target_ulong (*imm)(const InstrIType *))

Can we have some typedefs if we're passing function pointers around,
please? I think they're easier to read than having raw
function-pointer type signatures in function prototypes.

> +{
> +    I_TYPE(instr, insn);
> +
> +    if (likely(instr.b != R_ZERO)) {
> +        tcg_gen_setcondi_tl(cond, cpu_R[instr.b],
> +                            load_gpr(dc, instr.a), imm(&instr));
> +    }

The old code didn't do this check against R_ZERO.

>  }

>  /* Math/logic instructions */
> -#define gen_r_math_logic(fname, insn, op3)                                 \
> -static void (fname)(DisasContext *dc, uint32_t code, uint32_t flags)       \
> -{                                                                          \
> -    R_TYPE(instr, (code));                                                 \
> -    if (likely(instr.c != R_ZERO)) {                                       \
> -        tcg_gen_##insn(cpu_R[instr.c], load_gpr((dc), instr.a), (op3));    \
> -    }                                                                      \
> +static void do_ri_math_logic(DisasContext *dc, uint32_t insn,
> +                             void (*fn)(TCGv, TCGv, int32_t))
> +{
> +    R_TYPE(instr, insn);
> +
> +    if (likely(instr.c != R_ZERO)) {
> +        fn(cpu_R[instr.c], load_gpr(dc, instr.a), instr.imm5);
> +    }
>  }
>
> -gen_r_math_logic(add,  add_tl,   load_gpr(dc, instr.b))
> -gen_r_math_logic(sub,  sub_tl,   load_gpr(dc, instr.b))
> -gen_r_math_logic(mul,  mul_tl,   load_gpr(dc, instr.b))
> +static void do_rr_math_logic(DisasContext *dc, uint32_t insn,
> +                             void (*fn)(TCGv, TCGv, TCGv))
> +{
> +    R_TYPE(instr, insn);
>
> -gen_r_math_logic(and,  and_tl,   load_gpr(dc, instr.b))
> -gen_r_math_logic(or,   or_tl,    load_gpr(dc, instr.b))
> -gen_r_math_logic(xor,  xor_tl,   load_gpr(dc, instr.b))
> -gen_r_math_logic(nor,  nor_tl,   load_gpr(dc, instr.b))
> -
> -gen_r_math_logic(srai, sari_tl,  instr.imm5)
> -gen_r_math_logic(srli, shri_tl,  instr.imm5)
> -gen_r_math_logic(slli, shli_tl,  instr.imm5)
> -gen_r_math_logic(roli, rotli_tl, instr.imm5)
> -
> -#define gen_r_mul(fname, insn)                                         \
> -static void (fname)(DisasContext *dc, uint32_t code, uint32_t flags)   \
> -{                                                                      \
> -    R_TYPE(instr, (code));                                             \
> -    if (likely(instr.c != R_ZERO)) {                                   \
> -        TCGv t0 = tcg_temp_new();                                      \
> -        tcg_gen_##insn(t0, cpu_R[instr.c],                             \
> -                       load_gpr(dc, instr.a), load_gpr(dc, instr.b));  \
> -        tcg_temp_free(t0);                                             \
> -    }                                                                  \
> +    if (likely(instr.c != R_ZERO)) {
> +        fn(cpu_R[instr.c], load_gpr(dc, instr.a), load_gpr(dc, instr.b));
> +    }
>  }
>
> -gen_r_mul(mulxss, muls2_tl)
> -gen_r_mul(mulxuu, mulu2_tl)
> -gen_r_mul(mulxsu, mulsu2_tl)
> +#define gen_ri_math_logic(fname, insn)                                      \
> +    static void (fname)(DisasContext *dc, uint32_t code, uint32_t flags)    \
> +    { do_ri_math_logic(dc, code, tcg_gen_##insn##_tl); }
>
> -#define gen_r_shift_s(fname, insn)                                         \
> -static void (fname)(DisasContext *dc, uint32_t code, uint32_t flags)       \
> -{                                                                          \
> -    R_TYPE(instr, (code));                                                 \
> -    if (likely(instr.c != R_ZERO)) {                                       \
> -        TCGv t0 = tcg_temp_new();                                          \
> -        tcg_gen_andi_tl(t0, load_gpr((dc), instr.b), 31);                  \
> -        tcg_gen_##insn(cpu_R[instr.c], load_gpr((dc), instr.a), t0);       \
> -        tcg_temp_free(t0);                                                 \
> -    }                                                                      \
> +#define gen_rr_math_logic(fname, insn)                                      \
> +    static void (fname)(DisasContext *dc, uint32_t code, uint32_t flags)    \
> +    { do_rr_math_logic(dc, code, tcg_gen_##insn##_tl); }


git diff has made a bit of a pig's ear of this, interleaving the
changes related to math_logic and the ones related to shift and mul.
If you do these changes one insn group at a time rather than
all in one patch I think the resulting diff should be easier to read.

-- PMM