Re: [RFC PATCH v3 25/34] Hexagon (target/hexagon) macros to interface with the generator

[Richard Henderson]

On 8/30/20 1:30 PM, Taylor Simpson wrote:
> 
> 
>> -----Original Message-----
>> From: Richard Henderson <richard.henderson@linaro.org>
>> Sent: Friday, August 28, 2020 6:49 PM
>> To: Taylor Simpson <tsimpson@quicinc.com>; qemu-devel@nongnu.org
>> Cc: philmd@redhat.com; laurent@vivier.eu; riku.voipio@iki.fi;
>> aleksandar.m.mail@gmail.com; ale@rev.ng
>> Subject: Re: [RFC PATCH v3 25/34] Hexagon (target/hexagon) macros to
>> interface with the generator
>>
>> On 8/18/20 8:50 AM, Taylor Simpson wrote:
>>> +#define DECL_REG(NAME, NUM, X, OFF) \
>>> +    TCGv NAME = tcg_temp_local_new(); \
>>> +    int NUM = REGNO(X) + OFF
>>> +
>>> +#define DECL_REG_WRITABLE(NAME, NUM, X, OFF) \
>>> +    TCGv NAME = tcg_temp_local_new(); \
>>> +    int NUM = REGNO(X) + OFF; \
>>> +    do { \
>>> +        int is_predicated = GET_ATTRIB(insn->opcode, A_CONDEXEC); \
>>> +        if (is_predicated && !is_preloaded(ctx, NUM)) { \
>>> +            tcg_gen_mov_tl(hex_new_value[NUM], hex_gpr[NUM]); \
>>> +        } \
>>> +    } while (0)
>>> +/*
>>> + * For read-only temps, avoid allocating and freeing
>>> + */
>>> +#define DECL_REG_READONLY(NAME, NUM, X, OFF) \
>>> +    TCGv NAME; \
>>> +    int NUM = REGNO(X) + OFF
>>> +
>>> +#define DECL_RREG_d(NAME, NUM, X, OFF) \
>>> +    DECL_REG_WRITABLE(NAME, NUM, X, OFF)
>>> +#define DECL_RREG_e(NAME, NUM, X, OFF) \
>>> +    DECL_REG(NAME, NUM, X, OFF)
>>
>> Is there a good reason for all these macros?
>> Why not just bake this knowledge into gen_tcg_funcs.py?
>> Seems like it would be just a couple of functions...
>>
>> At present, both this and the intermediary files are unreadable.  One has to
>> pass genptr.c through -E and indent to see what's going on.
> 
> I add the regid...

No, that doesn't answer the question.

Why does DECL_RREG_d et al exist as macros at all?  Why not emit the expansions
directly by gen_tcg_funcs.py?

It seems to me that all this does is obfuscate the code, adding one more layer
that one has to unwind in order to understand.


r~