RE: [RFC PATCH v3 30/34] Hexagon (target/hexagon) TCG for instructions with multiple definitions

[Taylor Simpson]

> > On 8/31/20 4:10 PM, Taylor Simpson wrote:
> > >
> > >
> > >> -----Original Message-----
> > >> From: Richard Henderson <richard.henderson@linaro.org>
> > >> Sent: Monday, August 31, 2020 1:20 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 30/34] Hexagon (target/hexagon) TCG for
> > >> instructions with multiple definitions
> > >>
> > Ho hum.  Maybe I'm trying to overthink this too much before tackling the
> > ultimate goal of full parsing of the SHORTCODE.
> > Perhaps the only thing for the short term is to have the generator grep
> > genptr.c for "#define fGEN", to choose between the two alternatives:
> inline
> > generation or out-of-line helper generation.
>
> That's certainly doable.  It will also be good to implement some of your other
> ideas
> - Have the generator expand the DECL/READ/WRITE/FREE macros will make
> the generated code more readable and we can specialize them for
> predicated vs non-predicated instructions which will make translation faster.
> - Generate the entire generate_<tag> function instead of just the body will
> make the generated code more readable.

I've made these changes to the generator.  I hope you like the results.  As an 
example, here is what we generate for the add instruction

DEF_TCG_FUNC(A2_add,
static void generate_A2_add(
                CPUHexagonState *env,
                DisasContext *ctx,
                insn_t *insn,
                packet_t *pkt)
{
    TCGv RdV = tcg_temp_local_new();
    const int RdN = insn->regno[0];
    TCGv RsV = hex_gpr[insn->regno[1]];
    TCGv RtV = hex_gpr[insn->regno[2]];
    gen_helper_A2_add(RdV, cpu_env, RsV, RtV);
    gen_log_reg_write(RdN, RdV);
    ctx_log_reg_write(ctx, RdN);
    tcg_temp_free(RdV);
})

And here is how the generated file gets used in genptr.c

#define DEF_TCG_FUNC(TAG, GENFN) \
    GENFN
#include "tcg_funcs_generated.h"
#undef DEF_TCG_FUNC

/*
 * Not all opcodes have generate_<tag> functions, so initialize
 * the table from the tcg_funcs_generated.h file.
 */
const semantic_insn_t opcode_genptr[XX_LAST_OPCODE] = {
#define DEF_TCG_FUNC(TAG, GENFN) \
    [TAG] = generate_##TAG,
#include "tcg_funcs_generated.h"
#undef DEF_TCG_FUNC
};

I've also addressed several of the items from Richard's review, so I'll 
resubmit the series once I figure out how to get "make check-tcg" working under 
meson.

Thanks,
Taylor