| Message ID | 20220131110201.2303275-6-philipp.tomsich@vrull.eu |
|---|---|
| State | New |
| Headers | show |
| Series | target/riscv: Add XVentanaCondOps and supporting infrastructure changes | expand |
On Mon, Jan 31, 2022 at 9:32 PM Philipp Tomsich <philipp.tomsich@vrull.eu> wrote: > > To split up the decoder into multiple functions (both to support > vendor-specific opcodes in separate files and to simplify maintenance > of orthogonal extensions), this changes decode_op to iterate over a > table of decoders predicated on guard functions. > > This commit only adds the new structure and the table, allowing for > the easy addition of additional decoders in the future. > > Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu> > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Alistair > > --- > > (no changes since v4) > > Changes in v4: > - add braces to comply with coding standard (as suggested by Richard) > - merge the two if-statements to reduce clutter after (now that the > braces have been added) > > Changes in v3: > - expose only the DisasContext* to predicate functions > - mark the table of decoder functions as static > - drop the inline from always_true_p, until the need arises (i.e., > someone finds a use for it and calls it directly) > - rewrite to drop the 'handled' temporary in iterating over the > decoder table, removing the assignment in the condition of the if > > Changes in v2: > - (new patch) iterate over a table of guarded decoder functions > > target/riscv/translate.c | 32 +++++++++++++++++++++++++++----- > 1 file changed, 27 insertions(+), 5 deletions(-) > > diff --git a/target/riscv/translate.c b/target/riscv/translate.c > index f19d5cd0c0..30b1b68341 100644 > --- a/target/riscv/translate.c > +++ b/target/riscv/translate.c > @@ -111,6 +111,11 @@ static inline bool has_ext(DisasContext *ctx, uint32_t ext) > return ctx->misa_ext & ext; > } > > +static bool always_true_p(DisasContext *ctx __attribute__((__unused__))) > +{ > + return true; > +} > + > #ifdef TARGET_RISCV32 > #define get_xl(ctx) MXL_RV32 > #elif defined(CONFIG_USER_ONLY) > @@ -855,15 +860,26 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc) > > static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode) > { > - /* check for compressed insn */ > + /* > + * A table with predicate (i.e., guard) functions and decoder functions > + * that are tested in-order until a decoder matches onto the opcode. > + */ > + static const struct { > + bool (*guard_func)(DisasContext *); > + bool (*decode_func)(DisasContext *, uint32_t); > + } decoders[] = { > + { always_true_p, decode_insn32 }, > + }; > + > + /* Check for compressed insn */ > if (extract16(opcode, 0, 2) != 3) { > if (!has_ext(ctx, RVC)) { > gen_exception_illegal(ctx); > } else { > ctx->opcode = opcode; > ctx->pc_succ_insn = ctx->base.pc_next + 2; > - if (!decode_insn16(ctx, opcode)) { > - gen_exception_illegal(ctx); > + if (decode_insn16(ctx, opcode)) { > + return; > } > } > } else { > @@ -873,10 +889,16 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode) > ctx->base.pc_next + 2)); > ctx->opcode = opcode32; > ctx->pc_succ_insn = ctx->base.pc_next + 4; > - if (!decode_insn32(ctx, opcode32)) { > - gen_exception_illegal(ctx); > + > + for (size_t i = 0; i < ARRAY_SIZE(decoders); ++i) { > + if (decoders[i].guard_func(ctx) && > + decoders[i].decode_func(ctx, opcode32)) { > + return; > + } > } > } > + > + gen_exception_illegal(ctx); > } > > static void riscv_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs) > -- > 2.33.1 > >
diff --git a/target/riscv/translate.c b/target/riscv/translate.c index f19d5cd0c0..30b1b68341 100644 --- a/target/riscv/translate.c +++ b/target/riscv/translate.c @@ -111,6 +111,11 @@ static inline bool has_ext(DisasContext *ctx, uint32_t ext) return ctx->misa_ext & ext; } +static bool always_true_p(DisasContext *ctx __attribute__((__unused__))) +{ + return true; +} + #ifdef TARGET_RISCV32 #define get_xl(ctx) MXL_RV32 #elif defined(CONFIG_USER_ONLY) @@ -855,15 +860,26 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc) static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode) { - /* check for compressed insn */ + /* + * A table with predicate (i.e., guard) functions and decoder functions + * that are tested in-order until a decoder matches onto the opcode. + */ + static const struct { + bool (*guard_func)(DisasContext *); + bool (*decode_func)(DisasContext *, uint32_t); + } decoders[] = { + { always_true_p, decode_insn32 }, + }; + + /* Check for compressed insn */ if (extract16(opcode, 0, 2) != 3) { if (!has_ext(ctx, RVC)) { gen_exception_illegal(ctx); } else { ctx->opcode = opcode; ctx->pc_succ_insn = ctx->base.pc_next + 2; - if (!decode_insn16(ctx, opcode)) { - gen_exception_illegal(ctx); + if (decode_insn16(ctx, opcode)) { + return; } } } else { @@ -873,10 +889,16 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode) ctx->base.pc_next + 2)); ctx->opcode = opcode32; ctx->pc_succ_insn = ctx->base.pc_next + 4; - if (!decode_insn32(ctx, opcode32)) { - gen_exception_illegal(ctx); + + for (size_t i = 0; i < ARRAY_SIZE(decoders); ++i) { + if (decoders[i].guard_func(ctx) && + decoders[i].decode_func(ctx, opcode32)) { + return; + } } } + + gen_exception_illegal(ctx); } static void riscv_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)