Emilio G. Cota <c...@braap.org> writes:
> Instead of exporting goto_ptr directly to TCG frontends, export
> tcg_gen_lookup_and_goto_ptr(), which calls goto_ptr with the pointer
> returned by the lookup_tb_ptr() helper. This is the only use case
> we have for goto_ptr and lookup_tb_ptr, so having this function is
> very convenient. Furthermore, it trivially allows us to avoid calling
> the lookup helper if goto_ptr is not implemented by the backend.
>
> Signed-off-by: Emilio G. Cota <c...@braap.org>
Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
> ---
> tcg/README | 8 ++++++++
> tcg/tcg-op.c | 13 +++++++++++++
> tcg/tcg-op.h | 11 +++++++++++
> 3 files changed, 32 insertions(+)
>
> diff --git a/tcg/README b/tcg/README
> index a9858c2..bf49e82 100644
> --- a/tcg/README
> +++ b/tcg/README
> @@ -477,6 +477,14 @@ current TB was linked to this TB. Otherwise execute the
> next
> instructions. Only indices 0 and 1 are valid and tcg_gen_goto_tb may be
> issued
> at most once with each slot index per TB.
>
> +* lookup_and_goto_ptr tb_addr
> +
> +Look up a TB address ('tb_addr') and jump to it if valid. If not valid,
> +jump to the TCG epilogue to go back to the exec loop.
> +
> +This operation is optional. If the TCG backend does not implement the
> +goto_ptr opcode, emitting this op is equivalent to emitting exit_tb(0).
> +
> * qemu_ld_i32/i64 t0, t1, flags, memidx
> * qemu_st_i32/i64 t0, t1, flags, memidx
>
> diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
> index 95a39b7..8ff1eaf 100644
> --- a/tcg/tcg-op.c
> +++ b/tcg/tcg-op.c
> @@ -2587,6 +2587,19 @@ void tcg_gen_goto_tb(unsigned idx)
> tcg_gen_op1i(INDEX_op_goto_tb, idx);
> }
>
> +void tcg_gen_lookup_and_goto_ptr(TCGv addr)
> +{
> + if (TCG_TARGET_HAS_goto_ptr) {
> + TCGv_ptr ptr = tcg_temp_new_ptr();
> +
> + gen_helper_lookup_tb_ptr(ptr, tcg_ctx.tcg_env, addr);
> + tcg_gen_op1i(INDEX_op_goto_ptr, GET_TCGV_PTR(ptr));
> + tcg_temp_free_ptr(ptr);
> + } else {
> + tcg_gen_exit_tb(0);
> + }
> +}
> +
> static inline TCGMemOp tcg_canonicalize_memop(TCGMemOp op, bool is64, bool
> st)
> {
> /* Trigger the asserts within as early as possible. */
> diff --git a/tcg/tcg-op.h b/tcg/tcg-op.h
> index c68e300..5d3278f 100644
> --- a/tcg/tcg-op.h
> +++ b/tcg/tcg-op.h
> @@ -796,6 +796,17 @@ static inline void tcg_gen_exit_tb(uintptr_t val)
> */
> void tcg_gen_goto_tb(unsigned idx);
>
> +/**
> + * tcg_gen_lookup_and_goto_ptr() - look up a TB and jump to it if valid
> + * @addr: Guest address of the target TB
> + *
> + * If the TB is not valid, jump to the epilogue.
> + *
> + * This operation is optional. If the TCG backend does not implement
> goto_ptr,
> + * this op is equivalent to calling tcg_gen_exit_tb() with 0 as the argument.
> + */
> +void tcg_gen_lookup_and_goto_ptr(TCGv addr);
> +
> #if TARGET_LONG_BITS == 32
> #define tcg_temp_new() tcg_temp_new_i32()
> #define tcg_global_reg_new tcg_global_reg_new_i32
--
Alex Bennée
