| Message ID | 20171016172609.23422-19-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | tcg tb_lock removal | expand |
On Mon, Oct 16, 2017 at 10:25:37 -0700, Richard Henderson wrote: > Since we cast indicies to pointers, reserving 0 allows s/indicies/indices/ > us to use NULL for unused/dummy instead of (T *)-1. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- (snip) > @@ -737,7 +737,7 @@ extern bool parallel_cpus; > static inline size_t temp_idx(TCGTemp *ts) > { > ptrdiff_t n = ts - tcg_ctx.temps; > - tcg_debug_assert(n >= 0 && n < tcg_ctx.nb_temps); > + tcg_debug_assert(n > 0 && n < tcg_ctx.nb_temps); > return n; > } > > diff --git a/tcg/tcg.c b/tcg/tcg.c > index 129aecca60..7cf39f7067 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -333,7 +333,10 @@ void tcg_context_init(TCGContext *s) > int *sorted_args; > > memset(s, 0, sizeof(*s)); > - s->nb_globals = 0; > + /* Reserve temp index 0 so that, with the funny casting that we do, > + the first one doesn't look like NULL. */ > + s->nb_globals = 1; > + s->nb_temps = 1; > > /* Count total number of arguments and allocate the corresponding > space */ I like this change, although operating on the 0th element makes me uneasy. For instance, I managed to trigger the above assert by manually calling dump_regs (it is otherwise called before aborting, which is why you missed it.) This fixes it: diff --git a/tcg/tcg.c b/tcg/tcg.c index 7cf39f7..49176e0 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -2034,7 +2034,7 @@ static void dump_regs(TCGContext *s) int i; char buf[64]; - for(i = 0; i < s->nb_temps; i++) { + for (i = 1; i < s->nb_temps; i++) { ts = &s->temps[i]; printf(" %10s: ", tcg_get_arg_str_ptr(s, buf, sizeof(buf), ts)); switch(ts->val_type) { Is it worth changing other [0, nb_temps/globals) loops to start from 1? Thanks, E.
diff --git a/tcg/tcg.h b/tcg/tcg.h index b8ede7fe5c..ccf1bcdaf6 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -471,13 +471,13 @@ static inline intptr_t QEMU_ARTIFICIAL GET_TCGV_PTR(TCGv_ptr t) #define TCGV_EQUAL_PTR(a, b) (GET_TCGV_PTR(a) == GET_TCGV_PTR(b)) /* Dummy definition to avoid compiler warnings. */ -#define TCGV_UNUSED_I32(x) x = MAKE_TCGV_I32(-1) -#define TCGV_UNUSED_I64(x) x = MAKE_TCGV_I64(-1) -#define TCGV_UNUSED_PTR(x) x = MAKE_TCGV_PTR(-1) +#define TCGV_UNUSED_I32(x) ((x) = NULL) +#define TCGV_UNUSED_I64(x) ((x) = NULL) +#define TCGV_UNUSED_PTR(x) ((x) = NULL) -#define TCGV_IS_UNUSED_I32(x) (GET_TCGV_I32(x) == -1) -#define TCGV_IS_UNUSED_I64(x) (GET_TCGV_I64(x) == -1) -#define TCGV_IS_UNUSED_PTR(x) (GET_TCGV_PTR(x) == -1) +#define TCGV_IS_UNUSED_I32(x) (GET_TCGV_I32(x) == 0) +#define TCGV_IS_UNUSED_I64(x) (GET_TCGV_I64(x) == 0) +#define TCGV_IS_UNUSED_PTR(x) (GET_TCGV_PTR(x) == 0) /* call flags */ /* Helper does not read globals (either directly or through an exception). It @@ -496,7 +496,7 @@ static inline intptr_t QEMU_ARTIFICIAL GET_TCGV_PTR(TCGv_ptr t) #define TCG_CALL_NO_WG_SE (TCG_CALL_NO_WG | TCG_CALL_NO_SE) /* used to align parameters */ -#define TCG_CALL_DUMMY_ARG ((TCGArg)(-1)) +#define TCG_CALL_DUMMY_ARG ((TCGArg)0) /* Conditions. Note that these are laid out for easy manipulation by the functions below: @@ -737,7 +737,7 @@ extern bool parallel_cpus; static inline size_t temp_idx(TCGTemp *ts) { ptrdiff_t n = ts - tcg_ctx.temps; - tcg_debug_assert(n >= 0 && n < tcg_ctx.nb_temps); + tcg_debug_assert(n > 0 && n < tcg_ctx.nb_temps); return n; } diff --git a/tcg/tcg.c b/tcg/tcg.c index 129aecca60..7cf39f7067 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -333,7 +333,10 @@ void tcg_context_init(TCGContext *s) int *sorted_args; memset(s, 0, sizeof(*s)); - s->nb_globals = 0; + /* Reserve temp index 0 so that, with the funny casting that we do, + the first one doesn't look like NULL. */ + s->nb_globals = 1; + s->nb_temps = 1; /* Count total number of arguments and allocate the corresponding space */
Since we cast indicies to pointers, reserving 0 allows us to use NULL for unused/dummy instead of (T *)-1. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- tcg/tcg.h | 16 ++++++++-------- tcg/tcg.c | 5 ++++- 2 files changed, 12 insertions(+), 9 deletions(-) -- 2.13.6