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[Qemu-devel] [PATCH v6 18/50] tcg: Reserve temporary index 0
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH v6 18/50] tcg: Reserve temporary index 0 |
Date: |
Mon, 16 Oct 2017 10:25:37 -0700 |
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 <address@hidden>
---
tcg/tcg.h | 16 ++++++++--------
tcg/tcg.c | 5 ++++-
2 files changed, 12 insertions(+), 9 deletions(-)
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 */
--
2.13.6
- [Qemu-devel] [PATCH v6 12/50] tcg: Remove unused TCG_CALL_DUMMY_TCGV, (continued)
- [Qemu-devel] [PATCH v6 12/50] tcg: Remove unused TCG_CALL_DUMMY_TCGV, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 09/50] tcg: Use per-temp state data in liveness, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 13/50] tcg: Export temp_idx, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 15/50] tcg: Push tcg_ctx into generator functions, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 16/50] tcg: Push tcg_ctx into tcg_gen_callN, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 18/50] tcg: Reserve temporary index 0,
Richard Henderson <=
- [Qemu-devel] [PATCH v6 17/50] tcg: Introduce index_arg, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 19/50] target/alpha: Avoid translate_init unless tcg_enabled, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 14/50] tcg: Use per-temp state data in optimize, Richard Henderson, 2017/10/16
- [Qemu-devel] [PATCH v6 21/50] tcg: Use pointers in TCGOp->args, Richard Henderson, 2017/10/16