tcg: Reset free_temps before tcg_optimize

When allocating new temps during tcg_optmize, do not re-use
any EBB temps that were used within the TB.  We do not have
any idea what span of the TB in which the temp was live.

Introduce tcg_temp_ebb_reset_freed and use before tcg_optimize,
as well as replacing the equivalent in plugin_gen_inject and
tcg_func_start.

Cc: qemu-stable@nongnu.org
Fixes: fb04ab7ddd8 ("tcg/optimize: Lower TCG_COND_TST{EQ,NE} if unsupported")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2711
Reported-by: wannacu <wannacu2049@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
(cherry picked from commit 04e006ab36a8565b92d4e21dd346367fbade7d74)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/accel/tcg/plugin-gen.c b/accel/tcg/plugin-gen.c
index 99643dd9600313cb0fda0d510d6a2a6f71dca49e..e6327d4fe13261c3acf7fa3d7e17a03fda3feacf 100644 (file)
--- a/accel/tcg/plugin-gen.c
+++ b/accel/tcg/plugin-gen.c
@@ -276,7 +276,7 @@ static void plugin_gen_inject(struct qemu_plugin_tb *plugin_tb)
      * that might be live within the existing opcode stream.
      * The simplest solution is to release them all and create new.
      */
-    memset(tcg_ctx->free_temps, 0, sizeof(tcg_ctx->free_temps));
+    tcg_temp_ebb_reset_freed(tcg_ctx);
 
     QTAILQ_FOREACH_SAFE(op, &tcg_ctx->ops, link, next) {
         switch (op->opc) {

diff --git a/include/tcg/tcg-temp-internal.h b/include/tcg/tcg-temp-internal.h
index 44192c55a9d503cf5a685af6c87a464c0bc4949d..98f91e68b70c5501aeaca0ea8dfce8fc49db7e12 100644 (file)
--- a/include/tcg/tcg-temp-internal.h
+++ b/include/tcg/tcg-temp-internal.h
@@ -42,4 +42,10 @@ TCGv_i64 tcg_temp_ebb_new_i64(void);
 TCGv_ptr tcg_temp_ebb_new_ptr(void);
 TCGv_i128 tcg_temp_ebb_new_i128(void);
 
+/* Forget all freed EBB temps, so that new allocations produce new temps. */
+static inline void tcg_temp_ebb_reset_freed(TCGContext *s)
+{
+    memset(s->free_temps, 0, sizeof(s->free_temps));
+}
+
 #endif /* TCG_TEMP_FREE_H */

diff --git a/tcg/tcg.c b/tcg/tcg.c
index b1b8b8bba3827dbb4d9a3e0d2c1cbf1000220638..e1f6c0f5731f5bf5c0e2dc9ea205daf474925af6 100644 (file)
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1489,7 +1489,7 @@ void tcg_func_start(TCGContext *s)
     s->nb_temps = s->nb_globals;
 
     /* No temps have been previously allocated for size or locality.  */
-    memset(s->free_temps, 0, sizeof(s->free_temps));
+    tcg_temp_ebb_reset_freed(s);
 
     /* No constant temps have been previously allocated. */
     for (int i = 0; i < TCG_TYPE_COUNT; ++i) {
@@ -6120,6 +6120,9 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb, uint64_t pc_start)
     }
 #endif
 
+    /* Do not reuse any EBB that may be allocated within the TB. */
+    tcg_temp_ebb_reset_freed(s);
+
     tcg_optimize(s);
 
     reachable_code_pass(s);