@@ -35,11 +35,34 @@ typedef abi_ulong tb_page_addr_t;
typedef ram_addr_t tb_page_addr_t;
#endif
-/* is_jmp field values */
+/* DisasContext is_jmp field values
+ *
+ * is_jmp starts as DISAS_NEXT. The translator will keep processing
+ * instructions until an exit condition is reached. If we reach the
+ * exit condition and is_jmp is still DISAS_NEXT (because of some
+ * other condition) we simply "jump" to the next address.
+ * The remaining exit cases are:
+ *
+ * DISAS_JUMP - Only the PC was modified dynamically (e.g computed)
+ * DISAS_TB_JUMP - Only the PC was modified statically (e.g. branch)
+ *
+ * In these cases as long as the PC is updated we can chain to the
+ * next TB either by exiting the loop or looking up the next TB via
+ * the loookup helper.
+ *
+ * DISAS_UPDATE - CPU State was modified dynamically
+ *
+ * This covers any other CPU state which necessities us exiting the
+ * TCG code to the main run-loop. Typically this includes anything
+ * that might change the interrupt state.
+ *
+ * Individual translators may define additional exit cases to deal
+ * with per-target special conditions.
+ */
#define DISAS_NEXT 0 /* next instruction can be analyzed */
#define DISAS_JUMP 1 /* only pc was modified dynamically */
-#define DISAS_UPDATE 2 /* cpu state was modified dynamically */
-#define DISAS_TB_JUMP 3 /* only pc was modified statically */
+#define DISAS_TB_JUMP 2 /* only pc was modified statically */
+#define DISAS_UPDATE 3 /* cpu state was modified dynamically */
#include "qemu/log.h"
As a precursor to later patches attempt to come up with a more concrete wording for what each of the common exit cases would be. CC: Emilio G. Cota <cota@braap.org> CC: Richard Henderson <rth@twiddle.net> CC: Lluís Vilanova <vilanova@ac.upc.edu> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> --- include/exec/exec-all.h | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) -- 2.13.0