tcg: rework TCG helper flags
The current helper flags, TCG_CALL_CONST and TCG_CALL_PURE might be
confusing and doesn't provide enough granularity for some helpers (FP
helpers for example).
This patch changes them into the following helpers flags:
- TCG_CALL_NO_READ_GLOBALS means that the helper does not read globals,
either directly or via an exception. They will not be saved to their
canonical location before calling the helper.
- TCG_CALL_NO_WRITE_GLOBALS means that the helper does not modify any
globals. They will only be saved to their canonical locations before
calling helpers, but they won't be reloaded afterwise.
- TCG_CALL_NO_SIDE_EFFECTS means that the call to the function is
removed if the return value is not used.
It provides convenience flags, to avoid helper definitions longer than
80 characters. It also provides compatibility flags, and updates the
documentation.
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/tcg/tcg.h b/tcg/tcg.h
index 4b44ecd..96b6222 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -253,14 +253,24 @@
#define TCGV_UNUSED_I64(x) x = MAKE_TCGV_I64(-1)
/* call flags */
-/* A pure function only reads its arguments and TCG global variables
- and cannot raise exceptions. Hence a call to a pure function can be
- safely suppressed if the return value is not used. */
-#define TCG_CALL_PURE 0x0010
-/* A const function only reads its arguments and does not use TCG
- global variables. Hence a call to such a function does not
- save TCG global variables back to their canonical location. */
-#define TCG_CALL_CONST 0x0020
+/* Helper does not read globals (either directly or through an exception). It
+ implies TCG_CALL_NO_WRITE_GLOBALS. */
+#define TCG_CALL_NO_READ_GLOBALS 0x0010
+/* Helper does not write globals */
+#define TCG_CALL_NO_WRITE_GLOBALS 0x0020
+/* Helper can be safely suppressed if the return value is not used. */
+#define TCG_CALL_NO_SIDE_EFFECTS 0x0040
+
+/* convenience version of most used call flags */
+#define TCG_CALL_NO_RWG TCG_CALL_NO_READ_GLOBALS
+#define TCG_CALL_NO_WG TCG_CALL_NO_WRITE_GLOBALS
+#define TCG_CALL_NO_SE TCG_CALL_NO_SIDE_EFFECTS
+#define TCG_CALL_NO_RWG_SE (TCG_CALL_NO_RWG | TCG_CALL_NO_SE)
+#define TCG_CALL_NO_WG_SE (TCG_CALL_NO_WG | TCG_CALL_NO_SE)
+
+/* compatibility call flags, they should be eventually be removed */
+#define TCG_CALL_PURE TCG_CALL_NO_SIDE_EFFECTS
+#define TCG_CALL_CONST TCG_CALL_NO_READ_GLOBALS
/* used to align parameters */
#define TCG_CALL_DUMMY_TCGV MAKE_TCGV_I32(-1)
