diff options
Diffstat (limited to 'tcg/README')
| -rw-r--r-- | tcg/README | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/tcg/README b/tcg/README index 9d1b100613..ec1ac79375 100644 --- a/tcg/README +++ b/tcg/README @@ -77,11 +77,20 @@ destroyed, but local temporaries and globals are preserved. Using the tcg_gen_helper_x_y it is possible to call any function taking i32, i64 or pointer types. By default, before calling a helper, all globals are stored at their canonical location and it is assumed -that the function can modify them. This can be overridden by the -TCG_CALL_CONST function modifier. By default, the helper is allowed to -modify the CPU state or raise an exception. This can be overridden by -the TCG_CALL_PURE function modifier, in which case the call to the -function is removed if the return value is not used. +that the function can modify them. By default, the helper is allowed to +modify the CPU state or raise an exception. + +This can be overridden using the following function modifiers: +- 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 locations 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 location 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. + +Note that TCG_CALL_NO_READ_GLOBALS implies TCG_CALL_NO_WRITE_GLOBALS. On some TCG targets (e.g. x86), several calling conventions are supported. |