diff options
| author | aurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162> | 2009-04-06 12:33:59 +0000 |
|---|---|---|
| committer | aurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162> | 2009-04-06 12:33:59 +0000 |
| commit | b9c18f56585ab146c6a25084bce00e4c52eefcc6 (patch) | |
| tree | 20207c890dcc4976359e5e1e833fd48a70a6fc77 /tcg | |
| parent | 34d5a9ff634b1cafdd164cfe19e167b55084f6b8 (diff) | |
tcg: add a CONST flag to TCG helpers
A const function only reads its arguments and does not use TCG
globals variables. Hence a call to such a function does not
save TCG globals variabes back to their canonical location.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7008 c046a42c-6fe2-441c-8c8c-71466251a162
Diffstat (limited to 'tcg')
| -rw-r--r-- | tcg/tcg.c | 12 | ||||
| -rw-r--r-- | tcg/tcg.h | 4 |
2 files changed, 12 insertions, 4 deletions
@@ -1122,9 +1122,11 @@ static void tcg_liveness_analysis(TCGContext *s) dead_temps[arg] = 1; } - /* globals are live (they may be used by the call) */ - memset(dead_temps, 0, s->nb_globals); - + if (!(call_flags & TCG_CALL_CONST)) { + /* globals are live (they may be used by the call) */ + memset(dead_temps, 0, s->nb_globals); + } + /* input args are live */ dead_iargs = 0; for(i = 0; i < nb_iargs; i++) { @@ -1821,7 +1823,9 @@ static int tcg_reg_alloc_call(TCGContext *s, const TCGOpDef *def, /* store globals and free associated registers (we assume the call can modify any global. */ - save_globals(s, allocated_regs); + if (!(flags & TCG_CALL_CONST)) { + save_globals(s, allocated_regs); + } tcg_out_op(s, opc, &func_arg, &const_func_arg); @@ -178,6 +178,10 @@ typedef int TCGv_i64; 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 + globals variables. Hence a call to such a function does not + save TCG globals variabes back to their canonical location. */ +#define TCG_CALL_CONST 0x0020 /* used to align parameters */ #define TCG_CALL_DUMMY_TCGV MAKE_TCGV_I32(-1) |