diff options
author | Aurelien Jarno <aurelien@aurel32.net> | 2012-09-18 19:12:36 +0200 |
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committer | Aurelien Jarno <aurelien@aurel32.net> | 2012-09-22 15:10:21 +0200 |
commit | 3c94193e0bbdd855bcbedabd27e3cbe1e6bc6242 (patch) | |
tree | 66acc972bc03f5d47de4488f60c5fd786cbd7d27 /tcg | |
parent | 0aba1c7376ad325202f328211ab6dfcae94c7f2a (diff) |
tcg/optimize: optimize "op r, a, a => movi r, 0"
Now that it's possible to detect copies, we can optimize the case
the "op r, a, a => movi r, 0". This helps in the computation of
overflow flags when one of the two args is 0.
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Diffstat (limited to 'tcg')
-rw-r--r-- | tcg/optimize.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/tcg/optimize.c b/tcg/optimize.c index b9a7da920f..ceea6441bc 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -540,6 +540,22 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, break; } + /* Simplify expression for "op r, a, a => movi r, 0" cases */ + switch (op) { + CASE_OP_32_64(sub): + CASE_OP_32_64(xor): + if (temps_are_copies(args[1], args[2])) { + gen_opc_buf[op_index] = op_to_movi(op); + tcg_opt_gen_movi(gen_args, args[0], 0); + gen_args += 2; + args += 3; + continue; + } + break; + default: + break; + } + /* Propagate constants through copy operations and do constant folding. Constants will be substituted to arguments by register allocator where needed and possible. Also detect copies. */ |