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| author | Aurelien Jarno <aurelien@aurel32.net> | 2012-09-19 22:00:22 +0200 |
|---|---|---|
| committer | Aurelien Jarno <aurelien@aurel32.net> | 2012-09-22 15:10:21 +0200 |
| commit | c2b0e2fea2ef7a183233d3b86c37c5d4bcb89544 (patch) | |
| tree | f24aab079acff1f803b587fca58fa53b1c7cd183 /tcg/optimize.c | |
| parent | b336ceb6918b8f9eb54dcbb1043521482c7be83b (diff) | |
| download | qemu-c2b0e2fea2ef7a183233d3b86c37c5d4bcb89544.tar.gz | |
tcg/optimize: prefer the "op a, a, b" form for commutative ops
The "op a, a, b" form is better handled on non-RISC host than the "op
a, b, a" form, so swap the arguments to this form when possible, and
when b is not a constant.
This reduces the number of generated instructions by a tiny bit.
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Diffstat (limited to 'tcg/optimize.c')
| -rw-r--r-- | tcg/optimize.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/tcg/optimize.c b/tcg/optimize.c index abe016a28a..c8ae50bc91 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -434,7 +434,10 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, CASE_OP_32_64(eqv): CASE_OP_32_64(nand): CASE_OP_32_64(nor): - if (temps[args[1]].state == TCG_TEMP_CONST) { + /* Prefer the constant in second argument, and then the form + op a, a, b, which is better handled on non-RISC hosts. */ + if (temps[args[1]].state == TCG_TEMP_CONST || (args[0] == args[2] + && temps[args[2]].state != TCG_TEMP_CONST)) { tmp = args[1]; args[1] = args[2]; args[2] = tmp; |