[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v2 06/10] tcg/optimize: optimize "op r, a, a => movi
From: |
Aurelien Jarno |
Subject: |
[Qemu-devel] [PATCH v2 06/10] tcg/optimize: optimize "op r, a, a => movi r, 0" |
Date: |
Fri, 21 Sep 2012 21:43:14 +0200 |
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 <address@hidden>
Signed-off-by: Aurelien Jarno <address@hidden>
---
tcg/optimize.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/tcg/optimize.c b/tcg/optimize.c
index b9a7da9..ceea644 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. */
--
1.7.10.4
- [Qemu-devel] [PATCH v2 00/10] tcg/optimize: rework copy propagation, Aurelien Jarno, 2012/09/21
- [Qemu-devel] [PATCH v2 06/10] tcg/optimize: optimize "op r, a, a => movi r, 0",
Aurelien Jarno <=
- [Qemu-devel] [PATCH v2 08/10] tcg/optimize: prefer the "op a, a, b" form for commutative ops, Aurelien Jarno, 2012/09/21
- [Qemu-devel] [PATCH v2 01/10] tcg/optimize: remove TCG_TEMP_ANY, Aurelien Jarno, 2012/09/21
- [Qemu-devel] [PATCH v2 10/10] tcg/optimize: add constant folding for deposit, Aurelien Jarno, 2012/09/21
- [Qemu-devel] [PATCH v2 02/10] tcg/optimize: check types in copy propagation, Aurelien Jarno, 2012/09/21
- [Qemu-devel] [PATCH v2 07/10] tcg/optimize: further optimize brcond/movcond/setcond, Aurelien Jarno, 2012/09/21