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[Qemu-devel] [PATCH 6/9] tcg/optimize: optimize "op r, a, a => movi r, 0
From: |
Aurelien Jarno |
Subject: |
[Qemu-devel] [PATCH 6/9] tcg/optimize: optimize "op r, a, a => movi r, 0" |
Date: |
Wed, 19 Sep 2012 22:00:20 +0200 |
Now that it's possible to detect copies, we can optimize the case
the "op r, a, a => movi r, 0". This helps the computation of
overflow flags when one of the two args is 0.
Signed-off-by: Aurelien Jarno <address@hidden>
---
tcg/optimize.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/tcg/optimize.c b/tcg/optimize.c
index cfee690..f8423e0 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -519,6 +519,23 @@ 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(andc):
+ 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 0/9] tcg/optimize: rework copy propagation, Aurelien Jarno, 2012/09/19
- [Qemu-devel] [PATCH 6/9] tcg/optimize: optimize "op r, a, a => movi r, 0",
Aurelien Jarno <=
- [Qemu-devel] [PATCH 4/9] tcg/optimize: do copy propagation for all operations, Aurelien Jarno, 2012/09/19
- [Qemu-devel] [PATCH 1/9] tcg/optimizer: remove TCG_TEMP_ANY, Aurelien Jarno, 2012/09/19
- [Qemu-devel] [PATCH 9/9] tcg: remove #ifdef #endif around TCGOpcode tests, Aurelien Jarno, 2012/09/19
- [Qemu-devel] [PATCH 2/9] tcg/optimizer: check types in copy propagation, Aurelien Jarno, 2012/09/19