From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>
Cc: scottwood@freescale.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v3 10/21] powerpc/8xx: Duplicate two insns instead of branching
Date: Wed, 17 Sep 2014 18:36:58 +0200 (CEST) [thread overview]
Message-ID: <20140917163658.A53861AB039@localhost.localdomain> (raw)
Branching takes two cycles on MPC8xx. Lets duplicate the two instructions
and avoid the branching.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
Changes in v2:
- None
Changes in v3:
- None
arch/powerpc/kernel/head_8xx.S | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5037420..4a49ff3 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -638,9 +638,11 @@ modified_instr:
/* special handling for r10,r11 since these are modified already */
153: mfspr r11, SPRN_SPRG_SCRATCH1 /* load r11 from SPRN_SPRG_SCRATCH1 */
- b 155f
+ add r10, r10, r11 /* add it */
+ mfctr r11 /* restore r11 */
+ b 151b
154: mfspr r11, SPRN_SPRG_SCRATCH0 /* load r10 from SPRN_SPRG_SCRATCH0 */
-155: add r10, r10, r11 /* add it */
+ add r10, r10, r11 /* add it */
mfctr r11 /* restore r11 */
b 151b
#endif
--
1.7.1
reply other threads:[~2014-09-17 16:37 UTC|newest]
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