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[4.2.y-ckt,stable] Patch "ARC: bitops: Remove non relevant comments" has been added to the 4.2.y-ckt tree

Message ID 1459382039-6751-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa March 30, 2016, 11:53 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    ARC: bitops: Remove non relevant comments

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

From 753ea36aaa50fdcfdfcd515c5ae3f08ddb87e606 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 8 Mar 2016 19:31:24 +0530
Subject: ARC: bitops: Remove non relevant comments

commit 2a41b6dc28dc71c1a3f1622612a26edc58f7561e upstream.

commit 80f420842ff42 removed the ARC bitops microoptimization but failed
to prune the comments to same effect

Fixes: 80f420842ff42 ("ARC: Make ARC bitops "safer" (add anti-optimization)")
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 arch/arc/include/asm/bitops.h | 15 ---------------
 1 file changed, 15 deletions(-)

--
2.7.4
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Patch

diff --git a/arch/arc/include/asm/bitops.h b/arch/arc/include/asm/bitops.h
index 57c1f33..0352fb8 100644
--- a/arch/arc/include/asm/bitops.h
+++ b/arch/arc/include/asm/bitops.h
@@ -35,21 +35,6 @@  static inline void op##_bit(unsigned long nr, volatile unsigned long *m)\
 									\
 	m += nr >> 5;							\
 									\
-	/*								\
-	 * ARC ISA micro-optimization:					\
-	 *								\
-	 * Instructions dealing with bitpos only consider lower 5 bits	\
-	 * e.g (x << 33) is handled like (x << 1) by ASL instruction	\
-	 *  (mem pointer still needs adjustment to point to next word)	\
-	 *								\
-	 * Hence the masking to clamp @nr arg can be elided in general.	\
-	 *								\
-	 * However if @nr is a constant (above assumed in a register),	\
-	 * and greater than 31, gcc can optimize away (x << 33) to 0,	\
-	 * as overflow, given the 32-bit ISA. Thus masking needs to be	\
-	 * done for const @nr, but no code is generated due to gcc	\
-	 * const prop.							\
-	 */								\
 	nr &= 0x1f;							\
 									\
 	__asm__ __volatile__(						\