Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-25 21:51:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

ARC: bitops: Remove non relevant comments

Browse Source 
commit 80f420842f removed the ARC bitops microoptimization but failed
to prune the comments to same effect

Fixes: 80f420842f ("ARC: Make ARC bitops "safer" (add anti-optimization)")
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2016-03-08 19:31:24 +05:30
parent 7423cc0cae
commit 2a41b6dc28
1 changed files with 0 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
arch/arc/include/asm/bitops.h
View File

@ -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__( \