Commit a31d8e0e authored by Vineet Gupta's avatar Vineet Gupta Committed by Kamal Mostafa

ARC: bitops: Remove non relevant comments

commit 2a41b6dc upstream.

commit 80f42084 removed the ARC bitops microoptimization but failed
to prune the comments to same effect

Fixes: 80f42084 ("ARC: Make ARC bitops "safer" (add anti-optimization)")
Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
parent 9c6b50ce
...@@ -35,21 +35,6 @@ static inline void op##_bit(unsigned long nr, volatile unsigned long *m)\ ...@@ -35,21 +35,6 @@ static inline void op##_bit(unsigned long nr, volatile unsigned long *m)\
\ \
m += nr >> 5; \ 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; \ nr &= 0x1f; \
\ \
__asm__ __volatile__( \ __asm__ __volatile__( \
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment