kernel_optimize_test

History

Nicolas Pitre 16f719de62 [ARM] 5196/1: fix inline asm constraints for preload With gcc 4.3 and later, a pointer that has already been dereferenced is assumed not to be null since it should have caused a segmentation fault otherwise, hence any subsequent test against NULL is optimized away. Current inline asm constraint used in the implementation of prefetch() makes gcc believe that the pointer is dereferenced even though the PLD instruction does not load any data and does not cause a segmentation fault on null pointers, which causes all sorts of interesting results when reaching the end of a linked lists for example. Let's use a better constraint to properly represent the actual usage of the pointer value. Problem reported by Chris Steel. Signed-off-by: Nicolas Pitre <nico@marvell.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>	2008-08-16 09:30:05 +01:00
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asm	[ARM] 5196/1: fix inline asm constraints for preload	2008-08-16 09:30:05 +01:00

Nicolas Pitre 16f719de62 [ARM] 5196/1: fix inline asm constraints for preload

With gcc 4.3 and later, a pointer that has already been dereferenced is
assumed not to be null since it should have caused a segmentation fault
otherwise, hence any subsequent test against NULL is optimized away.

Current inline asm constraint used in the implementation of prefetch()
makes gcc believe that the pointer is dereferenced even though the PLD
instruction does not load any data and does not cause a segmentation
fault on null pointers, which causes all sorts of interesting results
when reaching the end of a linked lists for example.

Let's use a better constraint to properly represent the actual usage of
the pointer value.

Problem reported by Chris Steel.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2008-08-16 09:30:05 +01:00

asm

[ARM] 5196/1: fix inline asm constraints for preload

2008-08-16 09:30:05 +01:00