Commits
Robin Murphy committed ee5e41b5f21
arm64/io: Allow I/O writes to use {W,X}ZR
When zeroing an I/O location, the current accessors are forced to
allocate a temporary register to store the zero for the write. By
tweaking the assembly constraints, we can allow the compiler to use
the zero register directly in such cases, and save some juggling.
Compiling a representative kernel configuration with GCC 6 shows
that 2.3KB worth of code can be wasted just on that!
text data bss dec hex filename
13316776 3248256 18176769 34741801 2121e29 vmlinux.o.new
13319140 3248256 18176769 34744165 2122765 vmlinux.o.old
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>