[U-Boot] [PATCH 1/2] arm64: use xzr to zero-out the bss section
AArch64 has a zero register (xzr). Use it instead of x2.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com ---
arch/arm/lib/crt0_64.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S index 91b19e0..f8e84b2 100644 --- a/arch/arm/lib/crt0_64.S +++ b/arch/arm/lib/crt0_64.S @@ -117,9 +117,8 @@ relocation_return: */ ldr x0, =__bss_start /* this is auto-relocated! */ ldr x1, =__bss_end /* this is auto-relocated! */ - mov x2, #0 clear_loop: - str x2, [x0] + str xzr, [x0] add x0, x0, #8 cmp x0, x1 b.lo clear_loop
Save one instruction.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com ---
arch/arm/lib/crt0_64.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S index f8e84b2..19c6a98 100644 --- a/arch/arm/lib/crt0_64.S +++ b/arch/arm/lib/crt0_64.S @@ -118,8 +118,7 @@ relocation_return: ldr x0, =__bss_start /* this is auto-relocated! */ ldr x1, =__bss_end /* this is auto-relocated! */ clear_loop: - str xzr, [x0] - add x0, x0, #8 + str xzr, [x0], #8 cmp x0, x1 b.lo clear_loop
On 26 January 2017 at 23:15, Masahiro Yamada yamada.masahiro@socionext.com wrote:
Save one instruction.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com
arch/arm/lib/crt0_64.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org
On Fri, Jan 27, 2017 at 04:15:30PM +0900, Masahiro Yamada wrote:
Save one instruction.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Reviewed-by: Simon Glass sjg@chromium.org
Applied to u-boot/master, thanks!
On 26 January 2017 at 23:15, Masahiro Yamada yamada.masahiro@socionext.com wrote:
AArch64 has a zero register (xzr). Use it instead of x2.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com
arch/arm/lib/crt0_64.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org
On Fri, Jan 27, 2017 at 04:15:29PM +0900, Masahiro Yamada wrote:
AArch64 has a zero register (xzr). Use it instead of x2.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Reviewed-by: Simon Glass sjg@chromium.org
Applied to u-boot/master, thanks!
participants (3)
-
Masahiro Yamada -
Simon Glass -
Tom Rini