On Thu, 2011-02-24 at 18:44 +0000, Stephen Boyd wrote:
> Assign the registers used in the inline assembly immediately
> before the inline assembly block. This ensures the compiler
> doesn't optimize away dead register assignments when it
> shouldn't.
>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> ---
> arch/arm/mach-msm/scm.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-msm/scm.c b/arch/arm/mach-msm/scm.c
> index ba57b5a..5eddf54 100644
> --- a/arch/arm/mach-msm/scm.c
> +++ b/arch/arm/mach-msm/scm.c
> @@ -264,13 +264,16 @@ u32 scm_get_version(void)
> {
> int context_id;
> static u32 version = -1;
> - register u32 r0 asm("r0") = 0x1 << 8;
> - register u32 r1 asm("r1") = (u32)&context_id;
> + register u32 r0 asm("r0");
> + register u32 r1 asm("r1");
>
> if (version != -1)
> return version;
>
> mutex_lock(&scm_lock);
> +
> + r0 = 0x1 << 8;
> + r1 = (u32)&context_id;
> asm volatile(
> __asmeq("%0", "r1")
> __asmeq("%1", "r0")
Whoa, have you seen the compiler `optimise' the original assignments
away? Since there is a use in the asm block, the definition shouldn't
be omitted. What toolchain are you using?
Will
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