On 4/17/19 9:29 PM, Stefano Stabellini wrote:
On Wed, 27 Mar 2019, Julien Grall wrote:
Clang is pickier than GCC for the register size in asm statement. It
expects the register size to match the value size.
The asm statement expects a 32-bit (resp. 64-bit) value on Arm32
(resp. Arm64) whereas the value is a boolean (Clang consider to be
32-bit).
It would be possible to impose 32-bit register for both architecture
but this require the code to use __OP32. However, it does no really
improve the assembly generated. Instead, replace switch the variable to
use register_t.
Signed-off-by: Julien Grall <julien.gr...@arm.com>
---
xen/include/asm-arm/cpufeature.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index c2c8f3417c..d06f09ecfa 100644
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -67,7 +67,7 @@ static inline bool cpus_have_cap(unsigned int num)
/* System capability check for constant cap */
#define cpus_have_const_cap(num) ({ \
- bool __ret; \
+ register_t __ret; \
\
asm volatile (ALTERNATIVE("mov %0, #0", \
"mov %0, #1", \
As per the previous one, this is fine, but could you also change the
last statement below to unlikely(!!__ret);
As per the previous one, the current code is valid. Please justify why
!! is necessary.
Cheers,
--
Julien Grall
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