[Xen-devel] [PATCH for-4.13 4/6] xen/arm: cpufeature: Match register size with value size in cpus_have_const_cap

[Julien Grall <julien.grall@xxxxxxx>]

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.grall@xxxxxxx>

---
    Changes in v2:
        - Use !! per Stefano's request
---
 xen/include/asm-arm/cpufeature.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index c2c8f3417c..4c5ff6e8ac 100644
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -67,14 +67,14 @@ 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",     \
                                   num)              \
                       : "=r" (__ret));              \
                                                     \
-        unlikely(__ret);                            \
+        unlikely(!!__ret);                          \
         })
 
 static inline void cpus_set_cap(unsigned int num)
-- 
2.11.0


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