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Re: [Xen-devel] [PATCH] xen/arm: Workaround clang/armclang support for register allocation
Hi,
Ping?
Cheers,
On 17/02/2020 22:20, Julien Grall wrote:
Clang 8.0 (see [1]) and by extent some of the version of armclang does
not support register allocation using the syntax rN.
Thankfully, both GCC [2] and clang are able to support the xN syntax for
Arm64. Introduce a new macro ASM_REG() and use in common code for
register allocation.
[1] https://reviews.llvm.org/rL328829
[2] https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html
Cc: Andrii Anisov <andrii_anisov@xxxxxxxx>
Signed-off-by: Julien Grall <julien@xxxxxxx>
---
xen/include/asm-arm/asm_defns.h | 8 +++-
xen/include/asm-arm/smccc.h | 74 ++++++++++++++++-----------------
2 files changed, 44 insertions(+), 38 deletions(-)
diff --git a/xen/include/asm-arm/asm_defns.h b/xen/include/asm-arm/asm_defns.h
index b4fbcdae1d..29a9dbb002 100644
--- a/xen/include/asm-arm/asm_defns.h
+++ b/xen/include/asm-arm/asm_defns.h
@@ -7,11 +7,17 @@
#endif
#include <asm/processor.h>
-/* For generic assembly code: use macros to define operand sizes. */
+/* Macros for generic assembly code */
#if defined(CONFIG_ARM_32)
# define __OP32
+# define ASM_REG(index) asm("r" # index)
#elif defined(CONFIG_ARM_64)
# define __OP32 "w"
+/*
+ * Clang < 8.0 doesn't support register alllocation using the syntax rN.
+ * See https://reviews.llvm.org/rL328829.
+ */
+# define ASM_REG(index) asm("x" # index)
#else
# error "unknown ARM variant"
#endif
diff --git a/xen/include/asm-arm/smccc.h b/xen/include/asm-arm/smccc.h
index 126399dd70..9d94beb3df 100644
--- a/xen/include/asm-arm/smccc.h
+++ b/xen/include/asm-arm/smccc.h
@@ -120,59 +120,59 @@ struct arm_smccc_res {
#define __constraint_read_6 __constraint_read_5, "r" (r6)
#define __constraint_read_7 __constraint_read_6, "r" (r7)
-#define __declare_arg_0(a0, res) \
- struct arm_smccc_res *___res = res; \
- register unsigned long r0 asm("r0") = (uint32_t)a0;\
- register unsigned long r1 asm("r1"); \
- register unsigned long r2 asm("r2"); \
- register unsigned long r3 asm("r3")
-
-#define __declare_arg_1(a0, a1, res) \
- typeof(a1) __a1 = a1; \
- struct arm_smccc_res *___res = res; \
- register unsigned long r0 asm("r0") = (uint32_t)a0;\
- register unsigned long r1 asm("r1") = __a1; \
- register unsigned long r2 asm("r2"); \
- register unsigned long r3 asm("r3")
-
-#define __declare_arg_2(a0, a1, a2, res) \
- typeof(a1) __a1 = a1; \
- typeof(a2) __a2 = a2; \
- struct arm_smccc_res *___res = res; \
- register unsigned long r0 asm("r0") = (uint32_t)a0;\
- register unsigned long r1 asm("r1") = __a1; \
- register unsigned long r2 asm("r2") = __a2; \
- register unsigned long r3 asm("r3")
-
-#define __declare_arg_3(a0, a1, a2, a3, res) \
- typeof(a1) __a1 = a1; \
- typeof(a2) __a2 = a2; \
- typeof(a3) __a3 = a3; \
- struct arm_smccc_res *___res = res; \
- register unsigned long r0 asm("r0") = (uint32_t)a0;\
- register unsigned long r1 asm("r1") = __a1; \
- register unsigned long r2 asm("r2") = __a2; \
- register unsigned long r3 asm("r3") = __a3
+#define __declare_arg_0(a0, res) \
+ struct arm_smccc_res *___res = res; \
+ register unsigned long r0 ASM_REG(0) = (uint32_t)a0; \
+ register unsigned long r1 ASM_REG(1); \
+ register unsigned long r2 ASM_REG(2); \
+ register unsigned long r3 ASM_REG(3)
+
+#define __declare_arg_1(a0, a1, res) \
+ typeof(a1) __a1 = a1; \
+ struct arm_smccc_res *___res = res; \
+ register unsigned long r0 ASM_REG(0) = (uint32_t)a0; \
+ register unsigned long r1 ASM_REG(1) = __a1; \
+ register unsigned long r2 ASM_REG(2); \
+ register unsigned long r3 ASM_REG(3)
+
+#define __declare_arg_2(a0, a1, a2, res) \
+ typeof(a1) __a1 = a1; \
+ typeof(a2) __a2 = a2; \
+ struct arm_smccc_res *___res = res; \
+ register unsigned long r0 ASM_REG(0) = (uint32_t)a0; \
+ register unsigned long r1 ASM_REG(1) = __a1; \
+ register unsigned long r2 ASM_REG(2) = __a2; \
+ register unsigned long r3 ASM_REG(3)
+
+#define __declare_arg_3(a0, a1, a2, a3, res) \
+ typeof(a1) __a1 = a1; \
+ typeof(a2) __a2 = a2; \
+ typeof(a3) __a3 = a3; \
+ struct arm_smccc_res *___res = res; \
+ register unsigned long r0 ASM_REG(0) = (uint32_t)a0; \
+ register unsigned long r1 ASM_REG(1) = __a1; \
+ register unsigned long r2 ASM_REG(2) = __a2; \
+ register unsigned long r3 ASM_REG(3) = __a3
#define __declare_arg_4(a0, a1, a2, a3, a4, res) \
typeof(a4) __a4 = a4; \
__declare_arg_3(a0, a1, a2, a3, res); \
- register unsigned long r4 asm("r4") = __a4
+ register unsigned long r4 ASM_REG(4) = __a4
#define __declare_arg_5(a0, a1, a2, a3, a4, a5, res) \
typeof(a5) __a5 = a5; \
__declare_arg_4(a0, a1, a2, a3, a4, res); \
- register typeof(a5) r5 asm("r5") = __a5
+ register typeof(a5) r5 ASM_REG(5) = __a5
#define __declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res) \
typeof(a6) __a6 = a6; \
__declare_arg_5(a0, a1, a2, a3, a4, a5, res); \
- register typeof(a6) r6 asm("r6") = __a6
+ register typeof(a6) r6 ASM_REG(6) = __a6
#define __declare_arg_7(a0, a1, a2, a3, a4, a5, a6, a7, res) \
typeof(a7) __a7 = a7; \
__declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res); \
- register typeof(a7) r7 asm("r7") = __a7
+ register typeof(a7) r7 ASM_REG(7) = __a7
#define ___declare_args(count, ...) __declare_arg_ ## count(__VA_ARGS__)
#define __declare_args(count, ...) ___declare_args(count, __VA_ARGS__)
--
Julien Grall
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