[PATCH v1] xen/riscv: improve check-extension() macro

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Now, the check-extension() macro has 1 argument instead of 2.
This change helps to reduce redundancy around usage of extensions
name (in the case of the zbb extension, the name was used 3 times).

To implement this, a new variable was introduced:
  <extension name>-insn
which represents the instruction support that is being checked.

Additionally, zbb-insn is updated to use $(comma) instead of ",".

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/riscv/arch.mk | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/xen/arch/riscv/arch.mk b/xen/arch/riscv/arch.mk
index dd242c91d1..17827c302c 100644
--- a/xen/arch/riscv/arch.mk
+++ b/xen/arch/riscv/arch.mk
@@ -13,12 +13,21 @@ riscv-generic-flags := $(riscv-abi-y) 
-march=$(riscv-march-y)
 
 # check-extension: Check whether extenstion is supported by a compiler and
 #                  an assembler.
-# Usage: $(call check-extension,extension_name,"instr")
-check-extension = $(call as-insn,$(CC) $(riscv-generic-flags)_$(1),$(2),_$(1))
-
-zbb-insn := "andn t0, t0, t0"
-zbb := $(call check-extension,zbb,$(zbb-insn))
-zihintpause := $(call check-extension,zihintpause,"pause")
+# Usage: $(call check-extension,extension_name).
+#        it should be defined variable with following name:
+#          <extension name>-insn := "insn"
+#        which represents an instruction of extension support of which is
+#        going to be checked.
+define check-extension =
+$(eval $(1) := \
+       $(call as-insn,$(CC) $(riscv-generic-flags)_$(1),$(value 
$(1)-insn),_$(1)))
+endef
+
+zbb-insn := "andn t0$(comma)t0$(comma)t0"
+$(call check-extension,zbb)
+
+zihintpause-insn := "pause"
+$(call check-extension,zihintpause)
 
 extensions := $(zbb) $(zihintpause)
 
-- 
2.44.0