[PATCH v5 05/11] rules.mak: Add base-arch() rule

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Add a rule to return the base architecture for a QEMU target.

The current list of TARGET_BASE_ARCH is:

  $ git grep  TARGET_BASE_ARCH configure
  configure:7785:TARGET_BASE_ARCH=""
  configure:7795:    TARGET_BASE_ARCH=i386
  configure:7813:    TARGET_BASE_ARCH=arm
  configure:7846:    TARGET_BASE_ARCH=mips
  configure:7854:    TARGET_BASE_ARCH=mips
  configure:7864:    TARGET_BASE_ARCH=openrisc
  configure:7871:    TARGET_BASE_ARCH=ppc
  configure:7879:    TARGET_BASE_ARCH=ppc
  configure:7887:    TARGET_BASE_ARCH=ppc
  configure:7894:    TARGET_BASE_ARCH=riscv
  configure:7900:    TARGET_BASE_ARCH=riscv
  configure:7920:    TARGET_BASE_ARCH=sparc
  configure:7925:    TARGET_BASE_ARCH=sparc

The rule can be tested calling 'print-base-arch-$TARGET':

  $ make \
      print-base-arch-openrisc \
      print-base-arch-aarch64_be \
      print-base-arch-x86_64 \
      print-base-arch-mips64el \
      print-base-arch-ppc64 \
      print-base-arch-riscv64
  openrisc=openrisc
  aarch64_be=arm
  x86_64=i386
  mips64el=mips
  ppc64=ppc
  riscv64=riscv

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v5:
- risc -> riscv (rth)
- use strequal (rth)
- add microblaze/sh4/xtensa
v4:
- use startwith()
- fix openrisc (rth)
---
 rules.mak | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/rules.mak b/rules.mak
index ccc1c49604..907f9aca91 100644
--- a/rules.mak
+++ b/rules.mak
@@ -452,3 +452,38 @@ atomic = $(eval $1: $(call sentinel,$1) ; @:) \
 
 print-%:
 	@echo '$*=$($*)'
+
+# base-arch
+# Usage: $(call base-arch, target)
+#
+# @target: the target architecture.
+#
+# This macro will return the base architecture for a target.
+#
+# As example, $(call base-arch, aarch64) returns 'arm'.
+base-arch = $(strip \
+		$(if $(call startwith,aarch64,$1),arm,\
+		  $(if $(call startwith,arm,$1),arm,\
+		    $(if $(call startwith,microblaze,$1),microblaze,\
+		      $(if $(call startwith,mips,$1),mips,\
+		        $(if $(call startwith,ppc,$1),ppc,\
+		          $(if $(call startwith,riscv,$1),riscv,\
+		            $(if $(call startwith,sh4,$1),sh4,\
+		              $(if $(call startwith,sparc,$1),sparc,\
+		                $(if $(call startwith,xtensa,$1),xtensa,\
+		                  $(if $(call strequal,x86_64,$1),i386,\
+		                    $1\
+		                   )\
+		                 )\
+		               )\
+		             )\
+		           )\
+		         )\
+		       )\
+		     )\
+		   )\
+		 )\
+		)
+
+print-base-arch-%:
+	@echo '$*=$(call base-arch,$*)'
-- 
2.21.3