Simplify subdirectory makefiles, and be more robust by checking that they define the appropriate variables.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@93714 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 76 insertions, 9 deletions

diff --git a/make/config.mk b/make/config.mk
index 485119186..903424d01 100644
--- a/make/config.mk
+++ b/make/config.mk
@@ -11,7 +11,8 @@ ProjObjRoot := $(ProjSrcRoot)
 Configs := Debug Release Profile
 
 # The full list of architectures we support.
-Archs := i386 ppc x86_64 armv6 armv7
+Archs := i386 ppc x86_64
+# armv6 armv7
 
 # If TargetArch is defined, only build for that architecture (and don't use
 # -arch).
@@ -66,7 +67,7 @@ LIPO := lipo
 CP := cp
 
 VERBOSE := 0
-DEBUGMAKE := 0
+DEBUGMAKE :=
 
 ###
 # Automatic and derived variables.
diff --git a/make/subdir.mk b/make/subdir.mk
index 81e295820..ccde0dc8d 100644
--- a/make/subdir.mk
+++ b/make/subdir.mk
@@ -1,13 +1,20 @@
 # This file is intended to be included from each subdirectory makefile.
+#
+# Subdirectory makefiles must define:
+#   SubDirs - The subdirectories to traverse.
+#   ObjNames - The objects available in that directory.
+#   Target - The library configuration the objects should go in (Generic or
+#            Optimized)
+#   Dependencies - Any dependences for the object files.
+#
+# Subdirectory makefiles may define:
+#   OnlyArchs - Only build the objects for the listed archs.
+#   OnlyConfigs - Only build the objects for the listed configurations.
 
 ifeq ($(Dir),)
   $(error "No Dir variable defined.")
 endif
 
-ifeq ($(DEBUGMAKE),1)
-  $(info MAKE: $(Dir): Processing subdirectory)
-endif
-
 # Expand template for each configuration and architecture.
 #
 # FIXME: This level of logic should be in primary Makefile?
@@ -35,13 +42,60 @@ $(foreach config,$(ConfigsToTraverse), \
 ###
 # Include child makefile fragments
 
+# The list of variables which are intended to be overridden in a subdirectory
+# makefile.
+RequiredSubdirVariables := SubDirs ObjNames Target Dependencies
+OptionalSubdirVariables := OnlyArchs OnlyConfigs
+
+# Template: subdir_traverse_template subdir
+define subdir_traverse_template
+$(call Set,Dir,$(1))
+ifneq ($(DEBUGMAKE),)
+  $$(info MAKE: $(Dir): Processing subdirectory)
+endif
+
+# Reset subdirectory specific variables to sentinel value.
+$$(foreach var,$$(RequiredSubdirVariables) $$(OptionalSubdirVariables),\
+  $$(call Set,$$(var),UNDEFINED))
+
+# Get the subdirectory variables.
+include $(1)/Makefile.mk
+
+ifeq ($(DEBUGMAKE),2)
+$$(foreach var,$(RequiredSubdirVariables) $(OptionalSubdirVariables),\
+  $$(if $$(call strneq UNDEFINED,$$($$(var))), \
+	$$(info MAKE: $(Dir): $$(var) is defined), \
+	$$(info MAKE: $(Dir): $$(var) is undefined)))
+endif
+
+# Check for undefined required variables, and unset sentinel value from optional
+# variables.
+$$(foreach var,$(RequiredSubdirVariables),\
+  $$(if $$(call strneq UNDEFINED,$$($$(var))), \
+	$$(error $(Dir): variable '$$(var)' was not undefined)))
+$$(foreach var,$(OptionalSubdirVariables),\
+  $$(if $$(call strneq UNDEFINED,$$($$(var))),, \
+	$$(call Set,$$(var),)))
+
+# Recurse.
+include make/subdir.mk
+
+# Restore directory variable.
+$$(call Set,Dir,$(1))
+
+ifneq ($(DEBUGMAKE),)
+  $$(info MAKE: $$(Dir): Done processing subdirectory)
+endif
+endef
+
 # Evaluate this now so we do not have to worry about order of evaluation.
 SubDirsList := $(SubDirs:%=$(Dir)/%)
 ifeq ($(SubDirsList),)
 else
-  ifeq ($(DEBUGMAKE),1)
+  ifneq ($(DEBUGMAKE),)
     $(info MAKE: Descending into subdirs: $(SubDirsList))
   endif
-  $(foreach subdir,$(SubDirsList),$(eval include $(subdir)/Makefile.mk))
-endif
 
+  $(foreach subdir,$(SubDirsList),\
+	$(eval $(call subdir_traverse_template,$(subdir))))
+endif
diff --git a/make/util.mk b/make/util.mk
index 4f6579084..2ce9a46a2 100644
--- a/make/util.mk
+++ b/make/util.mk
@@ -3,6 +3,18 @@
 ###
 # Utility functions
 
+# Function: streq LHS RHS
+#
+# Return "true" if LHS == RHS, otherwise "".
+#
+# LHS == RHS <=> (LHS subst RHS is empty) and (RHS subst LHS is empty)
+streq = $(if $(1),$(if $(subst $(1),,$(2))$(subst $(2),,$(1)),,true),$(if $(2),,true))
+
+# Function: strneq LHS RHS
+#
+# Return "true" if LHS != RHS, otherwise "".
+strneq = $(if $(call streq,$(1),$(2)),,true)
+
 # Function: Set variable value
 #
 # Set the given make variable to the given value.