From fb72a97df9222be61ec582ba7b1e9ce496b65e3e Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Wed, 14 Aug 2013 02:50:25 -0400
Subject: [PATCH] rework makefile subarch logic to allow shared files

instead of subarchs getting their own .s files which are used directly
by the makefile to replace the .c file, they now must provide a .sub
file whose contents are a pathname, relative to the location of the
.sub file, which will substitute for the .c file. essentially these
files are acting as symbolic links, but implemented as text files.
---
 Makefile | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 9206ca02..33c2de1b 100644
--- a/Makefile
+++ b/Makefile
@@ -90,8 +90,16 @@ $(OPTIMIZE_SRCS:%.c=%.o) $(OPTIMIZE_SRCS:%.c=%.lo): CFLAGS += -O3
 MEMOPS_SRCS = src/string/memcpy.c src/string/memmove.c src/string/memcmp.c src/string/memset.c
 $(MEMOPS_SRCS:%.c=%.o) $(MEMOPS_SRCS:%.c=%.lo): CFLAGS += $(CFLAGS_MEMOPS)
 
-%.o: $(ARCH)$(ASMSUBARCH)/%.s
-	$(CC) $(CFLAGS_ALL_STATIC) -c -o $@ $<
+# This incantation ensures that changes to any subarch asm files will
+# force the corresponding object file to be rebuilt, even if the implicit
+# rule below goes indirectly through a .sub file.
+define mkasmdep
+$(dir $(patsubst %/,%,$(dir $(1))))$(notdir $(1:.s=.o)): $(1)
+endef
+$(foreach s,$(wildcard src/*/$(ARCH)*/*.s),$(eval $(call mkasmdep,$(s))))
+
+%.o: $(ARCH)$(ASMSUBARCH)/%.sub
+	$(CC) $(CFLAGS_ALL_STATIC) -c -o $@ $(dir $<)$(shell cat $<)
 
 %.o: $(ARCH)/%.s
 	$(CC) $(CFLAGS_ALL_STATIC) -c -o $@ $<
@@ -99,8 +107,8 @@ $(MEMOPS_SRCS:%.c=%.o) $(MEMOPS_SRCS:%.c=%.lo): CFLAGS += $(CFLAGS_MEMOPS)
 %.o: %.c $(GENH) $(IMPH)
 	$(CC) $(CFLAGS_ALL_STATIC) -c -o $@ $<
 
-%.lo: $(ARCH)$(ASMSUBARCH)/%.s
-	$(CC) $(CFLAGS_ALL_SHARED) -c -o $@ $<
+%.lo: $(ARCH)$(ASMSUBARCH)/%.sub
+	$(CC) $(CFLAGS_ALL_SHARED) -c -o $@ $(dir $<)$(shell cat $<)
 
 %.lo: $(ARCH)/%.s
 	$(CC) $(CFLAGS_ALL_SHARED) -c -o $@ $<