[PATCH 4/5] cocci: make incremental compilation even faster

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Make the incremental compilation of "make coccicheck" even faster, at
the cost of losing dependency discovery for a small whitelist of *.c
files which we can't create *.o files for.

This will break obscure edge cases since e.g.:

    time make -W block-sha1/sha1.h coccicheck

Would correctly re-build before, as block-sha1/sha1.c uses
block-sha1/sha1.h, but as it and these other
$(USE_TINY_FOUND_H_SOURCES) files depended on the union of all such
headers (and more, all of $(FOUND_H_SOURCES)) the above command would
take ~10 seconds before.

As noted in the preceding commit these obscure cases were broken
before the preceding commit fixed them. I think it makes sense to make
a correctness v.s. performance trade-off here. By doing this it
becomes viable to e.g. run "make coccicheck" in the same loop that
merges various topic branches down (along with "ccache" sped-up
compilation).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index a374204aaca..9410a587fc0 100644
--- a/Makefile
+++ b/Makefile
@@ -3160,6 +3160,16 @@ COCCICHECK_OK = $(COCCICHECK:%=.build/%.ok)
 COCCICHECK_PENDING_OK = $(COCCICHECK_PENDING:%=.build/%.ok)
 COCCI_TEST_RES = $(wildcard contrib/coccinelle/tests/*.res)
 
+USE_TINY_FOUND_H_SOURCES =
+USE_TINY_FOUND_H_SOURCES += compat/%
+USE_TINY_FOUND_H_SOURCES += block-sha1/%
+USE_TINY_FOUND_H_SOURCES += ppc/%
+
+TINY_FOUND_H_SOURCES =
+TINY_FOUND_H_SOURCES += cache.h
+TINY_FOUND_H_SOURCES += git-compat-util.h
+TINY_FOUND_H_SOURCES += strbuf.h
+
 .build/contrib/coccinelle/FOUND_H_SOURCES: $(FOUND_H_SOURCES)
 	$(call mkdir_p_parent_template)
 	$(QUIET_GEN) >$@
@@ -3171,7 +3181,7 @@ define cocci-rule
 # 2 = $(2)
 COCCI_$(1:contrib/coccinelle/%.cocci=%) += .build/$(1).patch/$(2)
 .build/$(1).patch/$(2): GIT-SPATCH-DEFINES
-.build/$(1).patch/$(2): $(if $(wildcard $(3)),$(3),.build/contrib/coccinelle/FOUND_H_SOURCES)
+.build/$(1).patch/$(2): $(if $(wildcard $(3)),$(3),$(if $(filter $(USE_TINY_FOUND_H_SOURCES),$(3)),$(TINY_FOUND_H_SOURCES),.build/contrib/coccinelle/FOUND_H_SOURCES))
 .build/$(1).patch/$(2): $(1)
 .build/$(1).patch/$(2): .build/$(1).patch/% : %
 	$$(call mkdir_p_parent_template)
-- 
2.37.2.1279.g64dec4e13cf