[PATCH v2] coccicheck: process every source file at once

From: Jacob Keller <jacob.e.keller@intel.com>
Date: Oct 2, 2018, 20:03 UTC
Message-ID: <20181002200353.13412-1-jacob.e.keller@intel.com>

From: Jacob Keller <jacob.keller@gmail.com>

make coccicheck is used in order to apply coccinelle semantic patches, and see if any of the transformations found within contrib/coccinelle/ can be applied to the current code base.

Pass every file to a single invocation of spatch, instead of running spatch once per source file.

This reduces the time required to run make coccicheck by a significant amount of time:

Prior timing of make coccicheck
  real    6m14.090s
  user    25m2.606s
  sys     1m22.919s

New timing of make coccicheck
  real    1m36.580s
  user    7m55.933s
  sys     0m18.219s

This is nearly a 4x decrease in the time required to run make coccicheck. This is due to the overhead of restarting spatch for every file. By processing all files at once, we can amortize this startup cost across the total number of files, rather than paying it once per file.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
---
 Makefile | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index df1df9db78da..b9947f3f51ec 100644
--- a/Makefile
+++ b/Makefile
@@ -2715,10 +2715,8 @@ endif
 %.cocci.patch: %.cocci $(COCCI_SOURCES)
 	@echo '    ' SPATCH $<; \
 	ret=0; \
-	for f in $(COCCI_SOURCES); do \
-		$(SPATCH) --sp-file $< $$f $(SPATCH_FLAGS) || \
-			{ ret=$$?; break; }; \
-	done >$@+ 2>$@.log; \
+	( $(SPATCH) --sp-file $< $(COCCI_SOURCES) $(SPATCH_FLAGS) || \
+		{ ret=$$?; }; ) >$@+ 2>$@.log; \
 	if test $$ret != 0; \
 	then \
 		cat $@.log; \

-- 
2.18.0.219.gaf81d287a9da