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| author | Blue Swirl <blauwirbel@gmail.com> | 2010-10-02 14:28:12 +0000 |
|---|---|---|
| committer | Blue Swirl <blauwirbel@gmail.com> | 2010-10-02 14:28:12 +0000 |
| commit | a82cdd58fd9ffa8c651f51de8d855f6baf708681 (patch) | |
| tree | c07111dd003a2875da57d33246d350223868ac38 /Makefile | |
| parent | 904fe1fbd10388f384c9930fa2d8a25113b7e7aa (diff) | |
| download | qemu-a82cdd58fd9ffa8c651f51de8d855f6baf708681.zip | |
trace: avoid unnecessary recompilation if nothing changed
Add logic to detect changes in generated files. If the old
and new files are identical, don't touch the generated file.
This avoids a lot of churn since many files depend on trace.h.
Based on suggestion by Paolo Bonzini.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 14 |
1 files changed, 9 insertions, 5 deletions
@@ -106,11 +106,15 @@ ui/vnc.o: QEMU_CFLAGS += $(VNC_TLS_CFLAGS) bt-host.o: QEMU_CFLAGS += $(BLUEZ_CFLAGS) -trace.h: $(SRC_PATH)/trace-events config-host.mak - $(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -h < $< > $@," GEN $@") - -trace.c: $(SRC_PATH)/trace-events config-host.mak - $(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -c < $< > $@," GEN $@") +trace.h: trace.h-timestamp +trace.h-timestamp: $(SRC_PATH)/trace-events config-host.mak + $(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -h < $< > $@," GEN trace.h") + @cmp -s $@ trace.h || cp $@ trace.h + +trace.c: trace.c-timestamp +trace.c-timestamp: $(SRC_PATH)/trace-events config-host.mak + $(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -c < $< > $@," GEN trace.c") + @cmp -s $@ trace.c || cp $@ trace.c trace.o: trace.c $(GENERATED_HEADERS) |