[Mesa-dev] [PATCH 2/4] anv: use cache uuid based on the build timestamp.

[Eric Engestrom]

On Wed, Jun 22, 2016 at 04:57:39PM +0100, Eric Engestrom wrote:
> On Wed, Jun 22, 2016 at 01:04:41PM +0100, Emil Velikov wrote:
> > From: Emil Velikov <emil.velikov at collabora.com>

[...]

> > diff --git a/src/intel/vulkan/Makefile.am b/src/intel/vulkan/Makefile.am
> > index 4d9ff90..8332ae5 100644
> > --- a/src/intel/vulkan/Makefile.am
> > +++ b/src/intel/vulkan/Makefile.am
> > @@ -131,7 +131,20 @@ anv_entrypoints.c : anv_entrypoints_gen.py $(vulkan_include_HEADERS)
> >  	$(AM_V_GEN) cat $(vulkan_include_HEADERS) |\
> >  	$(PYTHON2) $(srcdir)/anv_entrypoints_gen.py code > $@
> >  
> > -BUILT_SOURCES = $(VULKAN_GENERATED_FILES)
> > +
> > +.PHONY: anv_timestamp.h.tmp
> > +anv_timestamp.h.tmp:
> > +	$(AM_V_GEN) echo "#define ANV_TIMESTAMP `date +%s`" > $@
> > +
> > +anv_timestamp.h: anv_timestamp.h.tmp
> > +	@echo "Updating anv_timestamp.h"
> > +	@if ! cmp -s anv_timestamp.h.tmp anv_timestamp.h; then \
> > +		mv anv_timestamp.h.tmp anv_timestamp.h ;\
> > +	else \
> > +		rm anv_timestamp.h.tmp ;\
> > +	fi
> 
> For the else branch to be taken, the target would have to be generated
> twice within the same second, and I don't see why we would want to avoid
> modifying anv_timestamp.h's timestamp in this case, since that would be
> the only thing that would be changed, and said timestamp would be within
> the same second anyway.
> I suggest to drop the `if` and unconditionally do the move.
> 
> Since this wouldn't change the behaviour anyway, with or without my
> suggestion this patch is:
> Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>


Actually, the .tmp target isn't needed either, you just have to tag the
.h target as PHONY:

  .PHONY: anv_timestamp.h
  anv_timestamp.h:
  	@echo "Updating anv_timestamp.h"
  	$(AM_V_GEN) echo "#define ANV_TIMESTAMP `date +%s`" > $@

Unless I'm missing something, this has the exact same behaviour.