diff mbox

Prevent unnecessary recompilation for trivial params.def changes

Message ID 55EEE0D4.7050900@mentor.com
State New
Headers show

Commit Message

Tom de Vries Sept. 8, 2015, 1:21 p.m. UTC 
[ was: Re: [RFC] Prevent unnecessary recompilation for trivial 
params.def changes ]

On 08/09/15 14:03, Andreas Schwab wrote:
> Tom de Vries <Tom_deVries@mentor.com> writes:
>
>> After a subsequent rebuild I don't see anything being rebuild. So I don't
>> observe 'continuous rebuilding'.
>
> What happens when you just touch params-list.h or params.def?
> move-if-change will leave the target untouched when unchanged (that's
> the whole point of it), so it will remain older than the dependencies.

I could reproduce the problem using these instructions, thanks.

I also found a bit "On the use of stamps" in gcc/Makefile.in, which 
explains the problem and how to fix things.

Updated patch accordingly.

OK for trunk if bootstrap succeeds?

Thanks,
- Tom

Comments

Jeff Law Sept. 8, 2015, 9:08 p.m. UTC | #1 
On 09/08/2015 07:21 AM, Tom de Vries wrote:
> [ was: Re: [RFC] Prevent unnecessary recompilation for trivial
> params.def changes ]
>
> On 08/09/15 14:03, Andreas Schwab wrote:
>> Tom de Vries <Tom_deVries@mentor.com> writes:
>>
>>> After a subsequent rebuild I don't see anything being rebuild. So I
>>> don't
>>> observe 'continuous rebuilding'.
>>
>> What happens when you just touch params-list.h or params.def?
>> move-if-change will leave the target untouched when unchanged (that's
>> the whole point of it), so it will remain older than the dependencies.
>
> I could reproduce the problem using these instructions, thanks.
>
> I also found a bit "On the use of stamps" in gcc/Makefile.in, which
> explains the problem and how to fix things.
>
> Updated patch accordingly.
>
> OK for trunk if bootstrap succeeds?
Yes.
jeff
diff mbox

Patch

Prevent unnecessary recompilation for trivial params.def changes

2015-09-08  Tom de Vries  <tom@codesourcery.com>

	* Makefile.in (generated_files): Add params.list.
	(params.list, s-params.list): Add rule.
	* params.h (enum compiler_param): Include params-list.h.  Move define
	DEFPARAM, include params.def and undef DEFPARAM ...
	* params-list.h: ... here.  New file.
---
 gcc/Makefile.in   | 8 +++++++-
 gcc/params-list.h | 4 ++++
 gcc/params.h      | 5 +----
 3 files changed, 12 insertions(+), 5 deletions(-)
 create mode 100644 gcc/params-list.h

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 3d1c1e5..b495bd2 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -2415,7 +2415,7 @@  generated_files = config.h tm.h $(TM_P_H) $(TM_H) multilib.h \
        $(ALL_GTFILES_H) gtype-desc.c gtype-desc.h gcov-iov.h \
        options.h target-hooks-def.h insn-opinit.h \
        common/common-target-hooks-def.h pass-instances.def \
-       c-family/c-target-hooks-def.h
+       c-family/c-target-hooks-def.h params.list
 
 #
 # How to compile object files to run on the build machine.
@@ -3236,6 +3236,12 @@  installdirs:
 	$(mkinstalldirs) $(DESTDIR)$(man1dir)
 	$(mkinstalldirs) $(DESTDIR)$(man7dir)
 
+params.list: s-params.list; @true
+s-params.list: $(srcdir)/params-list.h $(srcdir)/params.def
+	$(CPP) $(srcdir)/params-list.h | sed 's/^#.*//;/^$$/d' > tmp-params.list
+	$(SHELL) $(srcdir)/../move-if-change tmp-params.list params.list
+	$(STAMP) s-params.list
+
 PLUGIN_HEADERS = $(TREE_H) $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
   toplev.h $(DIAGNOSTIC_CORE_H) $(BASIC_BLOCK_H) $(HASH_TABLE_H) \
   tree-ssa-alias.h $(INTERNAL_FN_H) gimple-fold.h tree-eh.h gimple-expr.h \
diff --git a/gcc/params-list.h b/gcc/params-list.h
new file mode 100644
index 0000000..49301d2
--- /dev/null
+++ b/gcc/params-list.h
@@ -0,0 +1,4 @@ 
+#define DEFPARAM(enumerator, option, nocmsgid, default, min, max) \
+  enumerator,
+#include "params.def"
+#undef DEFPARAM
diff --git a/gcc/params.h b/gcc/params.h
index f53426d..9f7618a 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -81,10 +81,7 @@  extern void set_param_value (const char *name, int value,
 
 enum compiler_param
 {
-#define DEFPARAM(enumerator, option, nocmsgid, default, min, max) \
-  enumerator,
-#include "params.def"
-#undef DEFPARAM
+#include "params.list"
   LAST_PARAM
 };
 
-- 
1.9.1