[AArch64] Use move-if-change for aarch64-tune.md

If aarch64-tune.md was older than gentune.sh or aarch64-cores.def,
we'd try to overwrite it even if the current contents were correct.
This could cause problems with read-only source directories and
could cause spurious copying for rsync --archive.

2020-01-06  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/t-aarch64 ($(srcdir)/config/aarch64/aarch64-tune.md):
	Depend on...
	(s-aarch64-tune-md): ...this new stamp file.  Pipe the new contents
	to a temporary file and use move-if-change to update the real
	file where necessary.

From-SVN: r279900

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 520562a..820a86f 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,13 @@
 2020-01-06  Richard Sandiford  <richard.sandiford@arm.com>
 
+       * config/aarch64/t-aarch64 ($(srcdir)/config/aarch64/aarch64-tune.md):
+       Depend on...
+       (s-aarch64-tune-md): ...this new stamp file.  Pipe the new contents
+       to a temporary file and use move-if-change to update the real
+       file where necessary.
+
+2020-01-06  Richard Sandiford  <richard.sandiford@arm.com>
+
        * config/aarch64/aarch64-sve.md (@aarch64_sel_dup<mode>): Use Upl
        rather than Upa for CPY /M.
 

diff --git a/gcc/config/aarch64/t-aarch64 b/gcc/config/aarch64/t-aarch64
index ed250ea..475d5c5 100644 (file)
--- a/gcc/config/aarch64/t-aarch64
+++ b/gcc/config/aarch64/t-aarch64
@@ -24,11 +24,15 @@ OPTIONS_H_EXTRA += $(srcdir)/config/aarch64/aarch64-cores.def \
                   $(srcdir)/config/aarch64/aarch64-fusion-pairs.def \
                   $(srcdir)/config/aarch64/aarch64-tuning-flags.def
 
-$(srcdir)/config/aarch64/aarch64-tune.md: $(srcdir)/config/aarch64/gentune.sh \
+$(srcdir)/config/aarch64/aarch64-tune.md: s-aarch64-tune-md; @true
+s-aarch64-tune-md: $(srcdir)/config/aarch64/gentune.sh \
        $(srcdir)/config/aarch64/aarch64-cores.def
        $(SHELL) $(srcdir)/config/aarch64/gentune.sh \
                $(srcdir)/config/aarch64/aarch64-cores.def > \
+               tmp-aarch64-tune.md
+       $(SHELL) $(srcdir)/../move-if-change tmp-aarch64-tune.md \
                $(srcdir)/config/aarch64/aarch64-tune.md
+       $(STAMP) s-aarch64-tune-md
 
 aarch64-builtins.o: $(srcdir)/config/aarch64/aarch64-builtins.c $(CONFIG_H) \
   $(SYSTEM_H) coretypes.h $(TM_H) \