Make generation of dependency files more efficient when possible

When building with GNU C, clang or VMS C, it's more efficient to
generate dependency file and object file in one call rather than two.
Have the dependency output in a temporary file and compare it with the
previous one if available to see if replacement is waranted, thereby
avoiding unnecessary reconstruction of Makefile / descrip.mms.

Github issue #750

Reviewed-by: Rich Salz <rsalz@openssl.org>

diff --git a/Configurations/descrip.mms.tmpl b/Configurations/descrip.mms.tmpl
index eb60b4ad814ce0b037749cdf8fd97e02bf1ae2b5..b7e047ba7c4d4cd1f020542e9c6a128144b702b3 100644 (file)
--- a/Configurations/descrip.mms.tmpl
+++ b/Configurations/descrip.mms.tmpl
@@ -435,19 +435,15 @@ configdata.pm : {- sourcefile("Configurations", "descrip.mms.tmpl") -} $(SRCDIR)
       my $after = $unified_info{after}->{$obj.".OBJ"} || "\@ !";
 
       return <<"EOF";
-$obj.MMS : $deps
+$obj.OBJ : $deps
         ${before}
         SET DEFAULT $forward
-        \$(CC) \$(CFLAGS)${incs} /MMS=(FILE=${objd}${objn}.MMS,TARGET=$obj.OBJ) /NOOBJECT $srcs
-        SET DEFAULT $backward
-        ${after}
-        - PURGE $obj.MMS
-$obj.OBJ : $obj.MMS
-        ${before}
-        SET DEFAULT $forward
-        \$(CC) \$(CFLAGS)${incs} /OBJECT=${objd}${objn}.OBJ /REPOSITORY=$backward $srcs
+        \$(CC) \$(CFLAGS)${incs} /MMS=(FILE=${objd}${objn}.tmp-MMS,TARGET=$obj.OBJ) /OBJECT=${objd}${objn}.OBJ /REPOSITORY=$backward $srcs
         SET DEFAULT $backward
         ${after}
+        \@ PIPE ( \$(PERL) -e "use File::Compare qw/compare_text/; my \$x = compare_text(""$obj.MMS"",""$obj.tmp-MMS""); exit(0x10000000 + (\$x == 0));" || -
+                 RENAME $obj.tmp-MMS $obj.mms )
+        \@ IF F\$SEARCH("$obj.tmp-MMS") .NES. "" THEN DELETE $obj.tmp-MMS;*
         - PURGE $obj.OBJ
 EOF
   }

diff --git a/Configurations/unix-Makefile.tmpl b/Configurations/unix-Makefile.tmpl
index b9fc5f87e7ea645b2787a702f2496d6f01f200e4..cff0023a3e310416a23508cf277076c0bca1f26c 100644 (file)
--- a/Configurations/unix-Makefile.tmpl
+++ b/Configurations/unix-Makefile.tmpl
@@ -847,11 +847,12 @@ $obj$objext: $obj$depext
 EOF
       }
       return <<"EOF";
-$obj$depext: $deps
-       \$(CC) \$(CFLAGS) $ecflags$incs -MM -MF \$\@ -MQ $obj$objext $srcs
-       touch \$\@
-$obj$objext: $obj$depext
-       \$(CC) \$(CFLAGS) $ecflags$incs -c -o \$\@ $srcs
+$obj$objext: $deps
+       \$(CC) \$(CFLAGS) $ecflags$incs -MMD -MF $obj$depext.tmp -MT \$\@ -c -o \$\@ $srcs
+       \@touch $obj$depext.tmp
+       \@if ! cmp $obj$depext.tmp $obj$depext > /dev/null 2> /dev/null; then \\
+               mv $obj$depext.tmp $obj$depext; \\
+       fi
 EOF
   }
   # On Unix, we build shlibs from static libs, so we're ignoring the