* Don't print out HOW we are running Flex unless in verbose mode. We …

…already

  hide the bison command line.
* If running flex or bison gives us the files we already have, don't overwrite
  the ones we have, which cause unnecessary compilation.  I demand the ability
  to make meaningless changes without penalty!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7571 91177308-0d34-0410-b5e6-96231b3b80d8

Makefile.common

@@ -766,19 +766,26 @@ YACC_OUTPUT = $(addprefix $(YACC_FILES:%.y=%), .h .cpp .output)
 # FIXME.  (f.e. char Buffer[10000]; )
 #
 %.cpp: %.l
-	$(FLEX) -t $< | $(SED) '/^find_rule/d' | \
+	@echo Flex\'ing $<...
+	$(VERB) $(FLEX) -t $< | $(SED) '/^find_rule/d' | \
                      $(SED) 's/void yyunput/inline void yyunput/' | \
           $(SED) 's/void \*yy_flex_realloc/inline void *yy_flex_realloc/' | \
-          $(SED) 's/#define YY_BUF_SIZE 16384/#define YY_BUF_SIZE (16384*64)/' > $@
+          $(SED) 's/#define YY_BUF_SIZE 16384/#define YY_BUF_SIZE (16384*64)/' \
+              > $@.tmp
+	$(VERB) diff -q $@ $@.tmp || ${MV} -f $@.tmp $@
+	@# remove the output of flex if it didn't get moved over...
+	@rm -f $@.tmp
 
 # Rule for building the bison parsers...
 %.c: %.y     # Cancel built-in rules for yacc
 %.h: %.y     # Cancel built-in rules for yacc
 %.cpp %.h : %.y
 	@echo Bison\'ing $<...
 	$(VERB) $(BISON) -v -d -p $(<:%Parser.y=%) $*.y
-	$(VERB) ${MV} -f $*.tab.c $*.cpp
-	$(VERB) ${MV} -f $*.tab.h $*.h
+	$(VERB) diff -q $*.tab.c $*.cpp || ${MV} -f $*.tab.c $*.cpp
+	$(VERB) diff -q $*.tab.h $*.h || ${MV} -f $*.tab.h $*.h
+	@# If the files were not updated, don't leave them lying around...
+	@rm -f $*.tab.c $*.tab.h
 
 # To create the directories...
 %/.dir:

Makefile.rules

@@ -766,19 +766,26 @@ YACC_OUTPUT = $(addprefix $(YACC_FILES:%.y=%), .h .cpp .output)
 # FIXME.  (f.e. char Buffer[10000]; )
 #
 %.cpp: %.l
-	$(FLEX) -t $< | $(SED) '/^find_rule/d' | \
+	@echo Flex\'ing $<...
+	$(VERB) $(FLEX) -t $< | $(SED) '/^find_rule/d' | \
                      $(SED) 's/void yyunput/inline void yyunput/' | \
           $(SED) 's/void \*yy_flex_realloc/inline void *yy_flex_realloc/' | \
-          $(SED) 's/#define YY_BUF_SIZE 16384/#define YY_BUF_SIZE (16384*64)/' > $@
+          $(SED) 's/#define YY_BUF_SIZE 16384/#define YY_BUF_SIZE (16384*64)/' \
+              > $@.tmp
+	$(VERB) diff -q $@ $@.tmp || ${MV} -f $@.tmp $@
+	@# remove the output of flex if it didn't get moved over...
+	@rm -f $@.tmp
 
 # Rule for building the bison parsers...
 %.c: %.y     # Cancel built-in rules for yacc
 %.h: %.y     # Cancel built-in rules for yacc
 %.cpp %.h : %.y
 	@echo Bison\'ing $<...
 	$(VERB) $(BISON) -v -d -p $(<:%Parser.y=%) $*.y
-	$(VERB) ${MV} -f $*.tab.c $*.cpp
-	$(VERB) ${MV} -f $*.tab.h $*.h
+	$(VERB) diff -q $*.tab.c $*.cpp || ${MV} -f $*.tab.c $*.cpp
+	$(VERB) diff -q $*.tab.h $*.h || ${MV} -f $*.tab.h $*.h
+	@# If the files were not updated, don't leave them lying around...
+	@rm -f $*.tab.c $*.tab.h
 
 # To create the directories...
 %/.dir: