Made directory prerequisites order-only prerequisites.

Avoids excessive rebuilding. See
  http://www.kolpackov.net/pipermail/notes/2004-January/000001.html
  http://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html
  http://savannah.gnu.org/support/?104349
for details

diff --git a/src/sawsim.nw b/src/sawsim.nw
index 7b9c1f2f1b9c2c0dc71ecd3c8d5f13bd22be381e..c43a9b30c3ab7c88e26914235ca1cfdefad9b717 100644 (file)
--- a/src/sawsim.nw
+++ b/src/sawsim.nw
@@ -3125,13 +3125,20 @@ TENSION_MODEL_MODS = tension_model parse list tension_balance
 TENSION_MODEL_SRC = $(BUILD_DIR)/tension_model_utils.c $(BUILD_DIR)/global.h \
        $(TENSION_MODEL_MODS:%=$(BUILD_DIR)/%.c) \
        $(TENSION_MODEL_MODS:%=$(BUILD_DIR)/%.h)
-$(BUILD_DIR)/tension_model_utils.c : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(BUILD_DIR)/tension_model_utils.c : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        notangle -Rtension-model-utils.c $< > $@
-$(BIN_DIR)/tension_model_utils : $(TENSION_MODEL_SRC) $(BIN_DIR)
+$(BIN_DIR)/tension_model_utils : $(TENSION_MODEL_SRC) | $(BIN_DIR)
        gcc -g -o $@ $< $(TENSION_MODEL_MODS:%=$(BUILD_DIR)/%.c) $(LIBS:%=-l%)
 clean_tension_model_utils :
        rm -f $(BUILD_DIR)/tension_model_utils.c $(BIN_DIR)/tension_model_utils
-@ 
+@ The pipe symbol [[|]] marks the prerequisits following it (in this
+case, the directories) as ‘order-only’ prerequisites.  The timestamp
+on these prerequisits does not effect whether the rules are executed.
+This is appropriate for directories, where we don't need to recompile
+after an unrelated has been added to the directory, but only when the
+source prerequisites change.  See the [[make]] documentation for more
+details
+(\url{http://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html}).
 
 \subsection{Null}
 \label{sec.null_tension}
@@ -3866,9 +3873,9 @@ check_k_model_MODS = parse string_eval
 K_MODEL_MODS = k_model parse string_eval
 K_MODEL_SRC = $(BUILD_DIR)/k_model_utils.c $(BUILD_DIR)/global.h \
        $(K_MODEL_MODS:%=$(BUILD_DIR)/%.c) $(K_MODEL_MODS:%=$(BUILD_DIR)/%.h)
-$(BUILD_DIR)/k_model_utils.c : $(SRC_DIR)/sawsim.nw $(BUILD)
+$(BUILD_DIR)/k_model_utils.c : $(SRC_DIR)/sawsim.nw | $(BUILD)
        notangle -Rk-model-utils.c $< > $@
-$(BIN_DIR)/k_model_utils : $(K_MODEL_SRC) $(BIN_DIR)
+$(BIN_DIR)/k_model_utils : $(K_MODEL_SRC) | $(BIN_DIR)
        gcc -g -o $@ $< $(K_MODEL_MODS:%=$(BUILD_DIR)/%.c) $(LIBS:%=-l%)
 clean_k_model_utils :
        rm -f $(BUILD_DIR)/k_model_utils.c $(BIN_DIR)/k_model_utils
@@ -5064,15 +5071,15 @@ void get_options(int argc, char **argv, environment_t *env,
 The comment blocks in this [[noweb]] file are in \LaTeX\ with \BibTeX\ citations.
 The comment blocks are extracted (with nicely formatted code blocks), using
 <<latex makefile lines>>=
-$(BUILD_DIR)/sawsim.tex : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(BUILD_DIR)/sawsim.tex : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        noweave -latex -index -delay $< > $@
-$(BUILD_DIR)/sawsim.bib : $(SRC_DIR)/sawsim.bib $(BUILD_DIR)
+$(BUILD_DIR)/sawsim.bib : $(SRC_DIR)/sawsim.bib | $(BUILD_DIR)
        cp -f $< $@
 @ 
 and compiled using
 <<latex makefile lines>>=
 $(DOC_DIR)/sawsim.pdf : $(BUILD_DIR)/sawsim.tex $(BUILD_DIR)/sawsim.bib \
-               $(DOC_DIR)
+               | $(DOC_DIR)
        $(SHELL) -e -c "cd $(BUILD_DIR) && pdflatex sawsim"
        $(SHELL) -e -c "cd $(BUILD_DIR) && bibtex sawsim"
        $(SHELL) -e -c "cd $(BUILD_DIR) && pdflatex sawsim"
@@ -5151,7 +5158,7 @@ all : ./Makefile $(BINS:%=$(BIN_DIR)/%) $(DOCS:%=$(DOC_DIR)/%) ;
 
 view : $(DOC_DIR)/sawsim.pdf
        xpdf $< &
-profile : $(BIN_DIR)/sawsim_profile $(BIN_DIR)
+profile : $(BIN_DIR)/sawsim_profile | $(BIN_DIR)
        $(BIN_DIR)/sawsim_profile -v1e-6 -Mhooke -A.05 -U1 -kkramers_integ \
                -mnull -Mwlc -A0.39e-9,28e-9 -F8
        gprof $(BIN_DIR)/sawsim_profile gmon.out > $@
@@ -5168,11 +5175,11 @@ clean : $(CHECK_BINS:%=clean_%) $(SAWSIM_MODS:%=clean_%) \
        $(SHELL) -e -c "rmdir $(BUILD_DIR) $(BIN_DIR) $(DOC_DIR)"
 
 # Various builds of sawsim
-$(BIN_DIR)/sawsim : $(SAWSIM_SRC) $(BIN_DIR)
+$(BIN_DIR)/sawsim : $(SAWSIM_SRC) | $(BIN_DIR)
        gcc -g -o $@ $< $(SAWSIM_MODS:%=$(BUILD_DIR)/%.c) $(LIBS:%=-l%)
-$(BIN_DIR)/sawsim_static : $(SAWSIM_SRC) $(BIN_DIR)
+$(BIN_DIR)/sawsim_static : $(SAWSIM_SRC) | $(BIN_DIR)
        gcc -g -static -o $@ $< $(SAWSIM_MODS:%=$(BUILD_DIR)/%.c) $(LIBS:%=-l%)
-$(BIN_DIR)/sawsim_profile : $(SAWSIM_SRC) $(BIN_DIR)
+$(BIN_DIR)/sawsim_profile : $(SAWSIM_SRC) | $(BIN_DIR)
        gcc -g -pg -o $@ $< $(SAWSIM_MODS:%=$(BUILD_DIR)/%.c) $(LIBS:%=-l%)
 
 # Create the directories
@@ -5184,25 +5191,25 @@ $(BUILD_DIR) $(BIN_DIR) $(DOC_DIR) :
 # and then $(BUILD_DIR) doesn't match in $$(subst $(BUILD_DIR), ...) 
 .SECONDEXPANSION:
 $(FREE_SAWSIM_MODS:%=$(BUILD_DIR)/%.h) : $$(subst $(BUILD_DIR),$(SRC_DIR),$$@)\
-               $(BUILD_DIR)
+               | $(BUILD_DIR)
        cp -f $< $@
 .SECONDEXPANSION:
 $(FREE_SAWSIM_MODS:%=$(BUILD_DIR)/%.c) : $$(subst $(BUILD_DIR),$(SRC_DIR),$$@)\
-               $(BUILD_DIR)
+               | $(BUILD_DIR)
        cp -f $< $@
 
 ## Basic source generated with noweb
 # The central files sawsim.c and global.h...
-$(BUILD_DIR)/sawsim.c : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(BUILD_DIR)/sawsim.c : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        notangle $< > $@
-$(BUILD_DIR)/global.h : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(BUILD_DIR)/global.h : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        notangle -Rglobal.h $< > $@
 # ... and the modules
-$(NW_SAWSIM_MODS:%=$(BUILD_DIR)/%.h) : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(NW_SAWSIM_MODS:%=$(BUILD_DIR)/%.h) : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        notangle -R$(subst _,-,$(@:$(BUILD_DIR)/%=%)) $< > $@
-$(NW_SAWSIM_MODS:%=$(BUILD_DIR)/%.c) : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(NW_SAWSIM_MODS:%=$(BUILD_DIR)/%.c) : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        notangle -R$(subst _,-,$(@:$(BUILD_DIR)/%=%)) $< > $@
-$(CHECK_BINS:%=$(BUILD_DIR)/%.c) : $(SRC_DIR)/sawsim.nw $(BUILD_DIR)
+$(CHECK_BINS:%=$(BUILD_DIR)/%.c) : $(SRC_DIR)/sawsim.nw | $(BUILD_DIR)
        notangle -R$(subst _,-,$(@:$(BUILD_DIR)/%=%)) $< > $@
 # Note: I use `_' as a space in my file names, but noweb doesn't like
 # that so we use `-' to name the noweb roots and substitute here.
@@ -5213,7 +5220,7 @@ $(BUILD_DIR)/check_sawsim.c : $(SRC_DIR)/sawsim.nw
        notangle -Rchecks $< > $@
 $(BIN_DIR)/check_sawsim : $(BUILD_DIR)/check_sawsim.c $(BUILD_DIR)/global.h \
                $(SAWSIM_MODS:%=$(BUILD_DIR)/%.c) \
-               $(SAWSIM_MODS:%=$(BUILD_DIR)/%.h) $(BIN_DIR)
+               $(SAWSIM_MODS:%=$(BUILD_DIR)/%.h) | $(BIN_DIR)
        gcc -g -o $@ $< $(SAWSIM_MODS:%=$(BUILD_DIR)/%.c) $(CHECK_LIBS:%=-l%)
 clean_check_sawsim :
        rm -f $(BIN_DIR)/check_sawsim $(BUILD_DIR)/check_sawsim.c
@@ -5224,7 +5231,7 @@ $(CHECK_BINS:%=$(BIN_DIR)/%) : $$(subst $(BIN_DIR),$(BUILD_DIR),$$@).c \
                $$(subst $(BIN_DIR)/check_,$(BUILD_DIR)/,$$@).h \
                $$(patsubst %,$(BUILD_DIR)/%.c,$$($$(subst $(BIN_DIR)/,,$$@_MODS)))\
                $$(patsubst %,$(BUILD_DIR)/%.h,$$($$(subst $(BIN_DIR)/,,$$@_MODS)))\
-               $$(BUILD_DIR)/global.h $(BIN_DIR)
+               $$(BUILD_DIR)/global.h | $(BIN_DIR)
        gcc -g -o $@ $< $(@:$(BIN_DIR)/check_%=$(BUILD_DIR)/%.c) \
                $(patsubst %,$(BUILD_DIR)/%.c,$($(subst $(BIN_DIR)/,,$@_MODS)))\
                $(CHECK_LIBS:%=-l%)