synth: add canonicalization step before synthesis

This saves hours on larger designs when unecessary macro rebuilds
are avoided and makes the build scripts less brittle.

this will clean out unused modules and produce the a canonical
$(RESULTS_DIR)/1_synth.json file.

This file will not change hash when unrelated changes to the design changes,
such as when non-synthesis(simulation) files are mixed into VERILOG_FILES.

This is particularly useful when doing synthesis on macros out of a folder of
Verilog files and you don't want to carefully groom the list of VERILOG_FILES.

This also allows bazel-orfs to handle actual dependencies for a folder
of .v/.sv files in much the same fashion that CMake can figure out
dependencies given a list of .cpp and header files.

Signed-off-by: Øyvind Harboe <[email protected]>

Author: oharboe

flow/Makefile

@@ -483,7 +483,8 @@ export SYNTH_MEMORY_MAX_BITS ?= 4096
 
 $(SYNTH_STOP_MODULE_SCRIPT):
 	mkdir -p $(RESULTS_DIR) $(LOG_DIR) $(REPORTS_DIR)
-	($(TIME_CMD) $(YOSYS_CMD) $(YOSYS_FLAGS) -c $(HIER_REPORT_SCRIPT)) 2>&1 | tee $(LOG_DIR)/1_1_yosys_hier_report.log
+	(export VERILOG_FILES=$(RESULTS_DIR)/1_synth.json; \
+	$(TIME_CMD) $(YOSYS_CMD) $(YOSYS_FLAGS) -c $(HIER_REPORT_SCRIPT)) 2>&1 | tee $(LOG_DIR)/1_1_yosys_hier_report.log
 
 ifeq ($(SYNTH_HIERARCHICAL), 1)
 do-yosys: $(SYNTH_STOP_MODULE_SCRIPT)
@@ -499,11 +500,20 @@ $(SDC_FILE_CLOCK_PERIOD): $(SDC_FILE)
 yosys-dependencies: $(DONT_USE_LIBS) $(WRAPPED_LIBS) $(DONT_USE_SC_LIB) $(DFF_LIB_FILE) $(VERILOG_FILES) $(CACHED_NETLIST) $(LATCH_MAP_FILE) $(ADDER_MAP_FILE)
 
 .PHONY: do-yosys
-do-yosys: yosys-dependencies
+do-yosys:
 	mkdir -p $(RESULTS_DIR) $(LOG_DIR) $(REPORTS_DIR) $(OBJECTS_DIR)
-	($(TIME_CMD) $(YOSYS_CMD) $(YOSYS_FLAGS) -c $(SYNTH_SCRIPT)) 2>&1 | tee $(LOG_DIR)/1_1_yosys.log
+	(export VERILOG_FILES=$(RESULTS_DIR)/1_synth.json; \
+	$(TIME_CMD) $(YOSYS_CMD) $(YOSYS_FLAGS) -c $(SYNTH_SCRIPT)) 2>&1 | tee -a $(LOG_DIR)/1_1_yosys.log
 
-$(RESULTS_DIR)/1_1_yosys.v: $(SDC_FILE_CLOCK_PERIOD)
+.PHONY: do-yosys-canonicalize
+do-yosys-canonicalize: yosys-dependencies
+	mkdir -p $(RESULTS_DIR) $(LOG_DIR) $(REPORTS_DIR) $(OBJECTS_DIR)
+	($(TIME_CMD) $(YOSYS_CMD) $(YOSYS_FLAGS) -c $(SCRIPTS_DIR)/synth_canonicalize.tcl) 2>&1 | tee $(LOG_DIR)/1_1_yosys.log
+
+$(RESULTS_DIR)/1_synth.json: $(RESULTS_DIR)/1_1_yosys.v $(SDC_FILE_CLOCK_PERIOD)
+	$(UNSET_AND_MAKE) do-yosys-canonicalize
+
+$(RESULTS_DIR)/1_1_yosys.v: $(RESULTS_DIR)/1_synth.json $(SDC_FILE_CLOCK_PERIOD)
 	$(UNSET_AND_MAKE) do-yosys
 
 $(RESULTS_DIR)/1_synth.sdc: $(SDC_FILE)
@@ -520,7 +530,7 @@ $(RESULTS_DIR)/1_synth.v: $(RESULTS_DIR)/1_1_yosys.v
 
 .PHONY: clean_synth
 clean_synth:
-	rm -f $(RESULTS_DIR)/1_*.v $(RESULTS_DIR)/1_synth.sdc $(RESULTS_DIR)/mem.json
+	rm -f $(RESULTS_DIR)/1_* $(RESULTS_DIR)/mem.json
 	rm -f $(REPORTS_DIR)/synth_*
 	rm -f $(LOG_DIR)/1_*
 	rm -f $(SYNTH_STOP_MODULE_SCRIPT)

flow/scripts/synth_canonicalize.tcl

@@ -0,0 +1,7 @@
+source $::env(SCRIPTS_DIR)/synth_preamble.tcl
+hierarchy -check -top $::env(DESIGN_NAME)
+procs
+# Get rid of unused modules
+clean
+# The hash of this file will not change if files not part of synthesis do not change
+json -o $::env(RESULTS_DIR)/1_synth.json

flow/scripts/synth_preamble.tcl

@@ -106,8 +106,6 @@ close $constr
 proc synthesize_check {synth_args} {
   # Generic synthesis
   log_cmd synth -top $::env(DESIGN_NAME) -run :fine {*}$synth_args
-  # Get rid of unused modules
-  clean
   json -o $::env(RESULTS_DIR)/mem.json
   # Run report and check here so as to fail early if this synthesis run is doomed
   exec -- python3 $::env(SCRIPTS_DIR)/mem_dump.py --max-bits $::env(SYNTH_MEMORY_MAX_BITS) $::env(RESULTS_DIR)/mem.json