synthesis: minimal synthesis to drive MAX_UNGROUP_SIZE policy

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

flow/Makefile

@@ -466,8 +466,9 @@ do-synth-report:
 SYNTH_SCRIPT ?= $(SCRIPTS_DIR)/synth.tcl
 
 $(SYNTH_STOP_MODULE_SCRIPT):
-	mkdir -p $(RESULTS_DIR) $(LOG_DIR) $(REPORTS_DIR)
+	mkdir -p $(OBJECTS_DIR) $(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
+	python $(SCRIPTS_DIR)/synth_keep.py $(OBJECTS_DIR)/synth.json $(SYNTH_STOP_MODULE_SCRIPT) $(or $(MAX_UNGROUP_SIZE),0)
 
 ifeq ($(SYNTH_HIERARCHICAL), 1)
 do-yosys: $(SYNTH_STOP_MODULE_SCRIPT)

flow/scripts/synth.tcl

@@ -1,6 +1,7 @@
 source $::env(SCRIPTS_DIR)/synth_preamble.tcl
 
 if { [info exist ::env(SYNTH_HIERARCHICAL)] && $::env(SYNTH_HIERARCHICAL) == 1 && [file isfile $::env(SYNTH_STOP_MODULE_SCRIPT)] } {
+  hierarchy -check -top $::env(DESIGN_NAME)
   puts "Sourcing $::env(SYNTH_STOP_MODULE_SCRIPT)"
   source $::env(SYNTH_STOP_MODULE_SCRIPT)
 }

flow/scripts/synth_hier_report.tcl

@@ -1,71 +1,19 @@
 source $::env(SCRIPTS_DIR)/synth_preamble.tcl
 
-# Hierarchical synthesis
-synth  -top $::env(DESIGN_NAME)
-if { [info exist ::env(ADDER_MAP_FILE)] && [file isfile $::env(ADDER_MAP_FILE)] } {
-  techmap -map $::env(ADDER_MAP_FILE)
-}
-techmap
-if {[info exist ::env(DFF_LIB_FILE)]} {
-  dfflibmap -liberty $::env(DFF_LIB_FILE)
-} else {
-  dfflibmap -liberty $::env(DONT_USE_SC_LIB)
-}
-puts "abc [join $abc_args " "]"
-abc {*}$abc_args
-
-tee -o $::env(REPORTS_DIR)/synth_hier_stat.txt stat {*}$stat_libs
-
-if { [info exist ::env(REPORTS_DIR)] && [file isfile $::env(REPORTS_DIR)/synth_hier_stat.txt] } {
-  set ungroup_threshold 0
-  if { [info exist ::env(MAX_UNGROUP_SIZE)] && $::env(MAX_UNGROUP_SIZE) > 0 } {
-    set ungroup_threshold $::env(MAX_UNGROUP_SIZE)
-    puts "Ungroup modules of size $ungroup_threshold"
-  }
-  hierarchy -check -top $::env(DESIGN_NAME)
-  set fptr [open $::env(REPORTS_DIR)/synth_hier_stat.txt r]
-  set contents [read -nonewline $fptr]
-  close $fptr
-  set split_cont [split $contents "\n"]
-  set hierarchy_section 0
-  set module_list {}
-  foreach line $split_cont {
-    if {[regexp {=== design hierarchy ===} $line]} {
-      set hierarchy_section 1
-      continue
-    }
-    if {[regexp {   Number of wires.*} $line ]} {
-      set hierarchy_section 0
-      continue
-    }
-    if { $hierarchy_section == 1 } {
-      if {[regexp { +(\S+) +.*} $line -> module_name]} {
-        lappend module_list $module_name
-        puts "Found module $module_name"
-      }
-    }
-  }
-  set out_script_ptr [open $::env(OBJECTS_DIR)/mark_hier_stop_modules.tcl w]
-  puts $out_script_ptr "hierarchy -check -top $::env(DESIGN_NAME)"
-  foreach module $module_list {
-    tee -o $::env(REPORTS_DIR)/synth_hier_stat_temp_module.txt stat -top "$module" {*}$stat_libs
-    set fptr1 [open $::env(REPORTS_DIR)/synth_hier_stat_temp_module.txt r]
-    set contents1 [read -nonewline $fptr1]
-    close $fptr1
-    set split_cont1 [split $contents1 "\n"]
-    foreach line $split_cont1 {
-      if {[regexp { +Chip area for top module '(\S+)': (.*)} $line -> module_name area]} {
-        puts "Area of module $module_name is $area"
-        if {[expr $area > $ungroup_threshold]} {
-           puts "Preserving hierarchical module: $module_name"
-           puts $out_script_ptr "select -module {$module_name}"
-           puts $out_script_ptr "setattr -mod -set keep_hierarchy 1"
-           puts $out_script_ptr "select -clear"
-        }
-      }
-    }
-    file delete -force $::env(REPORTS_DIR)/synth_hier_stat_temp_module.txt
-  }
-  close $out_script_ptr
+set ungroup_threshold 0
+if { [info exist ::env(MAX_UNGROUP_SIZE)] && $::env(MAX_UNGROUP_SIZE) > 0 } {
+  set ungroup_threshold $::env(MAX_UNGROUP_SIZE)
+  puts "Ungroup modules of size $ungroup_threshold"
 }
 
+# Minimal hierarchical synthesis to use number of cells to drive policy
+# of whether to flatten a module or not.
+synth -run :coarse -top $::env(DESIGN_NAME)
+# These commands are cherry-picked from the "synth -run coarse:" list
+# of commands in the Yosys manual.
+#
+# 'proc' pass is called 'procs' to avoid conflict with tcl 'proc' command
+procs
+memory -nomap
+memory_map
+json -o $::env(OBJECTS_DIR)/synth.json

flow/scripts/synth_keep.py

@@ -0,0 +1,20 @@
+import json
+import sys
+
+
+def main(args):
+    threshold = int(args[2])
+    with open(args[0], "r") as f:
+        synth = json.load(f)
+
+    print("Preserving hierarchical modules...")
+    with open(args[1], "w") as f:
+        for name, module in synth["modules"].items():
+            if len(module["cells"]) > threshold:
+                f.write("select -module {\\" + name + "}\n")
+                f.write("setattr -mod -set keep_hierarchy 1\n")
+                f.write("select -clear\n")
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])