Build optimizations

Coauthor: Antigravity

Makefile

@@ -2,6 +2,13 @@
 LOG_REDIR = >&
 TIME=/usr/bin/time --format "Elapsed: %E, Memory: %M KB [Swaps %W]"
 
+# Enable ccache for Verilator compilation
+export OBJCACHE = ccache
+export CXX = clang++
+export CC = clang
+export OPT_FAST = -O1
+export OPT_SLOW = -O0
+
 # Makefile variables
 # Use as many threads as possible while keeping 2 for IO, browsing, etc.
 # USE_PROCS = $(( $(shell nproc --all) - 2 ))
@@ -82,7 +89,7 @@ prepare_area:
 	@if [ ! -d $(PROJ_BASE)/logs ]; then mkdir -p $(PROJ_BASE)/logs; fi
 
 #
-# C code generation from SystemVerilog
+# C code generation from SystemVerilog (optional translation/lint)
 #
 build_sv: prepare_area $(SV_OUT)
 
@@ -98,9 +105,9 @@ $(SV_OUT): $(PROJ_BASE)/logs $(SV_DEPS)
 #
 # C code build to generate testbench executable
 #
-build_cpp: build_sv $(CPP_OUT)
+build_cpp: prepare_area $(CPP_OUT)
 
-$(CPP_OUT): $(SV_OUT)
+$(CPP_OUT): $(SV_DEPS)
 	$(info #-------------------------)
 	$(info # Building CPP ($(USE_PROCS) threads))
 	$(info #-------------------------)