scripts: Support for incremental compilation

The scripts are looking for a previous run result, a routed design
checkpoint to use it as a reference during the incremental build flow.
Before clearing the project files, the scrips will save the reference dcp
file in the project folder.
If the reference dcp does not exists the build continues normally.

Proposed workflow:
  1. Build your project normally with 'make' or place manually a
  reference.dcp file in the Vivado project folder.
  2. Do some minor modifications
  3. Run the make with the following option:
    make MODE=incr
  4. Repeat steps 2-3

.gitignore

@@ -1,5 +1,6 @@
 ipcache
 *.ip_user_files
+*.dcp
 *.cache
 *.data
 *.xpr

projects/scripts/adi_project.tcl

@@ -22,6 +22,8 @@ if {[info exists ::env(ADI_USE_OOC_SYNTHESIS)]} {
   set ADI_USE_OOC_SYNTHESIS 0
 }
 
+set ADI_USE_INCR_COMP 1
+
 set p_board "not-applicable"
 set p_device "none"
 set sys_zynq 1
@@ -37,6 +39,7 @@ proc adi_project_xilinx {project_name {mode 0}} {
   global REQUIRED_VIVADO_VERSION
   global IGNORE_VERSION_CHECK
   global ADI_USE_OOC_SYNTHESIS
+  global ADI_USE_INCR_COMP
 
   if [regexp "_ac701$" $project_name] {
     set p_device "xc7a200tfbg676-2"
@@ -165,6 +168,13 @@ proc adi_project_xilinx {project_name {mode 0}} {
   } else {
     write_hwdef -file "$project_name.data/$project_name.hwdef"
   }
+
+  if {$ADI_USE_INCR_COMP == 1} {
+    if {[file exists ./reference.dcp]} {
+      set_property incremental_checkpoint ./reference.dcp [get_runs impl_1]
+    }
+  }
+
 }
 
 proc adi_project_files {project_name project_files} {

projects/scripts/project-xilinx.mk

@@ -33,13 +33,15 @@ M_DEPS += $(wildcard system_constr.xdc) # Not all projects have this file
 M_DEPS += $(HDL_PROJECT_PATH)scripts/adi_project.tcl
 M_DEPS += $(HDL_PROJECT_PATH)scripts/adi_env.tcl
 M_DEPS += $(HDL_PROJECT_PATH)scripts/adi_board.tcl
+M_DEPS += prepare_incremental_compile
 
 M_DEPS += $(foreach dep,$(LIB_DEPS),$(HDL_LIBRARY_PATH)$(dep)/component.xml)
 
-.PHONY: all lib clean clean-all
+.PHONY: all lib clean clean-all prepare_incremental_compile 
 all: lib $(PROJECT_NAME).sdk/system_top.hdf
 
 clean:
+	-rm -f reference.dcp
 	$(call clean, \
 		$(CLEAN_TARGET), \
 		$(HL)$(PROJECT_NAME)$(NC) project)
@@ -49,6 +51,19 @@ clean-all: clean
 		$(MAKE) -C $(HDL_LIBRARY_PATH)$${lib} clean; \
 	done
 
+MODE ?= "default"
+
+prepare_incremental_compile:
+	@if [ $(MODE) = incr ]; then \
+		if [ -f */impl_1/system_top_routed.dcp ]; then \
+			echo Found previous run result at `ls */impl_1/system_top_routed.dcp`; \
+			cp -u */impl_1/system_top_routed.dcp ./reference.dcp ; \
+		fi; \
+		if [ -f ./reference.dcp ]; then \
+			echo Using reference checkpoint for incremental compilation; \
+		fi; \
+	fi; 
+
 $(PROJECT_NAME).sdk/system_top.hdf: $(M_DEPS)
 	-rm -rf $(CLEAN_TARGET)
 	$(call build, \