Add rule and workflow to compare results of micro-timing tests

- Added rules to .testing/Makefile to invoke build.timing, run.timing for the
  "target" code checked out for regression tests
- Appended to existing GH "perfmon" workflow

.github/workflows/perfmon.yml

@@ -40,14 +40,36 @@ jobs:
         sudo sysctl -w kernel.perf_event_paranoid=2
         make perf DO_REGRESSION_TESTS=true
 
+    # This job assumes that build/target_codebase was cloned above
+    - name: Compile timing tests for reference code
+      if: ${{ github.event_name == 'pull_request' }}
+      run: >-
+        make -j build.timing_target
+        MOM_TARGET_SLUG=$GITHUB_REPOSITORY
+        MOM_TARGET_LOCAL_BRANCH=$GITHUB_BASE_REF
+        DO_REGRESSION_TESTS=true
+
     - name: Compile timing tests
       run: |
         make -j build.timing
 
+    # DO_REGERESSION_TESTS=true is needed here to set the internal macro TARGET_CODEBASE
+    - name: Run timing tests for reference code
+      if: ${{ github.event_name == 'pull_request' }}
+      run: >-
+        make -j run.timing_target
+        DO_REGRESSION_TESTS=true
+
     - name: Run timing tests
       run: |
         make -j run.timing
 
     - name: Display timing results
       run: |
         make -j show.timing
+
+    - name: Display comparison of timing results
+      if: ${{ github.event_name == 'pull_request' }}
+      run: >-
+        make -j compare.timing
+        DO_REGRESSION_TESTS=true

.testing/Makefile

@@ -217,7 +217,6 @@ endif
 
 FMS_SOURCE = $(call SOURCE,deps/fms/src)
 
-
 #---
 # Rules
 
@@ -684,6 +683,24 @@ show.timing: $(foreach f, $(TIMING_EXECS), work/timing/$(f).show)
 $(WORKSPACE)/work/timing/%.show:
 	./tools/disp_timing.py $(@:.show=.out)
 
+# Invoke the above unit/timing rules for a "target" code
+# Invoke with appropriate macros defines, i.e.
+#   make build.timing_target MOM_TARGET_URL=... MOM_TARGET_BRANCH=... TARGET_CODEBASE=build/target_codebase
+#   make run.timing_target TARGET_CODEBASE=build/target_codebase
+
+TIMING_TARGET_EXECS ?= $(basename $(notdir $(wildcard $(TARGET_CODEBASE)/config_src/drivers/timing_tests/*.F90) ) )
+
+.PHONY: build.timing_target
+build.timing_target: $(foreach f, $(TIMING_TARGET_EXECS), $(TARGET_CODEBASE)/.testing/build/timing/$(f))
+.PHONY: run.timing_target
+run.timing_target: $(foreach f, $(TIMING_TARGET_EXECS), $(TARGET_CODEBASE)/.testing/work/timing/$(f).out)
+.PHONY: compare.timing
+compare.timing: $(foreach f, $(filter $(TIMING_EXECS),$(TIMING_TARGET_EXECS)), work/timing/$(f).compare)
+$(WORKSPACE)/work/timing/%.compare: $(TARGET_CODEBASE)
+	./tools/disp_timing.py -r $(TARGET_CODEBASE)/.testing/$(@:.compare=.out) $(@:.compare=.out)
+$(TARGET_CODEBASE)/.testing/%: | $(TARGET_CODEBASE)
+	cd $(TARGET_CODEBASE)/.testing && make $*
+
 # General rule to run a unit test executable
 # Pattern is to run build/unit/executable and direct output to executable.out
 $(WORKSPACE)/work/unit/%.out: build/unit/%