Extend unit tests to check for optimized, native-arch builds.

This is mainly intended to check for correct independence assumptions during
vectorization, but it also doesn't hurt to test all of the code for correct
behavior at more aggressive optimization levels.

Also bumped up the number of cores to speed up compilation on Action runners.

.github/workflows/run-tests.yaml

@@ -15,13 +15,24 @@ jobs:
       matrix:
         config:
         - {
-            name: "Ubuntu Latest GCC, coverage enabled", 
+            name: "Ubuntu Latest GCC (debug, coverage enabled)", 
             os: ubuntu-latest,
-            cov: true
+            type: coverage
           }
         - {
-            name: "macOS Latest Clang", 
-            os: macos-latest
+            name: "Ubuntu Latest GCC (all optimizations)", 
+            os: ubuntu-latest,
+            type: optimized
+          }
+        - {
+            name: "macOS Latest Clang (debug)", 
+            os: macos-latest,
+            type: debug
+          }
+        - {
+            name: "macOS Latest Clang (all optimizations)", 
+            os: macos-latest,
+            type: optimized
           }
 
     steps:
@@ -30,16 +41,20 @@ jobs:
     - name: Get latest CMake
       uses: lukka/get-cmake@latest
 
-    - name: Configure the build for Mac
-      if: ${{ matrix.config.os == 'macos-latest' }}
+    - name: Configure the build (debug)
+      if: ${{ matrix.config.type == 'debug' }}
       run: cmake -S . -B build
 
-    - name: Configure the build with coverage
-      if: ${{ matrix.config.os == 'ubuntu-latest' && matrix.config.cov }}
-      run: cmake -S . -B build -DCODE_COVERAGE=ON 
+    - name: Configure the build (coverage)
+      if: ${{ matrix.config.type == 'coverage' }}
+      run: cmake -S . -B build -DCODE_COVERAGE=ON
+
+    - name: Configure the build (optimized)
+      if: ${{ matrix.config.type == 'optimized' }}
+      run: cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DUSE_MARCH_NATIVE=ON
 
     - name: Run the build
-      run: cmake --build build
+      run: cmake --build build -j 2
 
     - name: Run the tests
       run: |

tests/CMakeLists.txt

@@ -22,6 +22,9 @@ if(CODE_COVERAGE AND CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
     set(DO_CODE_COVERAGE ON)
 endif()
 
+# Test for correct handling of vectorization.
+option(USE_MARCH_NATIVE "Build for native architecture." OFF)
+
 macro(decorate_executable target)
     target_link_libraries(
         ${target}
@@ -38,6 +41,10 @@ macro(decorate_executable target)
         target_link_options(${target} PRIVATE --coverage)
     endif()
 
+    if(USE_MARCH_NATIVE)
+        target_compile_options(${target} PRIVATE -march=native)
+    endif()
+
     gtest_discover_tests(${target})
 endmacro()