Added comments to used flags, clean up code, final fine tuning. (#674)

1 files changed, 14 insertions, 2 deletions

diff --git a/prepare_thomaswue.sh b/prepare_thomaswue.sh
index da0a591..3e75233 100755
--- a/prepare_thomaswue.sh
+++ b/prepare_thomaswue.sh
@@ -20,7 +20,19 @@ sdk use java 21.0.2-graal 1>&2
 
 # ./mvnw clean verify removes target/ and will re-trigger native image creation.
 if [ ! -f target/CalculateAverage_thomaswue_image ]; then
-    NATIVE_IMAGE_OPTS="--gc=epsilon -O3 -H:TuneInlinerExploration=1 -march=native --enable-preview --initialize-at-build-time=dev.morling.onebrc.CalculateAverage_thomaswue\$Scanner"
-    # Use -H:MethodFilter=CalculateAverage_thomaswue.* -H:Dump=:2 -H:PrintGraph=Network for IdealGraphVisualizer graph dumping.
+
+    # Performance tuning flags, optimization level 3, maximum inlining exploration, and compile for the architecture where the native image is generated.
+    NATIVE_IMAGE_OPTS="-O3 -H:TuneInlinerExploration=1 -march=native"
+   
+    # Need to enable preview for accessing the raw address of the foreign memory access API.
+    # Initializing the Scanner to make sure the unsafe access object is known as a non-null compile time constant.
+    NATIVE_IMAGE_OPTS="$NATIVE_IMAGE_OPTS --enable-preview --initialize-at-build-time=dev.morling.onebrc.CalculateAverage_thomaswue\$Scanner"
+
+    # There is no need for garbage collection and therefore also no safepoints required.
+    NATIVE_IMAGE_OPTS="$NATIVE_IMAGE_OPTS --gc=epsilon -H:-GenLoopSafepoints"
+
+    # Uncomment the following line for outputting the compiler graph to the IdealGraphVisualizer
+    # NATIVE_IMAGE_OPTS="$NATIVE_IMAGE_OPTS -H:MethodFilter=CalculateAverage_thomaswue.* -H:Dump=:2 -H:PrintGraph=Network"
+    
     native-image $NATIVE_IMAGE_OPTS -cp target/average-1.0.0-SNAPSHOT.jar -o target/CalculateAverage_thomaswue_image dev.morling.onebrc.CalculateAverage_thomaswue
 fi