Optimize feature loading when require is called with absolute .rb path

If require is called with an absolute path like `/path/to/thing.rb`
we can try that as is first rather than trying `.rb.rb` and `.rb.so` first.

Author: rwstauner

CHANGELOG.md

@@ -16,6 +16,7 @@ Compatibility:
 Performance:
 
 * Optimize calls with `ruby2_keywords` forwarding by deciding it per call site instead of per callee thanks to [my fix in CRuby 3.2](https://bugs.ruby-lang.org/issues/18625) (@eregon).
+* Optimize feature loading when require is called with an absolute path to a .rb file (@rwstauner).
 
 Changes:
 

src/main/java/org/truffleruby/language/loader/FeatureLoader.java

@@ -379,6 +379,16 @@ private String translateIfNativePath(String feature) {
     private String findFeatureWithAndWithoutExtension(String path) {
         assert new File(path).isAbsolute();
 
+        boolean triedWithoutExtension = false;
+
+        if (path.endsWith(TruffleRuby.EXTENSION)) {
+            final String withoutExtension = findFeatureWithExactPath(path);
+            if (withoutExtension != null) {
+                return withoutExtension;
+            }
+            triedWithoutExtension = true;
+        }
+
         if (path.endsWith(".so")) {
             final String pathWithNativeExt = translateIfNativePath(path);
             final String asCExt = findFeatureWithExactPath(pathWithNativeExt);
@@ -397,9 +407,11 @@ private String findFeatureWithAndWithoutExtension(String path) {
             return asCExt;
         }
 
-        final String withoutExtension = findFeatureWithExactPath(path);
-        if (withoutExtension != null) {
-            return withoutExtension;
+        if (!triedWithoutExtension) {
+            final String withoutExtension = findFeatureWithExactPath(path);
+            if (withoutExtension != null) {
+                return withoutExtension;
+            }
         }
 
         return null;