From 348db87f358dc6dc822e6bfa163e17b986fd5d42 Mon Sep 17 00:00:00 2001
From: Foivos Zakkak <fzakkak@redhat.com>
Date: Mon, 13 Dec 2021 16:23:40 +0200
Subject: [PATCH] Refactor: Don't generate 0-sized arrays for methods with no
 arguments

---
 .../objectfile/debugentry/ClassEntry.java      | 18 +++++++++++-------
 .../objectfile/debugentry/MethodEntry.java     |  4 ++--
 .../oracle/objectfile/debugentry/Range.java    | 13 ++++++++-----
 .../elf/dwarf/DwarfInfoSectionImpl.java        |  3 +++
 4 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/ClassEntry.java b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/ClassEntry.java
index 643ad61ec936..fc21a324bf03 100644
--- a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/ClassEntry.java
+++ b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/ClassEntry.java
@@ -292,14 +292,18 @@ protected MethodEntry processMethod(DebugMethodInfo debugMethodInfo, DebugInfoBa
         debugContext.log("typename %s adding %s method %s %s(%s)\n",
                         typeName, memberModifiers(modifiers), resultTypeName, methodName, formatParams(paramTypes, paramNames));
         TypeEntry resultType = debugInfoBase.lookupTypeEntry(resultTypeName);
-        TypeEntry[] paramTypeArray = new TypeEntry[paramCount];
-        String[] paramNameArray = new String[paramCount];
-        int idx = 0;
-        for (String paramTypeName : paramTypes) {
-            TypeEntry paramType = debugInfoBase.lookupTypeEntry(TypeEntry.canonicalize(paramTypeName));
-            paramTypeArray[idx++] = paramType;
+        TypeEntry[] paramTypeArray = null;
+        String[] paramNameArray = null;
+        if (paramCount != 0) {
+            paramTypeArray = new TypeEntry[paramCount];
+            paramNameArray = new String[paramCount];
+            int idx = 0;
+            for (String paramTypeName : paramTypes) {
+                TypeEntry paramType = debugInfoBase.lookupTypeEntry(TypeEntry.canonicalize(paramTypeName));
+                paramTypeArray[idx++] = paramType;
+            }
+            paramNameArray = paramNames.toArray(paramNameArray);
         }
-        paramNameArray = paramNames.toArray(paramNameArray);
         /*
          * n.b. the method file may differ from the owning class file when the method is a
          * substitution
diff --git a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/MethodEntry.java b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/MethodEntry.java
index a5ab87a66717..3f1172b612d0 100644
--- a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/MethodEntry.java
+++ b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/MethodEntry.java
@@ -31,8 +31,8 @@
 import com.oracle.objectfile.debuginfo.DebugInfoProvider.DebugMethodInfo;
 
 public class MethodEntry extends MemberEntry {
-    final TypeEntry[] paramTypes;
-    final String[] paramNames;
+    private final TypeEntry[] paramTypes;
+    private final String[] paramNames;
     static final int DEOPT = 1 << 0;
     static final int IN_RANGE = 1 << 1;
     static final int INLINED = 1 << 2;
diff --git a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/Range.java b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/Range.java
index c3f7e5ca594e..71d3674ae61c 100644
--- a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/Range.java
+++ b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/debugentry/Range.java
@@ -182,11 +182,14 @@ private String getExtendedMethodName(boolean includeClass, boolean includeParams
         builder.append(getMethodName());
         if (includeParams) {
             builder.append("(");
-            String prefix = "";
-            for (TypeEntry t : methodEntry.paramTypes) {
-                builder.append(prefix);
-                builder.append(t.getTypeName());
-                prefix = ", ";
+            TypeEntry[] paramTypes = methodEntry.getParamTypes();
+            if (paramTypes != null) {
+                String prefix = "";
+                for (TypeEntry t : paramTypes) {
+                    builder.append(prefix);
+                    builder.append(t.getTypeName());
+                    prefix = ", ";
+                }
             }
             builder.append(')');
         }
diff --git a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/elf/dwarf/DwarfInfoSectionImpl.java b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/elf/dwarf/DwarfInfoSectionImpl.java
index 9a93f68fd374..b8341cf197de 100644
--- a/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/elf/dwarf/DwarfInfoSectionImpl.java
+++ b/substratevm/src/com.oracle.objectfile/src/com/oracle/objectfile/elf/dwarf/DwarfInfoSectionImpl.java
@@ -737,6 +737,9 @@ private int writeMethodParameterDeclarations(DebugContext context, ClassEntry cl
         if (!Modifier.isStatic(method.getModifiers())) {
             pos = writeMethodParameterDeclaration(context, "this", classEntry.getTypeName(), true, isSpecification, buffer, pos);
         }
+        if (method.getParamTypes() == null) {
+            return pos;
+        }
         for (TypeEntry paramType : method.getParamTypes()) {
             String paramTypeName = paramType.getTypeName();
             String paramName = uniqueDebugString("");