Fix hash collisions in CompilationResultBuilder.buildLabelOffsets().

LIRInstruction#hashCode() was inadequate for use in (identity) hash maps, since it was based on #id() which for many instructions would be -1 or -2, causing excessive hash collisions.
Removing the hashCode() override so that the identity hash code is returned instead.

Author: woess

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/lir/LIRInstruction.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2009, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -473,11 +473,6 @@ public LIRInstructionClass<?> getLIRInstructionClass() {
         return instructionClass;
     }
 
-    @Override
-    public int hashCode() {
-        return id;
-    }
-
     public boolean needsClearUpperVectorRegisters() {
         return false;
     }