From 36a1a33b25114d3f9f2dd6520209ed6dcfc37bb6 Mon Sep 17 00:00:00 2001
From: caheckman <48068198+caheckman@users.noreply.github.com>
Date: Tue, 31 May 2022 14:10:55 -0400
Subject: [PATCH] GP-2079 Add explicit compare method for TypePointerRel

---
 .../Decompiler/src/decompile/cpp/type.cc      | 20 +++++++++++++++++++
 .../Decompiler/src/decompile/cpp/type.hh      |  1 +
 2 files changed, 21 insertions(+)

diff --git a/Ghidra/Features/Decompiler/src/decompile/cpp/type.cc b/Ghidra/Features/Decompiler/src/decompile/cpp/type.cc
index 97134636cb..e4ad058a1f 100644
--- a/Ghidra/Features/Decompiler/src/decompile/cpp/type.cc
+++ b/Ghidra/Features/Decompiler/src/decompile/cpp/type.cc
@@ -1870,6 +1870,26 @@ void TypePointerRel::printRaw(ostream &s) const
   s << ']';
 }
 
+int4 TypePointerRel::compare(const Datatype &op,int4 level) const
+
+{
+  int4 res = TypePointer::compare(op,level);	// Compare as plain pointers first
+  if (res != 0) return res;
+  // Both must be relative pointers
+  TypePointerRel *tp = (TypePointerRel *) &op;
+  // Its possible a formal relative pointer gets compared to its equivalent ephemeral version.
+  // In which case, we prefer the formal version.
+  if (stripped == (TypePointer *)0) {
+    if (tp->stripped != (TypePointer *)0)
+      return -1;
+  }
+  else {
+    if (tp->stripped == (TypePointer *)0)
+      return 1;
+  }
+  return 0;
+}
+
 int4 TypePointerRel::compareDependency(const Datatype &op) const
 
 {
diff --git a/Ghidra/Features/Decompiler/src/decompile/cpp/type.hh b/Ghidra/Features/Decompiler/src/decompile/cpp/type.hh
index bd4fc6a7e3..41ea5a1937 100644
--- a/Ghidra/Features/Decompiler/src/decompile/cpp/type.hh
+++ b/Ghidra/Features/Decompiler/src/decompile/cpp/type.hh
@@ -461,6 +461,7 @@ public:
   /// \return the offset value in \e address \e units
   int4 getPointerOffset(void) const { return AddrSpace::byteToAddressInt(offset, wordsize); }
   virtual void printRaw(ostream &s) const;
+  virtual int4 compare(const Datatype &op,int4 level) const;
   virtual int4 compareDependency(const Datatype &op) const;
   virtual Datatype *clone(void) const { return new TypePointerRel(*this); }
   virtual void saveXml(ostream &s) const;