From 706960a1390d3e9a25869f7300a11f1699489076 Mon Sep 17 00:00:00 2001
From: caheckman <48068198+caheckman@users.noreply.github.com>
Date: Thu, 9 May 2019 11:32:26 -0400
Subject: [PATCH] removing implied casts in array index expressions

---
 .../Decompiler/src/decompile/cpp/printc.cc    | 41 +++++++++++++++++--
 .../Decompiler/src/decompile/cpp/printc.hh    |  3 +-
 2 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/Ghidra/Features/Decompiler/src/decompile/cpp/printc.cc b/Ghidra/Features/Decompiler/src/decompile/cpp/printc.cc
index 7c3fa0f073..218a794a8f 100644
--- a/Ghidra/Features/Decompiler/src/decompile/cpp/printc.cc
+++ b/Ghidra/Features/Decompiler/src/decompile/cpp/printc.cc
@@ -577,8 +577,12 @@ void PrintC::opReturn(const PcodeOp *op)
 void PrintC::opIntZext(const PcodeOp *op)
 
 {
-  if (castStrategy->isZextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType()))
-    opTypeCast(op);
+  if (castStrategy->isZextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType())) {
+    if (isExtensionCastImplied(op))
+      pushVnImplied(op->getIn(0),op,mods);
+    else
+      opTypeCast(op);
+  }
   else
     opFunc(op);
 }
@@ -586,8 +590,12 @@ void PrintC::opIntZext(const PcodeOp *op)
 void PrintC::opIntSext(const PcodeOp *op)
 
 {
-  if (castStrategy->isSextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType()))
-    opTypeCast(op);
+  if (castStrategy->isSextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType())) {
+    if (isExtensionCastImplied(op))
+      pushVnImplied(op->getIn(0),op,mods);
+    else
+      opTypeCast(op);
+  }
   else
     opFunc(op);
 }
@@ -1247,6 +1255,31 @@ bool PrintC::printCharacterConstant(ostream &s,const Address &addr,int4 charsize
   return res;
 }
 
+/// \brief Is the given ZEXT/SEXT cast implied by the expression its in
+///
+/// We know that the given ZEXT or SEXT op can be viewed as a natural \e cast operation.
+/// Sometimes such a cast is implied by the expression its in, and the cast itself
+/// doesn't need to be printed.
+/// \param op is the given ZEXT or SEXT PcodeOp
+/// \return \b true if the op as a cast does not need to be printed
+bool PrintC::isExtensionCastImplied(const PcodeOp *op) const
+
+{
+  const Varnode *outVn = op->getOut();
+  if (outVn->isExplicit()) {
+
+  }
+  else {
+    PcodeOp *expOp = outVn->loneDescend();
+    if (expOp != (PcodeOp *)0) {
+      OpCode opc = expOp->code();
+      if (opc == CPUI_PTRADD)
+	return true;
+    }
+  }
+  return false;
+}
+
 /// \brief Push a single character constant to the RPN stack
 ///
 /// For C, a character constant is usually emitted as the character in single quotes.
diff --git a/Ghidra/Features/Decompiler/src/decompile/cpp/printc.hh b/Ghidra/Features/Decompiler/src/decompile/cpp/printc.hh
index d65e9be483..c27e9ff495 100644
--- a/Ghidra/Features/Decompiler/src/decompile/cpp/printc.hh
+++ b/Ghidra/Features/Decompiler/src/decompile/cpp/printc.hh
@@ -153,9 +153,10 @@ protected:
   void emitCommentGroup(const PcodeOp *inst);		///< Emit comments associated with a given statement
   void emitCommentFuncHeader(const Funcdata *fd);	///< Emit comments in the given function's header
   void opFunc(const PcodeOp *op);			///< Push a \e functional expression based on the given p-code op to the RPN stack
-  void opTypeCast(const PcodeOp *op);			///< Pus the given p-code op using type-cast syntax to the RPN stack
+  void opTypeCast(const PcodeOp *op);			///< Push the given p-code op using type-cast syntax to the RPN stack
   static bool hasCharTerminator(uint1 *buffer,int4 size,int4 charsize);
   bool printCharacterConstant(ostream &s,const Address &addr,int4 charsize) const;
+  bool isExtensionCastImplied(const PcodeOp *op) const;
   virtual void pushConstant(uintb val,const Datatype *ct,
 			    const Varnode *vn,const PcodeOp *op);
   virtual bool pushEquate(uintb val,int4 sz,const EquateSymbol *sym,