GP-3378 Remove op when clearing placeholder

Ghidra/Features/Decompiler/src/decompile/cpp/coreaction.cc

@@ -1466,14 +1466,8 @@ void ActionFuncLink::funcLinkInput(FuncCallSpecs *fc,Funcdata &data)
 	data.opInsertInput(op,data.newVarnode(param->getSize(),param->getAddress()),op->numInput());
     }
   }
-  if (spacebase != (AddrSpace *)0) {	// If we need it, create the stackplaceholder
+  if (spacebase != (AddrSpace *)0)	// If we need it, create the stackplaceholder
-    PcodeOp *op = fc->getOp();
+    fc->createPlaceholder(data, spacebase);
-    int4 slot = op->numInput();
-    Varnode *loadval = data.opStackLoad(spacebase,0,1,op,(Varnode *)0,false);
-    data.opInsertInput(op,loadval,slot);
-    fc->setStackPlaceholderSlot(slot);
-    loadval->setSpacebasePlaceholder();
-  }
 }
 
 /// \brief Set up the return value recovery process for a single sub-function call

Ghidra/Features/Decompiler/src/decompile/cpp/fspec.cc

@@ -4554,6 +4554,23 @@ void FuncProto::decode(Decoder &decoder,Architecture *glb)
   updateThisPointer();
 }
 
+/// \brief Add a an input parameter that will resolve to the current stack offset for \b this call site
+///
+/// A LOAD from a free reference to the \e spacebase pointer of the given AddrSpace is created and
+/// its output is added as a parameter to the call.  Later the LOAD should resolve to a COPY from
+/// a Varnode in the AddrSpace, whose offset is then the current offset.
+/// \param data is the function where the LOAD is created
+/// \param spacebase is the given (stack) AddrSpace
+void FuncCallSpecs::createPlaceholder(Funcdata &data,AddrSpace *spacebase)
+
+{
+  int4 slot = op->numInput();
+  Varnode *loadval = data.opStackLoad(spacebase,0,1,op,(Varnode *)0,false);
+  data.opInsertInput(op,loadval,slot);
+  setStackPlaceholderSlot(slot);
+  loadval->setSpacebasePlaceholder();
+}
+
 /// \brief Calculate the stack offset of \b this call site
 ///
 /// The given Varnode must be the input to the CALL in the \e placeholder slot
@@ -4577,8 +4594,7 @@ void FuncCallSpecs::resolveSpacebaseRelative(Funcdata &data,Varnode *phvn)
 
   if (stackPlaceholderSlot >= 0) {
     if (op->getIn(stackPlaceholderSlot) == phvn) {
-      data.opRemoveInput(op,stackPlaceholderSlot);
+      abortSpacebaseRelative(data);
-      clearStackPlaceholderSlot();
       return;
     }
   }
@@ -4610,8 +4626,12 @@ void FuncCallSpecs::abortSpacebaseRelative(Funcdata &data)
 
 {
   if (stackPlaceholderSlot >= 0) {
+    Varnode *vn = op->getIn(stackPlaceholderSlot);
     data.opRemoveInput(op,stackPlaceholderSlot);
     clearStackPlaceholderSlot();
+    // Remove the op producing the placeholder as well
+    if (vn->hasNoDescend() && vn->getSpace()->getType() == IPTR_INTERNAL && vn->isWritten())
+      data.opDestroy(vn->getDef());
   }
 }
 

Ghidra/Features/Decompiler/src/decompile/cpp/fspec.hh

@@ -1610,6 +1610,10 @@ class FuncCallSpecs : public FuncProto {
   void commitNewInputs(Funcdata &data,vector<Varnode *> &newinput);
   void commitNewOutputs(Funcdata &data,Varnode *newout);
   void collectOutputTrialVarnodes(vector<Varnode *> &trialvn);
+  void setStackPlaceholderSlot(int4 slot) { stackPlaceholderSlot = slot;
+      if (isinputactive) activeinput.setPlaceholderSlot(); }	///< Set the slot of the stack-pointer placeholder
+  void clearStackPlaceholderSlot(void) {
+    stackPlaceholderSlot = -1; if (isinputactive) activeinput.freePlaceholderSlot(); }	///< Release the stack-pointer placeholder
 public:
   enum {
     offset_unknown = 0xBADBEEF					///< "Magic" stack offset indicating the offset is unknown
@@ -1629,10 +1633,6 @@ public:
   int4 getParamshift(void) const { return paramshift; }		///< Get the parameter shift for this call site
   int4 getMatchCallCount(void) const { return matchCallCount; }	///< Get the number of calls the caller makes to \b this sub-function
   int4 getStackPlaceholderSlot(void) const { return stackPlaceholderSlot; }	///< Get the slot of the stack-pointer placeholder
-  void setStackPlaceholderSlot(int4 slot) { stackPlaceholderSlot = slot;
-      if (isinputactive) activeinput.setPlaceholderSlot(); }	///< Set the slot of the stack-pointer placeholder
-  void clearStackPlaceholderSlot(void) {
-    stackPlaceholderSlot = -1; if (isinputactive) activeinput.freePlaceholderSlot(); }	///< Release the stack-pointer placeholder
 
   void initActiveInput(void);			 ///< Turn on analysis recovering input parameters
   void clearActiveInput(void) { isinputactive = false; }	///< Turn off analysis recovering input parameters
@@ -1651,6 +1651,7 @@ public:
   void deindirect(Funcdata &data,Funcdata *newfd);
   void forceSet(Funcdata &data,const FuncProto &fp);
   void insertPcode(Funcdata &data);
+  void createPlaceholder(Funcdata &data,AddrSpace *spacebase);
   void resolveSpacebaseRelative(Funcdata &data,Varnode *phvn);
   void abortSpacebaseRelative(Funcdata &data);
   void finalInputCheck(void);