From 2ef4843e7076bdd9d1d830ab4be962acefb65235 Mon Sep 17 00:00:00 2001
From: caheckman <48068198+caheckman@users.noreply.github.com>
Date: Fri, 28 Feb 2020 12:13:34 -0500
Subject: [PATCH] more subvariable extension pushes

---
 .../Decompiler/src/decompile/cpp/subflow.cc   | 32 ++++++++++++++-----
 .../Decompiler/src/decompile/cpp/subflow.hh   |  1 +
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.cc b/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.cc
index 9d9f76679c..42d1b44312 100644
--- a/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.cc
+++ b/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.cc
@@ -301,10 +301,7 @@ bool SubvariableFlow::tryCallReturnPush(PcodeOp *op,ReplaceVarnode *rvn)
   if (fc->isOutputLocked()) return false;
   if (fc->isOutputActive()) return false;	// Don't trim while in the middle of figuring out return value
 
-  patchlist.push_front(PatchRecord());		// Push to the front of the patch list
-  patchlist.front().type = PatchRecord::push_patch;
-  patchlist.front().patchOp = op;
-  patchlist.front().in1 = rvn;
+  addPush(op,rvn);
   // pullcount += 1;		// This is a push NOT a pull
   return true;
 }
@@ -655,10 +652,7 @@ bool SubvariableFlow::traceBackward(ReplaceVarnode *rvn)
   case CPUI_INT_SEXT:
     if ((rvn->mask & calc_mask(op->getIn(0)->getSize())) != rvn->mask) {
       if ((rvn->mask & 1)!=0 && flowsize > op->getIn(0)->getSize()) {
-	patchlist.push_front(PatchRecord());		// Push to the front of the patch list
-	patchlist.front().type = PatchRecord::push_patch;
-	patchlist.front().patchOp = op;
-	patchlist.front().in1 = rvn;
+	addPush(op,rvn);
 	return true;
       }
       break;	       // Check if subvariable comes through extension
@@ -903,6 +897,13 @@ bool SubvariableFlow::traceBackwardSext(ReplaceVarnode *rvn)
       if (!createLink(rop,rvn->mask,i,op->getIn(i))) // Same inputs and mask
 	return false;
     return true;
+  case CPUI_INT_ZEXT:
+    if (op->getIn(0)->getSize() < flowsize) {
+      // zero extension from a smaller size still acts as a signed extension
+      addPush(op,rvn);
+      return true;
+    }
+    break;
   case CPUI_INT_SEXT:
     if (flowsize != op->getIn(0)->getSize()) return false;
     rop = createOp(CPUI_COPY,1,rvn);
@@ -1037,6 +1038,21 @@ void SubvariableFlow::createNewOut(ReplaceOp *rop,uintb mask)
   res->def = rop;
 }
 
+/// \brief Mark an operation where original data-flow is being pushed into a subgraph variable
+///
+/// The operation is not manipulating the logical value, but it produces a variable containing
+/// the logical value. The original op will not change but will just produce a smaller value.
+/// \param pushOp is the operation to mark
+/// \param rvn is the output variable holding the logical value
+void SubvariableFlow::addPush(PcodeOp *pushOp,ReplaceVarnode *rvn)
+
+{
+  patchlist.push_front(PatchRecord());		// Push to the front of the patch list
+  patchlist.front().type = PatchRecord::push_patch;
+  patchlist.front().patchOp = pushOp;
+  patchlist.front().in1 = rvn;
+}
+
 /// \brief Mark an operation where a subgraph variable is naturally copied into the original data-flow
 ///
 /// If the operations naturally takes the given logical value as input but the output
diff --git a/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.hh b/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.hh
index d659eb0f59..cdf80a6572 100644
--- a/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.hh
+++ b/Ghidra/Features/Decompiler/src/decompile/cpp/subflow.hh
@@ -105,6 +105,7 @@ class SubvariableFlow {
   bool traceBackwardSext(ReplaceVarnode *rvn);	///< Trace logical data-flow backward assuming sign-extensions
   bool createLink(ReplaceOp *rop,uintb mask,int4 slot,Varnode *vn);
   bool createCompareBridge(PcodeOp *op,ReplaceVarnode *inrvn,int4 slot,Varnode *othervn);
+  void addPush(PcodeOp *pushOp,ReplaceVarnode *rvn);
   void addTerminalPatch(PcodeOp *pullop,ReplaceVarnode *rvn);
   void addTerminalPatchSameOp(PcodeOp *pullop,ReplaceVarnode *rvn,int4 slot);
   void addBooleanPatch(PcodeOp *pullop,ReplaceVarnode *rvn,int4 slot);