Merge remote-tracking branch 'origin/GP-3834_JumptableByte'

(Closes #5494)

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

@@ -1030,6 +1030,21 @@ PcodeOp *PathMeld::getEarliestOp(int4 pos) const
   return (PcodeOp *)0;
 }
 
+/// Search for a Varnode in the common path, prior to the given point, defined by a LOAD operation.
+/// \param i is the given point in the path
+/// \return \b true if a LOAD is present
+bool PathMeld::isLoadInPath(int4 i) const
+
+{
+  while(i > 0) {
+    i -= 1;
+    Varnode *vn = commonVn[i];
+    if (!vn->isWritten()) continue;
+    if (vn->getDef()->code() == CPUI_LOAD) return true;
+  }
+  return false;
+}
+
 /// \brief Analyze CBRANCHs leading up to the given basic-block as a potential switch \e guard.
 ///
 /// In general there is only one path to the switch, and the given basic-block will
@@ -1180,8 +1195,10 @@ void JumpBasic::findSmallestNormal(uint4 matchsize)
     calcRange(pathMeld.getVarnode(i),rng);
     sz = rng.getSize();
     if (sz < maxsize) {
-      // Don't let a 1-byte switch variable get thru without a guard
+      // Don't accept a 1-byte switch variable unless there is an explicit guard
-      if ((sz != 256)||(pathMeld.getVarnode(i)->getSize()!=1)) {
+      // or a table lookup between the byte and the indirect jump.
+      // "goto *(#const + byteVar)" should not be interpreted as 256 case switch
+      if (sz != 256 || pathMeld.getVarnode(i)->getSize()!=1 || pathMeld.isLoadInPath(i)) {
 	varnodeIndex = i;
 	maxsize = sz;
 	jrange->setRange(rng);

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

@@ -98,6 +98,7 @@ public:
   Varnode *getOpParent(int4 i) const { return commonVn[ opMeld[i].rootVn ]; }	///< Get the split-point for the i-th PcodeOp
   PcodeOp *getOp(int4 i) const { return opMeld[i].op; }		///< Get the i-th PcodeOp
   PcodeOp *getEarliestOp(int4 pos) const;		///< Find \e earliest PcodeOp that has a specific common Varnode as input
+  bool isLoadInPath(int4 i) const;			///< Return \b true if a LOAD exists in the common path
   bool empty(void) const { return commonVn.empty(); }	///< Return \b true if \b this container holds no paths
 };
 

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

@@ -4630,6 +4630,9 @@ void TypeFactory::decodeAlignmentMap(Decoder &decoder)
     alignMap[sz] = val;
     decoder.closeElement(mapId);
   }
+  if (alignMap.empty())
+    throw LowlevelError("Alignment map empty");
+  alignMap[0] = 1;
   int4 curAlign = 1;
   for(int4 sz=1;sz < alignMap.size();++sz) {
     int4 tmpAlign = alignMap[sz];
@@ -4644,7 +4647,7 @@ void TypeFactory::decodeAlignmentMap(Decoder &decoder)
 void TypeFactory::setDefaultAlignmentMap(void)
 
 {
-  alignMap.resize(9,0);
+  alignMap.resize(9,1);
   alignMap[1] = 1;
   alignMap[2] = 2;
   alignMap[3] = 2;