Add feedback why the backward search has been stopped

irdb-libs/ir_builders/back_search.hpp

@@ -59,17 +59,19 @@ void calc_preds(FileIR_t* firp)
 }
 
 
-// search for an expression in prior instructions.
-bool backup_until(const string &insn_type_regex_str, // what to search for 
+// search for an expression in prior instructions. Return whether expression was found.
+// If an assignment is found, stopped_because_set is set to this instruction and false is returned
+bool backup_until_or_move(const string &insn_type_regex_str, // what to search for
 		  Instruction_t *& prev,             // output param -- the instruction we found.
 		  Instruction_t* orig,               // where to start the search.
+          Instruction_t *& stopped_because_set, // output param -- the instruction that stopped the search because of stop_if_set. nullptr if the search was not stopped because of this reason
 		  const string & stop_if_set="",     // stop if an operand that's written matches this expression.
 		  const string & stop_if_opcode="",  // stop if an opcode matches this expression
 		  bool recursive=false,              // search recursively?
 		  uint32_t max_insns=10000u,         // max number of instructions to search through.
 		  uint32_t max_recursions=5u)        // make number of blocks to recusive into
 {
-
+    stopped_because_set = static_cast<Instruction_t *>(nullptr);
 	const auto find_or_build_regex=[&] (const string& s) -> regex_t&
 		{
 			// declare a freer for regexs so they go away when the program ends.
@@ -130,8 +132,10 @@ bool backup_until(const string &insn_type_regex_str, // what to search for
 		{
 			for(const auto &operand : disasm->getOperands())
 			{
-				if(operand->isWritten() && regexec(&stop_operand_expression, operand->getString().c_str(), 0, nullptr, 0) == 0)
-					return false;
+				if(operand->isWritten() && regexec(&stop_operand_expression, operand->getString().c_str(), 0, nullptr, 0) == 0) {
+                    stopped_because_set = prev;
+                    return false;
+                }
 			}
 		}
 		// if we have a stop_if_opcode expresison, check the opcode to see if it matches.
@@ -156,14 +160,16 @@ bool backup_until(const string &insn_type_regex_str, // what to search for
 			{
 				for(const auto &operand : disasm->getOperands())
 				{
-					if(operand->isWritten() && regexec(&stop_operand_expression, operand->getString().c_str(), 0, nullptr, 0) == 0)
-						return false;
+					if(operand->isWritten() && regexec(&stop_operand_expression, operand->getString().c_str(), 0, nullptr, 0) == 0) {
+                        stopped_because_set = pred;
+                        return false;
+                    }
 				}
 			}
 			// if we have a stop_if_opcode expresison, check the opcode to see if it matches.
 			if(stop_if_opcode!="" && regexec(&stop_opcode_expression, disasm->getMnemonic().c_str(), 0, nullptr, 0) == 0)
 				return false;
-			if(backup_until(insn_type_regex_str, prev, pred, stop_if_set, stop_if_opcode, recursive, max_insns, max_recursions/mypreds.size()))
+			if(backup_until_or_move(insn_type_regex_str, prev, pred, stopped_because_set, stop_if_set, stop_if_opcode, recursive, max_insns, max_recursions/mypreds.size()))
 				return true;
 
 			// reset for next call
@@ -173,5 +179,28 @@ bool backup_until(const string &insn_type_regex_str, // what to search for
 	return false;
 }
 
+// search for an expression in prior instructions.
+bool backup_until(const string &insn_type_regex_str, // what to search for
+                  Instruction_t *& prev,             // output param -- the instruction we found.
+                  Instruction_t* orig,               // where to start the search.
+                  const string & stop_if_set="",     // stop if an operand that's written matches this expression.
+                  const string & stop_if_opcode="",  // stop if an opcode matches this expression
+                  bool recursive=false,              // search recursively?
+                  uint32_t max_insns=10000u,         // max number of instructions to search through.
+                  uint32_t max_recursions=5u)        // make number of blocks to recusive into
+{
+    // This function is just a proxy to keep the old API intact
+    auto discard = static_cast<Instruction_t *>(nullptr);
+
+    return backup_until_or_move(insn_type_regex_str,
+    prev,
+    orig,
+    discard,
+    stop_if_set,
+    stop_if_opcode,
+    recursive,
+    max_insns,
+    max_recursions);
+}
 
 #endif