From 5841af2db8e8dcf4e0da0c438ac040c5fa90038b Mon Sep 17 00:00:00 2001
From: Rusty Wagner <rusty@vector35.com>
Date: Tue, 21 Aug 2018 15:47:34 -0400
Subject: Add return hint MLIL instruction (used in intermediate stages, not
 emitted in final forms)

---
 binaryninjaapi.h             | 1 +
 binaryninjacore.h            | 1 +
 mediumlevelilinstruction.cpp | 9 +++++++++
 mediumlevelilinstruction.h   | 4 ++++
 python/mediumlevelil.py      | 1 +
 5 files changed, 16 insertions(+)

diff --git a/binaryninjaapi.h b/binaryninjaapi.h
index 32ed38d2..e0406592 100644
--- a/binaryninjaapi.h
+++ b/binaryninjaapi.h
@@ -3187,6 +3187,7 @@ namespace BinaryNinja
 		ExprId Jump(ExprId dest, const ILSourceLocation& loc = ILSourceLocation());
 		ExprId JumpTo(ExprId dest, const std::vector<BNMediumLevelILLabel*>& targets,
 			const ILSourceLocation& loc = ILSourceLocation());
+		ExprId ReturnHint(ExprId dest, const ILSourceLocation& loc = ILSourceLocation());
 		ExprId Call(const std::vector<Variable>& output, ExprId dest, const std::vector<ExprId>& params,
 			const ILSourceLocation& loc = ILSourceLocation());
 		ExprId CallUntyped(const std::vector<Variable>& output, ExprId dest, const std::vector<Variable>& params,
diff --git a/binaryninjacore.h b/binaryninjacore.h
index c8fb9f8f..e029f208 100644
--- a/binaryninjacore.h
+++ b/binaryninjacore.h
@@ -851,6 +851,7 @@ extern "C"
 		MLIL_LOW_PART,
 		MLIL_JUMP,
 		MLIL_JUMP_TO,
+		MLIL_RET_HINT, // Intermediate stages, does not appear in final forms
 		MLIL_CALL, // Not valid in SSA form (see MLIL_CALL_SSA)
 		MLIL_CALL_UNTYPED, // Not valid in SSA form (see MLIL_CALL_UNTYPED_SSA)
 		MLIL_CALL_OUTPUT, // Only valid within MLIL_CALL, MLIL_SYSCALL, MLIL_TAILCALL family instructions
diff --git a/mediumlevelilinstruction.cpp b/mediumlevelilinstruction.cpp
index 9cf82b08..93587c34 100644
--- a/mediumlevelilinstruction.cpp
+++ b/mediumlevelilinstruction.cpp
@@ -122,6 +122,7 @@ unordered_map<BNMediumLevelILOperation, vector<MediumLevelILOperandUsage>>
 		{MLIL_ADDRESS_OF_FIELD, {SourceVariableMediumLevelOperandUsage, OffsetMediumLevelOperandUsage}},
 		{MLIL_JUMP, {DestExprMediumLevelOperandUsage}},
 		{MLIL_JUMP_TO, {DestExprMediumLevelOperandUsage, TargetListMediumLevelOperandUsage}},
+		{MLIL_RET_HINT, {DestExprMediumLevelOperandUsage}},
 		{MLIL_CALL, {OutputVariablesMediumLevelOperandUsage, DestExprMediumLevelOperandUsage,
 			ParameterExprsMediumLevelOperandUsage}},
 		{MLIL_CALL_UNTYPED, {OutputVariablesSubExprMediumLevelOperandUsage, DestExprMediumLevelOperandUsage,
@@ -1322,6 +1323,7 @@ void MediumLevelILInstruction::VisitExprs(const std::function<bool(const MediumL
 	case MLIL_BOOL_TO_INT:
 	case MLIL_JUMP:
 	case MLIL_JUMP_TO:
+	case MLIL_RET_HINT:
 	case MLIL_IF:
 	case MLIL_UNIMPL_MEM:
 	case MLIL_LOAD:
@@ -1591,6 +1593,7 @@ ExprId MediumLevelILInstruction::CopyTo(MediumLevelILFunction* dest,
 	case MLIL_LOW_PART:
 	case MLIL_BOOL_TO_INT:
 	case MLIL_JUMP:
+	case MLIL_RET_HINT:
 	case MLIL_UNIMPL_MEM:
 	case MLIL_FSQRT:
 	case MLIL_FNEG:
@@ -2497,6 +2500,12 @@ ExprId MediumLevelILFunction::JumpTo(ExprId dest, const vector<BNMediumLevelILLa
 }
 
 
+ExprId MediumLevelILFunction::ReturnHint(ExprId dest, const ILSourceLocation& loc)
+{
+	return AddExprWithLocation(MLIL_RET_HINT, loc, 0, dest);
+}
+
+
 ExprId MediumLevelILFunction::Call(const vector<Variable>& output, ExprId dest,
 	const vector<ExprId>& params, const ILSourceLocation& loc)
 {
diff --git a/mediumlevelilinstruction.h b/mediumlevelilinstruction.h
index b37b8832..d39ea87d 100644
--- a/mediumlevelilinstruction.h
+++ b/mediumlevelilinstruction.h
@@ -814,6 +814,10 @@ namespace BinaryNinja
 		MediumLevelILInstruction GetDestExpr() const { return GetRawOperandAsExpr(0); }
 		MediumLevelILIndexList GetTargetList() const { return GetRawOperandAsIndexList(1); }
 	};
+	template <> struct MediumLevelILInstructionAccessor<MLIL_RET_HINT>: public MediumLevelILInstructionBase
+	{
+		MediumLevelILInstruction GetDestExpr() const { return GetRawOperandAsExpr(0); }
+	};
 
 	template <> struct MediumLevelILInstructionAccessor<MLIL_CALL>: public MediumLevelILInstructionBase
 	{
diff --git a/python/mediumlevelil.py b/python/mediumlevelil.py
index cfa8f900..774231ab 100644
--- a/python/mediumlevelil.py
+++ b/python/mediumlevelil.py
@@ -128,6 +128,7 @@ class MediumLevelILInstruction(object):
 		MediumLevelILOperation.MLIL_LOW_PART: [("src", "expr")],
 		MediumLevelILOperation.MLIL_JUMP: [("dest", "expr")],
 		MediumLevelILOperation.MLIL_JUMP_TO: [("dest", "expr"), ("targets", "int_list")],
+		MediumLevelILOperation.MLIL_RET_HINT: [("dest", "expr")],
 		MediumLevelILOperation.MLIL_CALL: [("output", "var_list"), ("dest", "expr"), ("params", "expr_list")],
 		MediumLevelILOperation.MLIL_CALL_UNTYPED: [("output", "expr"), ("dest", "expr"), ("params", "expr"), ("stack", "expr")],
 		MediumLevelILOperation.MLIL_CALL_OUTPUT: [("dest", "var_list")],
-- 
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