1 files changed, 115 insertions, 0 deletions
diff --git a/src/vm/disassembler.h b/src/vm/disassembler.h
new file mode 100644
index 0000000000..1b3bf46e0e
--- /dev/null
+++ b/src/vm/disassembler.h
@@ -0,0 +1,115 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#ifndef __DISASSEMBLER_H__
+#define __DISASSEMBLER_H__
+
+#include "switches.h"
+
+#define USE_COREDISTOOLS_DISASSEMBLER 0
+#define USE_MSVC_DISASSEMBLER 0
+#ifdef HAVE_GCCOVER
+    #if defined(FEATURE_CORECLR)
+        // COREDISTOOLS disassembler only supports amd64 and x86, so if this is
+        // CoreCLR but not amd64 and not x86, we will fall out of this check and not
+        // set USE_DISASSEMBLER.
+        #if defined(_TARGET_AMD64_) || defined(_TARGET_X86_)
+            #undef USE_COREDISTOOLS_DISASSEMBLER
+            #define USE_COREDISTOOLS_DISASSEMBLER 1
+        #endif
+    #elif defined(_TARGET_AMD64_) || defined(_TARGET_X86_)
+        #undef USE_MSVC_DISASSEMBLER
+        #define USE_MSVC_DISASSEMBLER 1
+    #endif // defined(FEATURE_CORECLR) || defined(_TARGET_AMD64_) || defined(_TARGET_X86_)
+#endif // HAVE_GCCOVER
+
+#if USE_COREDISTOOLS_DISASSEMBLER
+#include "coredistools.h"
+#endif
+
+#if USE_COREDISTOOLS_DISASSEMBLER || USE_MSVC_DISASSEMBLER
+    #define USE_DISASSEMBLER 1
+#else
+    #define USE_DISASSEMBLER 0
+#endif
+
+#if USE_DISASSEMBLER
+
+#if USE_MSVC_DISASSEMBLER
+#undef free
+
+// This pragma is needed because public\vc\inc\xiosbase contains
+// a static local variable
+#pragma warning(disable : 4640)
+#include "msvcdis.h"
+#pragma warning(default : 4640)
+
+#include "disx86.h"
+
+#define free(memblock) Use_free(memblock)
+#endif // USE_MSVC_DISASSEMBLER
+
+enum class InstructionType : UINT8
+{
+    Unknown,
+    Call_DirectUnconditional,
+    Call_IndirectUnconditional,
+    Branch_IndirectUnconditional
+};
+
+class InstructionInfo;
+
+// Wraps the MSVC disassembler or the coredistools disassembler
+class Disassembler
+{
+#if USE_COREDISTOOLS_DISASSEMBLER
+private:
+    typedef CorDisasm ExternalDisassembler;
+#elif USE_MSVC_DISASSEMBLER
+private:
+    typedef DIS ExternalDisassembler;
+#endif // USE_COREDISTOOLS_DISASSEMBLER || USE_MSVC_DISASSEMBLER
+
+#if defined(_TARGET_AMD64_) || defined(_TARGET_X86_)
+public:
+    static bool IsRexPrefix(UINT8 potentialRexByte);
+    static UINT8 DecodeModFromModRm(UINT8 modRm);
+    static UINT8 DecodeRegOrOpCodeFromModRm(UINT8 modRm);
+    static UINT8 DecodeRmFromModRm(UINT8 modRm);
+#endif // defined(_TARGET_AMD64_) || defined(_TARGET_X86_)
+
+public:
+    static bool IsAvailable();
+    static void StaticInitialize();
+    static void StaticClose();
+
+public:
+    Disassembler();
+    ~Disassembler();
+
+public:
+    SIZE_T DisassembleInstruction(const UINT8 *code, SIZE_T codeLength, InstructionType *instructionTypeRef) const;
+    static InstructionType DetermineInstructionType(
+    #if USE_COREDISTOOLS_DISASSEMBLER
+        const UINT8 *instructionCode, SIZE_T instructionCodeLength
+    #elif USE_MSVC_DISASSEMBLER
+        ExternalDisassembler::TRMT terminationType
+    #endif // USE_COREDISTOOLS_DISASSEMBLER || USE_MSVC_DISASSEMBLER
+        );
+
+#if USE_COREDISTOOLS_DISASSEMBLER
+private:
+    static HMODULE s_libraryHandle;
+    static InitDisasm_t *External_InitDisasm;
+    static FinishDisasm_t *External_FinishDisasm;
+    static DisasmInstruction_t *External_DisasmInstruction;
+#endif // USE_COREDISTOOLS_DISASSEMBLER
+
+private:
+    static ExternalDisassembler *s_availableExternalDisassembler;
+    ExternalDisassembler *m_externalDisassembler;
+};
+
+#endif // USE_DISASSEMBLER
+#endif // __DISASSEMBLER_H__