From ae7919722a73430ca76d764038daa024ae03d79c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Tue, 3 Feb 2015 13:52:23 +0100
Subject: [PATCH] Workaround for linker removing JIT callback functions

---
 libevmjit-cpp/JitVM.cpp | 16 +++++-----------
 libevmjit/Common.h      | 14 ++++++++------
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/libevmjit-cpp/JitVM.cpp b/libevmjit-cpp/JitVM.cpp
index 613b5031c..413525e5a 100644
--- a/libevmjit-cpp/JitVM.cpp
+++ b/libevmjit-cpp/JitVM.cpp
@@ -9,6 +9,8 @@ namespace dev
 namespace eth
 {
 
+extern "C" void env_sload(); // fake declaration for linker symbol stripping workaround, see a call below
+
 bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 {
 	using namespace jit;
@@ -58,6 +60,9 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 		BOOST_THROW_EXCEPTION(StackTooSmall());
 	case ReturnCode::BadInstruction:
 		BOOST_THROW_EXCEPTION(BadInstruction());
+	case ReturnCode::LinkerWorkaround:	// never happens
+		env_sload();					// but forces linker to include env_* JIT callback functions
+		break;
 	default:
 		break;
 	}
@@ -68,14 +73,3 @@ bytesConstRef JitVM::go(ExtVMFace& _ext, OnOpFunc const&, uint64_t)
 
 }
 }
-
-namespace
-{
-	// MSVS linker ignores export symbols in Env.cpp if nothing points at least one of them
-	extern "C" void env_sload();
-	void linkerWorkaround() 
-	{ 
-		env_sload();
-		(void)&linkerWorkaround; // suppress unused function warning from GCC
-	}
-}
diff --git a/libevmjit/Common.h b/libevmjit/Common.h
index 7383b9f93..d629f25ad 100644
--- a/libevmjit/Common.h
+++ b/libevmjit/Common.h
@@ -2,12 +2,12 @@
 
 #include <vector>
 #include <tuple>
-#include <cstdint>
-
-#ifdef _MSC_VER
-#define EXPORT __declspec(dllexport)
-#else
-#define EXPORT
+#include <cstdint>
+
+#ifdef _MSC_VER
+#define EXPORT __declspec(dllexport)
+#else
+#define EXPORT
 #endif
 
 namespace dev
@@ -39,6 +39,8 @@ enum class ReturnCode
 	LLVMLinkError = -7,
 
 	UnexpectedException = -8,
+
+	LinkerWorkaround = -299,
 };
 
 /// Representation of 256-bit value binary compatible with LLVM i256