gsdx-dx: Load D3DCompiler dll at runtime

D3DCompiler_47.dll will be loaded for Windows 8.1 and above (and maybe
Windows 7 devs), D3DCompiler_43.dll will be loaded for Windows 7 and
below.

plugins/GSdx/GS.cpp

@@ -132,6 +132,10 @@ EXPORT_C_(int) GSinit()
 		return -1;
 	}
 
+	if (!GSDeviceDX::LoadD3DCompiler())
+	{
+		return -1;
+	}
 #endif
 
 	return 0;
@@ -156,6 +160,8 @@ EXPORT_C GSshutdown()
 		s_hr = E_FAIL;
 	}
 
+	GSDeviceDX::FreeD3DCompiler();
+
 #endif
 }
 

plugins/GSdx/GSDeviceDX.cpp

@@ -22,6 +22,11 @@
 #include "stdafx.h"
 #include "GSdx.h"
 #include "GSDeviceDX.h"
+#include <VersionHelpers.h>
+
+HMODULE GSDeviceDX::s_d3d_compiler_dll = nullptr;
+decltype(&D3DCompile) GSDeviceDX::s_pD3DCompile = nullptr;
+bool GSDeviceDX::s_old_d3d_compiler_dll;
 
 GSDeviceDX::GSDeviceDX()
 {
@@ -35,6 +40,48 @@ GSDeviceDX::~GSDeviceDX()
 {
 }
 
+bool GSDeviceDX::LoadD3DCompiler()
+{
+	// Windows 8.1 and later come with the latest d3dcompiler_47.dll, but
+	// Windows 7 devs might also have the dll available for use (which will
+	// have to be placed in the application directory)
+	s_d3d_compiler_dll = LoadLibraryEx(D3DCOMPILER_DLL, nullptr, LOAD_LIBRARY_SEARCH_APPLICATION_DIR | LOAD_LIBRARY_SEARCH_SYSTEM32);
+
+	// Windows Vista and 7 can use the older version. If the previous LoadLibrary
+	// call fails on Windows 8.1 and later, then the user's system is likely
+	// broken.
+	if (s_d3d_compiler_dll)
+	{
+		s_old_d3d_compiler_dll = false;
+	}
+	else
+	{
+		if (!IsWindows8Point1OrGreater())
+			s_d3d_compiler_dll = LoadLibraryEx("D3DCompiler_43.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
+
+		if (s_d3d_compiler_dll == nullptr)
+			return false;
+
+		s_old_d3d_compiler_dll = true;
+	}
+
+	s_pD3DCompile = reinterpret_cast<decltype(&D3DCompile)>(GetProcAddress(s_d3d_compiler_dll, "D3DCompile"));
+	if (s_pD3DCompile)
+		return true;
+
+	FreeLibrary(s_d3d_compiler_dll);
+	s_d3d_compiler_dll = nullptr;
+	return false;
+}
+
+void GSDeviceDX::FreeD3DCompiler()
+{
+	s_pD3DCompile = nullptr;
+	if (s_d3d_compiler_dll)
+		FreeLibrary(s_d3d_compiler_dll);
+	s_d3d_compiler_dll = nullptr;
+}
+
 GSTexture* GSDeviceDX::FetchSurface(int type, int w, int h, bool msaa, int format)
 {
 	if(m_msaa < 2)

plugins/GSdx/GSDeviceDX.h

@@ -278,6 +278,12 @@ protected:
 	uint32 m_msaa;
 	DXGI_SAMPLE_DESC m_msaa_desc;
 
+	static HMODULE s_d3d_compiler_dll;
+	static decltype(&D3DCompile) s_pD3DCompile;
+	// Older version doesn't support D3D_COMPILE_STANDARD_FILE_INCLUDE, which
+	// could be useful for external shaders.
+	static bool s_old_d3d_compiler_dll;
+
 	GSTexture* FetchSurface(int type, int w, int h, bool msaa, int format);
 
 public:
@@ -297,6 +303,9 @@ public:
 	virtual bool HasStencil() = 0;
 	virtual bool HasDepth32() = 0;
 
+	static bool LoadD3DCompiler();
+	static void FreeD3DCompiler();
+
 	template<class T> void PrepareShaderMacro(vector<T>& dst, const T* src)
 	{
 		dst.clear();

plugins/GSdx/stdafx.h

@@ -37,6 +37,7 @@
 #include <commctrl.h>
 #include <commdlg.h>
 #include <shellapi.h>
+#include <d3dcompiler.h>
 #include <d3d11.h>
 #include <d3dx11.h>
 #include <d3d9.h>