[Metal] Add experimental Metal support (#6805)

This adds a new `-metal` flag to DXC which can be used to generate
Metal's IR directly from DXC after compilation. There are some
limitations in this flag which are worth noting:

1) It does not support library shaders (yet)
2) It does not support disassembly (yet)
3) It is _wildly_ under tested because wtihout (2) we can't do anything
to really verify correct output (yay?)

Author: llvm-beanz

README.md

@@ -34,6 +34,16 @@ Development kits containing only the dxc.exe driver app, the dxcompiler.dll, and
 
 As an example of community contribution, this project can also target the [SPIR-V](https://www.khronos.org/registry/spir-v/) intermediate representation. Please see the [doc](docs/SPIR-V.rst) for how HLSL features are mapped to SPIR-V, and the [wiki](https://github.com/microsoft/DirectXShaderCompiler/wiki/SPIR%E2%80%90V-CodeGen) page for how to build, use, and contribute to the SPIR-V CodeGen.
 
+### Metal CodeGen
+
+When built from source DXC can utilize the [Metal Shader
+Converter](https://developer.apple.com/metal/shader-converter/) if it is
+available during build and configuration time. This allows DXC to generate Metal
+shader libraries directly using the `-metal` flag.
+
+Note: DXC cannot currently disassemble Metal shaders so the `-Fc` flag cannot be
+used in conjunction with the `-Fo` flag.
+
 ## Building Sources
 
 See the full documentation for [Building and testing DXC](docs/BuildingAndTestingDXC.rst) for detailed instructions.

cmake/config-ix.cmake

@@ -568,3 +568,12 @@ else()
 endif()
 
 string(REPLACE " " ";" LLVM_BINDINGS_LIST "${LLVM_BINDINGS}")
+
+# HLSL Change Begin - Metal IR Converter
+find_package(MetalIRConverter)
+if (METAL_IRCONVERTER_FOUND)
+  set(ENABLE_METAL_CODEGEN On)
+  message(STATUS "Enabling Metal Support")
+  add_definitions(-DENABLE_METAL_CODEGEN)
+endif()
+# HLSL Change End - Metal IR Converter

cmake/modules/FindMetalIRConverter.cmake

@@ -0,0 +1,16 @@
+find_path(METAL_IRCONVERTER_INCLUDE_DIR metal_irconverter.h
+          HINTS /usr/local/include/metal_irconverter
+          DOC "Path to metal IR converter headers"
+          )
+
+find_library(METAL_IRCONVERTER_LIB NAMES metalirconverter
+  PATH_SUFFIXES lib
+  )
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(METAL_IRCONVERTER
+                                    REQUIRED_VARS METAL_IRCONVERTER_LIB METAL_IRCONVERTER_INCLUDE_DIR)
+
+message(STATUS "Metal IR Converter Include Dir: ${METAL_IRCONVERTER_INCLUDE_DIR}")
+message(STATUS "Metal IR Converter Library: ${METAL_IRCONVERTER_LIB}")
+mark_as_advanced(METAL_IRCONVERTER_LIB METAL_IRCONVERTER_INCLUDE_DIR)

include/dxc/Support/HLSLOptions.h

@@ -274,6 +274,8 @@ class DxcOpts {
       SpirvOptions; // All SPIR-V CodeGen-related options
 #endif
   // SPIRV Change Ends
+
+  bool GenMetal = false; // OPT_metal
 };
 
 /// Use this class to capture, convert and handle the lifetime for the

include/dxc/Support/HLSLOptions.td

@@ -346,6 +346,11 @@ def disable_exception_handling : Flag<["-", "/"], "disable-exception-handling">,
 def skip_serialization : Flag<["-", "/"], "skip-serialization">, Group<hlslcore_Group>, Flags<[CoreOption, HelpHidden]>,
   HelpText<"Return a module interface instead of serialized output">;
 
+def metal : Flag<["-"], "metal">,
+            Group<spirv_Group>,
+            Flags<[CoreOption, DriverOption]>,
+            HelpText<"Generate Metal code">;
+
 // SPIRV Change Starts
 def spirv : Flag<["-"], "spirv">, Group<spirv_Group>, Flags<[CoreOption, DriverOption]>,
   HelpText<"Generate SPIR-V code">;

lib/DxcSupport/HLSLOptions.cpp

@@ -1089,6 +1089,8 @@ int ReadDxcOpts(const OptTable *optionTable, unsigned flagsToInclude,
 
   addDiagnosticArgs(Args, OPT_W_Group, OPT_W_value_Group, opts.Warnings);
 
+  opts.GenMetal = Args.hasFlag(OPT_metal, OPT_INVALID, false);
+
   // SPIRV Change Starts
 #ifdef ENABLE_SPIRV_CODEGEN
   opts.GenSPIRV = Args.hasFlag(OPT_spirv, OPT_INVALID, false);
@@ -1313,6 +1315,21 @@ int ReadDxcOpts(const OptTable *optionTable, unsigned flagsToInclude,
 #endif // ENABLE_SPIRV_CODEGEN
   // SPIRV Change Ends
 
+#ifndef ENABLE_METAL_CODEGEN
+  if (opts.GenMetal) {
+    errors << "Metal CodeGen not available. "
+              "Please rebuild with Metal IR Converter installed.";
+    return 1;
+  }
+#endif
+
+  if (opts.GenMetal) {
+    if (!opts.AssemblyCode.empty() || opts.OutputObject.empty()) {
+      errors << "Disassembly of Metal IR not supported (yet).";
+      return 1;
+    }
+  }
+
   // Validation for DebugInfo here because spirv uses same DebugInfo opt,
   // and legacy wrappers will add EmbedDebug in this case, leading to this
   // failing if placed before spirv path sets DebugInfo to true.

tools/clang/test/DXC/metal.test

@@ -0,0 +1,7 @@
+// REQUIRES: metal
+
+// Metal libraries are LLVM bitcode. This check inspects the magic number from
+// the metal library output.
+// RUN: %dxc %S/Inputs/smoke.hlsl  /T ps_6_0 -metal -Fo Tmp.metal
+// RUN: head -c 4 Tmp.metal | FileCheck -check-prefix=MTL %s
+// MTL: {{^MTLB}}

tools/clang/test/DXC/no_metal.test

@@ -0,0 +1,4 @@
+// UNSUPPORTED: metal
+
+// RUN:not %dxc %S/Inputs/smoke.hlsl  /T ps_6_0 -metal 2>&1 | FileCheck %s
+// CHECK:Metal CodeGen not available

tools/clang/test/DXC/no_metal_disassembly.test

@@ -0,0 +1,7 @@
+// REQUIRES: metal
+
+// These cases both fail because the shader converter library cannot emit
+// textual IR.
+// RUN: not %dxc %S/Inputs/smoke.hlsl  /T ps_6_0 -metal -Fo Tmp.metal -Fc Tmp.air 2>&1 | FileCheck %s
+// RUN: not %dxc %S/Inputs/smoke.hlsl  /T ps_6_0 -metal 2>&1 | FileCheck %s
+// CHECK: Disassembly of Metal IR not supported (yet).

tools/clang/test/lit.cfg

@@ -504,6 +504,9 @@ if config.enable_backtrace == "1":
 if config.spirv:
     config.available_features.add("spirv")
 
+if config.metal:
+    config.available_features.add("metal")
+
 # Check supported dxil version
 def get_dxil_version():
     result = subprocess.run([lit.util.which('dxc', llvm_tools_dir), "--version"], stdout=subprocess.PIPE)

tools/clang/test/lit.site.cfg.in

@@ -22,6 +22,7 @@ config.enable_backtrace = "@ENABLE_BACKTRACES@"
 config.host_arch = "@HOST_ARCH@"
 config.spirv = "@ENABLE_SPIRV_CODEGEN@" =="ON"
 config.hlsl_headers_dir = "@HLSL_HEADERS_DIR@" # HLSL change
+config.metal = "@ENABLE_METAL_CODEGEN@".upper() == "ON" # HLSL change
 
 # Support substitution of the tools and libs dirs with user parameters. This is
 # used when we can't determine the tool dir at configuration time.

tools/clang/tools/dxcompiler/CMakeLists.txt

@@ -136,6 +136,14 @@ target_link_libraries(dxcompiler PRIVATE ${LIBRARIES})
 if (ENABLE_SPIRV_CODEGEN)
   target_link_libraries(dxcompiler PRIVATE clangSPIRV)
 endif (ENABLE_SPIRV_CODEGEN)
+if (ENABLE_METAL_CODEGEN)
+  target_link_libraries(dxcompiler PRIVATE ${METAL_IRCONVERTER_LIB})
+  target_include_directories(dxcompiler PRIVATE ${METAL_IRCONVERTER_INCLUDE_DIR})
+
+  get_filename_component(METAL_IRCONVERTER_LIB_DIR ${METAL_IRCONVERTER_LIB} DIRECTORY CACHE)
+  set_property(TARGET dxcompiler APPEND_STRING
+               PROPERTY LINK_FLAGS " -Wl,-rpath,${METAL_IRCONVERTER_LIB_DIR}")
+endif (ENABLE_METAL_CODEGEN)
 include_directories(AFTER ${LLVM_INCLUDE_DIR}/dxc/Tracing ${DIASDK_INCLUDE_DIRS} ${HLSL_VERSION_LOCATION})
 include_directories(${LLVM_SOURCE_DIR}/tools/clang/tools/dxcvalidator)
 

tools/clang/tools/dxcompiler/dxcompilerobj.cpp

@@ -71,6 +71,10 @@
 #include "clang/Basic/Version.h"
 #endif // SUPPORT_QUERY_GIT_COMMIT_INFO
 
+#ifdef ENABLE_METAL_CODEGEN
+#include "metal_irconverter.h"
+#endif
+
 #define CP_UTF16 1200
 
 using namespace llvm;
@@ -817,6 +821,10 @@ class DxcCompiler : public IDxcCompiler3,
         }
         compiler.getLangOpts().IsHLSLLibrary = opts.IsLibraryProfile();
 
+        if (compiler.getLangOpts().IsHLSLLibrary && opts.GenMetal)
+          return ErrorWithString("Shader libraries unsupported in Metal (yet)",
+                                 riid, ppResult);
+
         // Clear entry function if library target
         if (compiler.getLangOpts().IsHLSLLibrary)
           compiler.getLangOpts().HLSLEntryFunction =
@@ -1107,7 +1115,86 @@ class DxcCompiler : public IDxcCompiler3,
                                               &pHashBlob));
             IFT(pResult->SetOutputObject(DXC_OUT_SHADER_HASH, pHashBlob));
           } // SUCCEEDED(valHR)
-        }   // compileOK && !opts.CodeGenHighLevel
+#ifdef ENABLE_METAL_CODEGEN
+          // This is a bit hacky because we don't currently have a good way to
+          // disassemble AIR.
+          if (opts.GenMetal && produceFullContainer &&
+              !opts.OutputObject.empty()) {
+            IRCompiler *MetalCompiler = IRCompilerCreate();
+            IRCompilerSetEntryPointName(
+                MetalCompiler,
+                compiler.getCodeGenOpts().HLSLEntryFunction.c_str());
+
+            IRObject *DXILObj = IRObjectCreateFromDXIL(
+                static_cast<const uint8_t *>(pOutputBlob->GetBufferPointer()),
+                pOutputBlob->GetBufferSize(), IRBytecodeOwnershipNone);
+
+            // Compile DXIL to Metal IR:
+            IRError *Error = nullptr;
+            IRObject *AIR = IRCompilerAllocCompileAndLink(MetalCompiler, NULL,
+                                                          DXILObj, &Error);
+
+            if (!AIR) {
+              IRObjectDestroy(DXILObj);
+              IRCompilerDestroy(MetalCompiler);
+              IRErrorDestroy(Error);
+              return ErrorWithString(
+                  "Error occurred in Metal Shader Conversion", riid, ppResult);
+            }
+
+            IRMetalLibBinary *MetalLib = IRMetalLibBinaryCreate();
+            IRShaderStage Stage = IRShaderStageInvalid;
+            const ShaderModel *SM = hlsl::ShaderModel::GetByName(
+                compiler.getLangOpts().HLSLProfile);
+            switch (SM->GetKind()) {
+            case DXIL::ShaderKind::Vertex:
+              Stage = IRShaderStageVertex;
+              break;
+            case DXIL::ShaderKind::Pixel:
+              Stage = IRShaderStageFragment;
+              break;
+            case DXIL::ShaderKind::Hull:
+              Stage = IRShaderStageHull;
+              break;
+            case DXIL::ShaderKind::Domain:
+              Stage = IRShaderStageDomain;
+              break;
+            case DXIL::ShaderKind::Mesh:
+              Stage = IRShaderStageMesh;
+              break;
+            case DXIL::ShaderKind::Amplification:
+              Stage = IRShaderStageAmplification;
+              break;
+            case DXIL::ShaderKind::Geometry:
+              Stage = IRShaderStageGeometry;
+              break;
+            case DXIL::ShaderKind::Compute:
+              Stage = IRShaderStageCompute;
+              break;
+            }
+            assert(Stage != IRShaderStageInvalid &&
+                   "Library targets not supported for Metal (yet).");
+            IRObjectGetMetalLibBinary(AIR, Stage, MetalLib);
+            size_t MetalLibSize = IRMetalLibGetBytecodeSize(MetalLib);
+            std::unique_ptr<uint8_t[]> MetalLibBytes =
+                std::unique_ptr<uint8_t[]>(new uint8_t[MetalLibSize]);
+            IRMetalLibGetBytecode(MetalLib, MetalLibBytes.get());
+
+            // Store the metallib to custom format or disk, or use to create a
+            // MTLLibrary.
+
+            CComPtr<IDxcBlob> MetalBlob;
+            IFT(hlsl::DxcCreateBlobOnHeapCopy(
+                MetalLibBytes.get(), (uint32_t)MetalLibSize, &MetalBlob));
+            std::swap(pOutputBlob, MetalBlob);
+
+            IRMetalLibBinaryDestroy(MetalLib);
+            IRObjectDestroy(DXILObj);
+            IRObjectDestroy(AIR);
+            IRCompilerDestroy(MetalCompiler);
+          }
+#endif
+        } // compileOK && !opts.CodeGenHighLevel
       }
 
       std::string remarks;