Add back compat lit test suite, and download older dxil.dll's

include/dxc/Support/dxcapi.extval.h

@@ -7,7 +7,7 @@ class DxcDllExtValidationLoader : public DllLoader {
   // DxCompilerSupport manages the
   // lifetime of dxcompiler.dll, while DxilExtValSupport
   // manages the lifetime of dxil.dll
-  dxc::SpecificDllLoader DxCompilerSupport;
+  dxc::DxCompilerDllLoader DxCompilerSupport;
   dxc::SpecificDllLoader DxilExtValSupport;
   std::string DxilDllPath;
 

include/dxc/Test/DxcTestUtils.h

@@ -13,6 +13,7 @@
 
 #include "dxc/Support/WinIncludes.h"
 
+#include "dxc/Support/dxcapi.extval.h"
 #include "dxc/Support/dxcapi.use.h"
 #include "dxc/dxcapi.h"
 #include "llvm/ADT/ArrayRef.h"
@@ -199,6 +200,8 @@ void GetDxilPart(dxc::DllLoader &dllSupport, IDxcBlob *pProgram,
                  IDxcBlob **pDxilPart);
 std::string DisassembleProgram(dxc::DxCompilerDllLoader &dllSupport,
                                IDxcBlob *pProgram);
+std::string DisassembleProgram(dxc::DxcDllExtValidationLoader &dllSupport,
+                               IDxcBlob *pProgram);
 void SplitPassList(LPWSTR pPassesBuffer, std::vector<LPCWSTR> &passes);
 void MultiByteStringToBlob(dxc::DllLoader &dllSupport, const std::string &val,
                            UINT32 codePoint, IDxcBlob **ppBlob);

tools/clang/test/CMakeLists.txt

@@ -121,8 +121,84 @@ add_lit_testsuites(CLANG ${CMAKE_CURRENT_SOURCE_DIR}
   DEPENDS ${CLANG_TEST_DEPS}
   FOLDER "Clang tests/Suites"
 )
+# -------------------------------------------------------------------------
+# DXIL Backward Compatibility Section
+# -------------------------------------------------------------------------
+
+# Define DXC releases as (NAME VERSION) pairs
+set(DXC_RELEASES
+  dxc_2025_07_14 v1.8.2505.1
+  dxc_2025_05_24 v1.8.2505
+  dxc_2025_02_20 v1.8.2502
+  dxc_2023_08_14 v1.7.2308
+  dxc_2021_12_08 v1.6.2112
+)
+
+# Download a DXC release
+function(add_released_dxc name version)
+  ExternalProject_Add(${name}
+      URL https://github.com/microsoft/DirectXShaderCompiler/releases/download/${version}/${name}.zip
+      DOWNLOAD_DIR ${CMAKE_BINARY_DIR}/tools/clang/test/dxc_releases
+      SOURCE_DIR ${CMAKE_BINARY_DIR}/tools/clang/test/dxc_releases/${version}/${name}
+      CONFIGURE_COMMAND ""
+      BUILD_COMMAND ""
+      INSTALL_COMMAND ""
+  )
+endfunction()
+
+# Iterate over releases
+list(LENGTH DXC_RELEASES DXC_RELEASES_LENGTH)
+math(EXPR num_pairs "${DXC_RELEASES_LENGTH} / 2")
+math(EXPR loop_end "${num_pairs} - 1")
+foreach(i RANGE 0 ${loop_end})
+  math(EXPR idx_name "${i}*2")
+  math(EXPR idx_version "${i}*2 + 1")  
+
+  list(GET DXC_RELEASES ${idx_name} name)
+  list(GET DXC_RELEASES ${idx_version} version)
+
+  add_released_dxc(${name} ${version})
+
+  if(WIN32)
+  # Determine target architecture for DXC binaries
+    if(CMAKE_GENERATOR MATCHES "Visual Studio")
+        # Multi-config generators (VS/Xcode)
+        if(NOT DEFINED CMAKE_GENERATOR_PLATFORM)
+            message(FATAL_ERROR "CMAKE_GENERATOR_PLATFORM not set for multi-config generator")
+        endif()
+        set(TARGET_ARCH ${CMAKE_GENERATOR_PLATFORM})
+    else()
+        # Single-config generators (Ninja, Makefiles)
+        # Use pointer size to guess x86 vs x64
+        if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+            set(TARGET_ARCH x64)
+        elseif(CMAKE_SIZEOF_VOID_P EQUAL 4)
+            set(TARGET_ARCH x86)
+        else()
+            message(FATAL_ERROR "Unknown pointer size: ${CMAKE_SIZEOF_VOID_P}")
+        endif()
+    endif()
+
+    message("TARGET_ARCH IS ${TARGET_ARCH}")
+
+    # Path to dxil.dll for this release
+    set(DXC_PATH ${CMAKE_BINARY_DIR}/tools/clang/test/dxc_releases/${version}/${name}/bin/${TARGET_ARCH}/dxil.dll)
+
+    # Create a lit target for this release
+    add_lit_target("check-clang-${name}" "Running clang regression tests with ${name}\n"
+      ${CMAKE_CURRENT_SOURCE_DIR}
+      PARAMS ${CLANG_TEST_PARAMS} DXC_DXIL_DLL_PATH=${DXC_PATH}
+      DEPENDS ${CLANG_TEST_DEPS} ${name}
+      ARGS ${CLANG_TEST_EXTRA_ARGS}
+    )
 
-# Manually generate targets that we need to expose in visual studio builds.
+    # Hook into check-all
+    if (WIN32 AND TARGET check-all)
+      add_dependencies(check-all "check-clang-${name}")
+    endif()  
+  endif()
+endforeach()
+# -------------------------------------------------------------------------
 
 # The code below here _ONLY_ executes when building with Visual Studio or Xcode.
 if (NOT CMAKE_CONFIGURATION_TYPES)

tools/clang/test/LitDXILValidation/Environment.test

@@ -0,0 +1,3 @@
+# REQUIRES: dxc_dxil_dll_path
+# RUN: python -c "import os; print(os.environ['DXC_DXIL_DLL_PATH'])" | FileCheck %s
+# CHECK: dxil.dll

tools/clang/test/lit.cfg

@@ -14,6 +14,9 @@ import lit.util
 # name: The name of this test suite.
 config.name = 'Clang'
 
+print("PARAMS seen in top level config:", lit_config.params)
+
+
 # Tweak PATH for Win32
 if platform.system() == 'Windows':
     # Seek sane tools in directories and set to $PATH.
@@ -94,6 +97,12 @@ for name in possibly_dangerous_env_vars:
   if name in config.environment:
     del config.environment[name]
 
+dxc_dll_path = lit_config.params.get('DXC_DXIL_DLL_PATH', None)
+if dxc_dll_path and os.path.exists(dxc_dll_path):
+    lit_config.note("Setting DXC_DXIL_DLL_PATH environment variable")
+    config.environment.update({'DXC_DXIL_DLL_PATH' : dxc_dll_path})
+    config.available_features.add("dxc_dxil_dll_path")
+
 # Tweak the PATH to include the tools dir and the scripts dir.
 if clang_obj_root is not None:
     clang_tools_dir = getattr(config, 'clang_tools_dir', None)

tools/clang/unittests/HLSL/ValidationTest.cpp

@@ -34,7 +34,6 @@
 #include "dxc/Support/Global.h"
 
 #include "dxc/DXIL/DxilShaderModel.h"
-#include "dxc/Support/dxcapi.extval.h"
 #include "dxc/Test/DxcTestUtils.h"
 #include "dxc/Test/HlslTestUtils.h"
 
@@ -327,11 +326,12 @@ class ValidationTest : public ::testing::Test {
   TEST_METHOD(PSVContentValidationMS)
   TEST_METHOD(PSVContentValidationAS)
   TEST_METHOD(UnitTestExtValidationSupport)
+  TEST_METHOD(UnitTestValidationBackCompatibility)
   TEST_METHOD(WrongPSVSize)
   TEST_METHOD(WrongPSVSizeOnZeros)
   TEST_METHOD(WrongPSVVersion)
 
-  dxc::DxCompilerDllLoader m_dllSupport;
+  dxc::DxcDllExtValidationLoader m_dllSupport;
   VersionSupportInfo m_ver;
 
   void TestCheck(LPCWSTR name) {
@@ -4302,6 +4302,17 @@ TEST_F(ValidationTest, UnitTestExtValidationSupport) {
 }
 #endif
 
+// Building on the above test, this test uses the DxcDllExtValidationLoader
+// class to instantiate loader objects using previously released
+// dxcompiler.dll's. The environment will also be set up so that the previous
+// dxil.dll's will also be loaded (to be used for external validation).
+TEST_F(ValidationTest, UnitTestValidationBackCompatibility) {
+  dxc::DxcDllExtValidationLoader ExtSupport;
+  ExtSupport.Initialize();
+  std::string dllPath = ExtSupport.GetDxilDllPath();
+  VERIFY_IS_TRUE(dllPath.empty());
+}
+
 TEST_F(ValidationTest, ValidatePreviewBypassHash) {
   if (m_ver.SkipDxilVersion(1, ShaderModel::kHighestMinor))
     return;

tools/clang/unittests/HLSLExec/CMakeLists.txt

@@ -5,8 +5,6 @@ find_package(D3D12 REQUIRED) # Used for ExecutionTest.cpp.
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /bigobj")
 
-set(DXCSUPPORT_DIR "${CMAKE_SOURCE_DIR}/lib/DxcSupport")
-
 add_clang_library(ExecHLSLTests SHARED
   ExecutionTest.cpp
   ShaderOpTest.cpp

tools/clang/unittests/HLSLTestLib/DxcTestUtils.cpp

@@ -196,6 +196,20 @@ std::string DisassembleProgram(dxc::DxCompilerDllLoader &dllSupport,
   return BlobToUtf8(pDisassembly);
 }
 
+std::string DisassembleProgram(dxc::DxcDllExtValidationLoader &dllSupport,
+                               IDxcBlob *pProgram) {
+  CComPtr<IDxcCompiler> pCompiler;
+  CComPtr<IDxcBlobEncoding> pDisassembly;
+
+  if (!dllSupport.IsEnabled()) {
+    VERIFY_SUCCEEDED(dllSupport.Initialize());
+  }
+
+  VERIFY_SUCCEEDED(dllSupport.CreateInstance(CLSID_DxcCompiler, &pCompiler));
+  VERIFY_SUCCEEDED(pCompiler->Disassemble(pProgram, &pDisassembly));
+  return BlobToUtf8(pDisassembly);
+}
+
 void AssembleToContainer(dxc::DllLoader &dllSupport, IDxcBlob *pModule,
                          IDxcBlob **pContainer) {
   CComPtr<IDxcAssembler> pAssembler;