Driver: introduce new -libc option for Windows

CMakeLists.txt

@@ -173,6 +173,20 @@ set(SWIFT_STDLIB_BUILD_TYPE "${CMAKE_BUILD_TYPE}" CACHE STRING
     "Build type for the Swift standard library and SDK overlays [Debug, RelWithDebInfo, Release, MinSizeRel]")
 set_property(CACHE SWIFT_STDLIB_BUILD_TYPE PROPERTY
     STRINGS "Debug" "RelWithDebInfo" "Release" "MinSizeRel")
+# Allow the user to specify the standard library CMAKE_MSVC_RUNTIME_LIBRARY
+# value.  The following values are valid:
+#   - MultiThreaded (/MT)
+#   - MultiThreadedDebug (/MTd)
+#   - MultiThreadedDLL (/MD)
+#   - MultiThreadedDebugDLL (/MDd)
+if(CMAKE_BUILD_TYPE STREQUAL Debug)
+  set(SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY_default MultiThreadedDebugDLL)
+else()
+  set(SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY_default MultiThreadedDLL)
+endif()
+set(SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY
+  ${SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY_default}
+  CACHE STRING "MSVC Runtime Library for the standard library")
 
 is_build_type_optimized("${SWIFT_STDLIB_BUILD_TYPE}" swift_optimized)
 if(swift_optimized)

cmake/modules/AddSwift.cmake

@@ -400,12 +400,6 @@ function(_add_variant_swift_compile_flags
     list(APPEND result "-D" "SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS")
   endif()
 
-  if(sdk STREQUAL WINDOWS)
-    list(APPEND result "-Xcc" "-D_MT")
-    # TODO(compnerd) handle /MT /MTd
-    list(APPEND result "-Xcc" "-D_DLL")
-  endif()
-
   set("${result_var_name}" "${result}" PARENT_SCOPE)
 endfunction()
 
@@ -873,13 +867,8 @@ function(_add_swift_library_single target name)
     if("${SWIFTLIB_SINGLE_ARCHITECTURE}" MATCHES arm)
       list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS -Xcc;-D_ARM_WINAPI_PARTITION_DESKTOP_SDK_AVAILABLE)
     endif()
-    list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS -Xfrontend;-autolink-library;-Xfrontend;oldnames)
-    # TODO(compnerd) handle /MT and /MTd
-    if(CMAKE_BUILD_TYPE MATCHES Debug)
-      list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS -Xfrontend;-autolink-library;-Xfrontend;msvcrtd)
-    else()
-      list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS -Xfrontend;-autolink-library;-Xfrontend;msvcrt)
-    endif()
+    list(APPEND SWIFTLIB_SINGLE_SWIFT_COMPILE_FLAGS
+      -libc;${SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY})
   endif()
 
   # FIXME: don't actually depend on the libraries in SWIFTLIB_SINGLE_LINK_LIBRARIES,

include/swift/Driver/Driver.h

@@ -87,9 +87,18 @@ class OutputInfo {
     Immediate,
   };
 
+  enum class MSVCRuntime {
+    MultiThreaded,
+    MultiThreadedDebug,
+    MultiThreadedDLL,
+    MultiThreadedDebugDLL,
+  };
+
   /// The mode in which the driver should invoke the frontend.
   Mode CompilerMode = Mode::StandardCompile;
 
+  Optional<MSVCRuntime> RuntimeVariant = llvm::None;
+
   /// The output type which should be used for compile actions.
   file_types::ID CompilerOutputType = file_types::ID::TY_INVALID;
 

include/swift/Option/Options.td

@@ -455,6 +455,8 @@ def enable_app_extension : Flag<["-"], "application-extension">,
   Flags<[FrontendOption, NoInteractiveOption]>,
   HelpText<"Restrict code to those available for App Extensions">;
 
+def libc : Separate<["-"], "libc">, HelpText<"libc runtime library to use">;
+
 // Linker options
 
 def linker_option_Group : OptionGroup<"<linker-specific options>">;

lib/Driver/Driver.cpp

@@ -1650,6 +1650,31 @@ void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
 
   }
 
+  if (TC.getTriple().isOSWindows()) {
+    if (const Arg *A = Args.getLastArg(options::OPT_libc)) {
+      OI.RuntimeVariant =
+          llvm::StringSwitch<Optional<OutputInfo::MSVCRuntime>>(A->getValue())
+              .Cases("MD", "MultiThreadedDLL", "shared-ucrt",
+                     OutputInfo::MSVCRuntime::MultiThreadedDLL)
+              .Cases("MDd", "MultiThreadedDebugDLL", "shared-debug-ucrt",
+                     OutputInfo::MSVCRuntime::MultiThreadedDebugDLL)
+              .Cases("MT", "MultiThreaded", "static-ucrt",
+                     OutputInfo::MSVCRuntime::MultiThreaded)
+              .Cases("MTd", "MultiThreadedDebug", "static-debug-ucrt",
+                     OutputInfo::MSVCRuntime::MultiThreadedDebug)
+              .Default(llvm::None);
+      if (!OI.RuntimeVariant)
+        Diags.diagnose({}, diag::error_invalid_arg_value, A->getSpelling(),
+                       A->getValue());
+    } else {
+      // NOTE: default to `/MD`.  This is different from `cl`'s default
+      // behaviour of `/MT` on the command line, however, Visual Studio 2015 and
+      // newer will default `/MD` as well.  Furthermore, this is far more useful
+      // of a mode since the `/MT` mode requires that everything is statically
+      // linked.
+      OI.RuntimeVariant = OutputInfo::MSVCRuntime::MultiThreadedDLL;
+    }
+  }
 }
 
 OutputInfo::Mode

lib/Driver/ToolChains.cpp

@@ -261,6 +261,47 @@ static void addCommonFrontendArgs(const ToolChain &TC, const OutputInfo &OI,
     arguments.push_back("-color-diagnostics");
 }
 
+static void addRuntimeLibraryFlags(const OutputInfo &OI,
+                                   ArgStringList &Arguments) {
+  if (!OI.RuntimeVariant)
+    return;
+
+  const OutputInfo::MSVCRuntime RT = OI.RuntimeVariant.getValue();
+
+  Arguments.push_back("-autolink-library");
+  Arguments.push_back("oldnames");
+
+  Arguments.push_back("-autolink-library");
+  switch (RT) {
+  default: llvm_unreachable("invalid MSVC runtime library");
+  case OutputInfo::MSVCRuntime::MultiThreaded:
+    Arguments.push_back("libcmt");
+    break;
+
+  case OutputInfo::MSVCRuntime::MultiThreadedDebug:
+    Arguments.push_back("libcmtd");
+    break;
+
+  case OutputInfo::MSVCRuntime::MultiThreadedDLL:
+    Arguments.push_back("msvcrt");
+    break;
+
+  case OutputInfo::MSVCRuntime::MultiThreadedDebugDLL:
+    Arguments.push_back("msvcrtd");
+    break;
+  }
+
+  // NOTE(compnerd) we do not support /ML and /MLd
+  Arguments.push_back("-Xcc");
+  Arguments.push_back("-D_MT");
+
+  if (RT == OutputInfo::MSVCRuntime::MultiThreadedDLL ||
+      RT == OutputInfo::MSVCRuntime::MultiThreadedDebugDLL) {
+    Arguments.push_back("-Xcc");
+    Arguments.push_back("-D_DLL");
+  }
+}
+
 ToolChain::InvocationInfo
 ToolChain::constructInvocation(const CompileJobAction &job,
                                const JobContext &context) const {
@@ -301,6 +342,7 @@ ToolChain::constructInvocation(const CompileJobAction &job,
 
   addCommonFrontendArgs(*this, context.OI, context.Output, context.Args,
                         Arguments);
+  addRuntimeLibraryFlags(context.OI, Arguments);
 
   // Pass along an -import-objc-header arg, replacing the argument with the name
   // of any input PCH to the current action if one is present.
@@ -614,6 +656,8 @@ ToolChain::constructInvocation(const InterpretJobAction &job,
 
   addCommonFrontendArgs(*this, context.OI, context.Output, context.Args,
                         Arguments);
+  addRuntimeLibraryFlags(context.OI, Arguments);
+
   context.Args.AddLastArg(Arguments, options::OPT_import_objc_header);
 
   context.Args.AddLastArg(Arguments, options::OPT_parse_sil);
@@ -825,6 +869,8 @@ ToolChain::constructInvocation(const MergeModuleJobAction &job,
 
   addCommonFrontendArgs(*this, context.OI, context.Output, context.Args,
                         Arguments);
+  addRuntimeLibraryFlags(context.OI, Arguments);
+
   addOutputsOfType(Arguments, context.Output, context.Args,
                    file_types::TY_SwiftModuleDocFile, "-emit-module-doc-path");
   addOutputsOfType(Arguments, context.Output, context.Args,
@@ -908,8 +954,11 @@ ToolChain::constructInvocation(const REPLJobAction &job,
   ArgStringList FrontendArgs;
   for (auto &s : getDriver().getSwiftProgramArgs())
     FrontendArgs.push_back(s.c_str());
+
   addCommonFrontendArgs(*this, context.OI, context.Output, context.Args,
                         FrontendArgs);
+  addRuntimeLibraryFlags(context.OI, FrontendArgs);
+
   context.Args.AddLastArg(FrontendArgs, options::OPT_import_objc_header);
   context.Args.AddAllArgs(FrontendArgs, options::OPT_l, options::OPT_framework,
                           options::OPT_L);
@@ -994,6 +1043,8 @@ ToolChain::constructInvocation(const GeneratePCHJobAction &job,
 
   addCommonFrontendArgs(*this, context.OI, context.Output, context.Args,
                         Arguments);
+  addRuntimeLibraryFlags(context.OI, Arguments);
+
   addOutputsOfType(Arguments, context.Output, context.Args,
                    file_types::TY_SerializedDiagnostics,
                    "-serialize-diagnostics-path");

lib/Driver/WindowsToolChains.cpp

@@ -100,6 +100,12 @@ toolchains::Windows::constructInvocation(const LinkJobAction &job,
     Arguments.push_back(context.Args.MakeArgString(Target));
   }
 
+  // Rely on `-libc` to correctly identify the MSVC Runtime Library.  We use
+  // `-nostartfiles` as that limits the difference to just the
+  // `-defaultlib:libcmt` which is passed unconditionally with the `clang++`
+  // driver rather than the `clang-cl` driver.
+  Arguments.push_back("-nostartfiles");
+
   SmallString<128> SharedRuntimeLibPath;
   getRuntimeLibraryPath(SharedRuntimeLibPath, context.Args,
                         /*Shared=*/true);

test/DebugInfo/debug_prefix_map.swift

@@ -9,4 +9,4 @@ func square(_ n: Int) -> Int {
 }
 
 // CHECK: !DIFile(filename: "/var/empty/debug_prefix_map.swift"
-// CHECK: !DIModule(scope: null, name: "Globals", includePath: "/var/empty{{(/|\\5C)}}Globals.swiftmodule"
+// CHECK: !DIModule(scope: null, name: "Globals", {{.*}}includePath: "/var/empty{{(/|\\5C)}}Globals.swiftmodule"

test/Driver/windows-libc-options.swift

@@ -0,0 +1,25 @@
+// -- check that invalid values are flagged
+// RUN: not %swiftc_driver -target x86_64-unknown-windows-msvc -libc MLd -c %s -### 2>&1 | %FileCheck %s -check-prefix CHECK-INVALID
+// CHECK-INVALID: error: invalid value 'MLd' in '-libc'
+
+// -- check that cross-compilation still succeeds
+// RUN: %swiftc_driver -target x86_64-unknown-linux-gnu -c %s -###
+
+// -- check flags for /MD
+// RUN: %swiftc_driver -target x86_64-unknown-windows-msvc -libc MD -c %s -### 2>&1 | %FileCheck %s -check-prefix CHECK-MD
+// CHECK-MD: -autolink-library oldnames -autolink-library msvcrt -Xcc -D_MT -Xcc -D_DLL
+
+// -- check flags for /MDd
+// RUN: %swiftc_driver -target x86_64-unknown-windows-msvc -libc MDd -c %s -### 2>&1 | %FileCheck %s -check-prefix CHECK-MDd
+// CHECK-MDd: -autolink-library oldnames -autolink-library msvcrtd -Xcc -D_MT -Xcc -D_DLL
+
+// -- check flags for /MT
+// RUN: %swiftc_driver -target x86_64-unknown-windows-msvc -libc MT -c %s -### 2>&1 | %FileCheck %s -check-prefix CHECK-MT
+// CHECK-MT: -autolink-library oldnames -autolink-library libcmt -Xcc -D_MT
+// CHECK-MT-NOT: -D_DLL
+
+// -- check flags for /MTd
+// RUN: %swiftc_driver -target x86_64-unknown-windows-msvc -libc MTd -c %s -### 2>&1 | %FileCheck %s -check-prefix CHECK-MTd
+// CHECK-MTd: -autolink-library oldnames -autolink-library libcmtd -Xcc -D_MT
+// CHECK-MTd-NOT: -D_DLL
+

test/lit.cfg

@@ -374,8 +374,15 @@ config.substitutions.append( ('%mcp_opt', mcp_opt) )
 config.substitutions.append( ('%swift_driver_plain', "%r" % config.swift) )
 config.substitutions.append( ('%swiftc_driver_plain', "%r" % config.swiftc) )
 if kIsWindows:
-    config.substitutions.append( ('%swift_driver', "%r %s %s %s" % (config.swift, mcp_opt, config.swift_test_options, config.swift_driver_test_options)) )
-    config.substitutions.append( ('%swiftc_driver', "%r %s %s %s" % (config.swiftc, mcp_opt, config.swift_test_options, config.swift_driver_test_options)) )
+    config.substitutions.append( ('%swift_driver',
+                                  "%r %s %s %s -libc %s" % (config.swift, mcp_opt,
+                                                            config.swift_test_options,
+                                                            config.swift_driver_test_options,
+                                                            config.swift_stdlib_msvc_runtime)) )
+    config.substitutions.append( ('%swiftc_driver',
+                                  "%r %s %s %s" % (config.swiftc, mcp_opt,
+                                                   config.swift_test_options,
+                                                   config.swift_driver_test_options)) )
 else:
     config.substitutions.append( ('%swift_driver', "env SDKROOT= %r %s %s %s" % (config.swift, mcp_opt, config.swift_test_options, config.swift_driver_test_options)) )
     config.substitutions.append( ('%swiftc_driver', "env SDKROOT= %r %s %s %s" % (config.swiftc, mcp_opt, config.swift_test_options, config.swift_driver_test_options)) )
@@ -870,10 +877,11 @@ elif run_os in ['windows-msvc']:
     config.target_runtime = 'native'
 
     config.target_build_swift =                                                  \
-            ('%r -target %s %s %s %s %s -Xlinker -nodefaultlib:libcmt' %         \
+            ('%r -target %s %s %s %s %s -libc %s' %                              \
                     (config.swiftc, config.variant_triple, resource_dir_opt,     \
                      config.swift_test_options, config.swift_driver_test_options,\
-                     swift_execution_tests_extra_flags))
+                     swift_execution_tests_extra_flags,                          \
+                     config.swift_stdlib_msvc_runtime))
 
     config.target_run = ''
 

test/lit.site.cfg.in

@@ -27,6 +27,18 @@ config.variant_triple = "@VARIANT_TRIPLE@"
 config.variant_sdk = "@VARIANT_SDK@"
 config.variant_suffix = "@VARIANT_SUFFIX@"
 config.swiftlib_dir = "@LIT_SWIFTLIB_DIR@"
+config.swift_stdlib_msvc_runtime = None
+if "@SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY@" == "MultiThreaded":
+    config.swift_stdlib_msvc_runtime = 'MT'
+elif "@SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY@" == "MultiThreadedDebug":
+    config.swift_stdlib_msvc_runtime = 'MTd'
+elif "@SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY@" == "MultiThreadedDLL":
+    config.swift_stdlib_msvc_runtime = 'MD'
+elif "@SWIFT_STDLIB_MSVC_RUNTIME_LIBRARY@" == "MultiThreadedDebugDLL":
+    config.swift_stdlib_msvc_runtime = 'MDd'
+else:
+    assert(False)
+
 config.swift_test_results_dir = \
     lit_config.params.get("swift_test_results_dir", "@SWIFT_TEST_RESULTS_DIR@")
 config.darwin_xcrun_toolchain = "@SWIFT_DARWIN_XCRUN_TOOLCHAIN@"