Integrate LLD 6.0.0+ for ELF and Mach-O targets

LLD 5.0.0+ would work too, but as there's a new lldCommon library for
LLD 6.0.0 (and no more lldConfig), simply require 6.0.0+ to keep the
CMake setup reasonably simple.

CMakeLists.txt

@@ -449,14 +449,20 @@ if(NOT DEFINED LDC_WITH_LLD)
         endif()
         unset(CMAKE_REQUIRED_FLAGS)
         unset(CMAKE_REQUIRED_INCLUDES)
+        # translate 1/0 to ON/OFF
+        if(LDC_WITH_LLD)
+            set(LDC_WITH_LLD ON)
+        else()
+            set(LDC_WITH_LLD OFF)
+        endif()
     else()
         set(LDC_WITH_LLD OFF)
     endif()
 endif()
 if(LDC_WITH_LLD)
-    message(STATUS "Building LDC with LLD support")
     append("-DLDC_WITH_LLD" LDC_CXXFLAGS)
 endif()
+message(STATUS "Building LDC with integrated LLD: ${LDC_WITH_LLD} (LDC_WITH_LLD=${LDC_WITH_LLD})")
 
 #
 # Enable building with riscv-llvm, for full RISC-V support.
@@ -560,21 +566,23 @@ add_custom_target(${LDMD_EXE} ALL DEPENDS ${LDMD_EXE_FULL})
 
 # Figure out how to link the main LDC executable, for which we need to take the
 # LLVM flags into account.
-set(LDC_LINKERFLAG_LIST "${SANITIZE_LDFLAGS};${LLVM_LIBRARIES};${LLVM_LDFLAGS}")
+set(LDC_LINKERFLAG_LIST ${SANITIZE_LDFLAGS} ${LLVM_LIBRARIES} ${LLVM_LDFLAGS})
 if(LDC_WITH_LLD)
+    # ELF and Mach-O formats supported since LLD 6.0.0, otherwise just Windows COFF
     if(NOT (LDC_LLVM_VER LESS 600))
         if(MSVC)
-            list(APPEND LDC_LINKERFLAG_LIST lldCOFF.lib lldCommon.lib lldCore.lib lldDriver.lib)
-        elseif(APPLE)
-            set(LDC_LINKERFLAG_LIST "-llldCOFF;-llldCommon;-llldCore;-llldDriver;${LDC_LINKERFLAG_LIST};-lxml2")
+            list(APPEND LDC_LINKERFLAG_LIST lldDriver.lib lldCOFF.lib lldELF.lib lldMachO.lib lldYAML.lib lldReaderWriter.lib lldCommon.lib lldCore.lib)
         else()
-            set(LDC_LINKERFLAG_LIST "-llldCOFF;-llldCommon;-llldCore;-llldDriver;${LDC_LINKERFLAG_LIST}")
+            set(LDC_LINKERFLAG_LIST -llldDriver -llldCOFF -llldELF -llldMachO -llldYAML -llldReaderWriter -llldCommon -llldCore ${LDC_LINKERFLAG_LIST})
+        endif()
+        if(APPLE) # bug, should be fixed in LLVM 6.0.1
+            list(APPEND LDC_LINKERFLAG_LIST -lxml2)
         endif()
     else()
         if(MSVC)
             list(APPEND LDC_LINKERFLAG_LIST lldCOFF.lib lldCore.lib lldDriver.lib)
         else()
-            set(LDC_LINKERFLAG_LIST "-llldCOFF;-llldCore;-llldDriver;${LDC_LINKERFLAG_LIST}")
+            set(LDC_LINKERFLAG_LIST -llldCOFF -llldCore -llldDriver ${LDC_LINKERFLAG_LIST})
         endif()
     endif()
 endif()
@@ -593,7 +601,7 @@ if(LDC_ENABLE_PLUGINS)
         set(LDC_LINKERFLAG_LIST "${LDC_LINKERFLAG_LIST};-Wl,--export-dynamic")
     endif()
 endif()
-message(STATUS "Building LDC with plugin support ${LDC_ENABLE_PLUGINS} (LDC_ENABLE_PLUGINS=${LDC_ENABLE_PLUGINS})")
+message(STATUS "Building LDC with plugin support: ${LDC_ENABLE_PLUGINS} (LDC_ENABLE_PLUGINS=${LDC_ENABLE_PLUGINS})")
 
 set(LDC_LINK_MANUALLY OFF)
 if(UNIX AND (CMAKE_COMPILER_IS_GNUCXX OR (${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")))

driver/linker-gcc.cpp

@@ -23,6 +23,10 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 
+#if LDC_WITH_LLD && LDC_LLVM_VER >= 600
+#include "lld/Common/Driver.h"
+#endif
+
 //////////////////////////////////////////////////////////////////////////////
 
 static llvm::cl::opt<std::string>
@@ -594,7 +598,7 @@ void ArgsBuilder::addTargetFlags() {
 }
 
 //////////////////////////////////////////////////////////////////////////////
-// (Yet unused) specialization for plain ld.
+// Specialization for plain ld.
 
 class LdArgsBuilder : public ArgsBuilder {
   void addSanitizers(const llvm::Triple &triple) override {}
@@ -628,6 +632,30 @@ class LdArgsBuilder : public ArgsBuilder {
 
 int linkObjToBinaryGcc(llvm::StringRef outputPath, bool useInternalLinker,
                        llvm::cl::boolOrDefault fullyStaticFlag) {
+#if LDC_WITH_LLD && LDC_LLVM_VER >= 600
+  if (useInternalLinker) {
+    LdArgsBuilder argsBuilder;
+    argsBuilder.build(outputPath, fullyStaticFlag);
+
+    const auto fullArgs =
+        getFullArgs("ld.lld", argsBuilder.args, global.params.verbose);
+
+    bool success = false;
+    if (global.params.targetTriple->isOSBinFormatELF()) {
+      success = lld::elf::link(fullArgs, /*CanExitEarly*/ false);
+    } else if (global.params.targetTriple->isOSBinFormatMachO()) {
+      success = lld::mach_o::link(fullArgs);
+    } else {
+      error(Loc(), "unknown target binary format for internal linking");
+    }
+
+    if (!success)
+      error(Loc(), "linking with LLD failed");
+
+    return success ? 0 : 1;
+  }
+#endif
+
   // find gcc for linking
   const std::string tool = getGcc();
 

runtime/CMakeLists.txt

@@ -255,9 +255,9 @@ endif()
 # The installed config file doesn't use SHARED_LIBS_RPATH.
 if(NOT ${BUILD_SHARED_LIBS} STREQUAL "OFF")
     if(MULTILIB AND NOT "${TARGET_SYSTEM}" MATCHES "APPLE")
-        set(SHARED_LIBS_RPATH "\n        \"-L-Wl,-rpath,${CMAKE_BINARY_DIR}/lib${LIB_SUFFIX}:${CMAKE_BINARY_DIR}/lib${MULTILIB_SUFFIX}\",")
+        set(SHARED_LIBS_RPATH "\n        \"-L-rpath\", \"-L${CMAKE_BINARY_DIR}/lib${LIB_SUFFIX}:${CMAKE_BINARY_DIR}/lib${MULTILIB_SUFFIX}\",")
     else()
-        set(SHARED_LIBS_RPATH "\n        \"-L-Wl,-rpath,${CMAKE_BINARY_DIR}/lib${LIB_SUFFIX}\",")
+        set(SHARED_LIBS_RPATH "\n        \"-L-rpath\", \"-L${CMAKE_BINARY_DIR}/lib${LIB_SUFFIX}\",")
     endif()
 endif()