Use clang instead if llvm-lto for darwin-based targets (#2974)

* Use LLVM C API for optimizations
* Use Clang for bitcode compilation
* Test bitcode embedding

llvmCoverageMappingC/build.gradle

@@ -30,6 +30,15 @@ model {
           if (!project.parent.convention.plugins.platformInfo.isWindows())
              cppCompiler.args "-fPIC"
           cppCompiler.args "--std=c++11", "-I${llvmDir}/include", "-I${projectDir}/src/main/include"
+          if (isMac()) {
+            cppCompiler.args "-DKONAN_MACOS=1"
+          } else if (isWindows()) {
+            cppCompiler.args "-DKONAN_WINDOWS=1"
+          } else if (isLinux()) {
+            cppCompiler.args "-DKONAN_LINUX=1"
+          } else {
+            throw new Error("Unsupported host OS.")
+          }
           linker.args "-L${llvmDir}/lib", "-lLLVMCore", "-lLLVMSupport"
         }
         binaries.withType(SharedLibraryBinarySpec) { binary ->

llvmCoverageMappingC/src/main/cpp/CoverageMappingC.cpp

@@ -227,4 +227,22 @@ void LLVMAddInstrProfPass(LLVMPassManagerRef passManagerRef, const char* outputF
 LLVMTargetLibraryInfoRef LLVMGetTargetLibraryInfo(LLVMModuleRef moduleRef) {
     auto* libraryInfo = new TargetLibraryInfoImpl(Triple(unwrap(moduleRef)->getTargetTriple()));
     return llvm::wrap(libraryInfo);
+}
+
+void LLVMKotlinInitializeTargets() {
+#define INIT_LLVM_TARGET(TargetName) \
+    LLVMInitialize##TargetName##TargetInfo();\
+    LLVMInitialize##TargetName##Target();\
+    LLVMInitialize##TargetName##TargetMC();
+#if KONAN_MACOS
+    INIT_LLVM_TARGET(AArch64)
+    INIT_LLVM_TARGET(ARM)
+    INIT_LLVM_TARGET(Mips)
+    INIT_LLVM_TARGET(X86)
+    INIT_LLVM_TARGET(WebAssembly)
+#elif KONAN_LINUX
+#elif KONAN_WINDOWS
+#endif
+
+#undef INIT_LLVM_TARGET
 }

llvmCoverageMappingC/src/main/include/CoverageMappingC.h

@@ -74,8 +74,9 @@ void LLVMAddInstrProfPass(LLVMPassManagerRef passManagerRef, const char* outputF
 
 LLVMTargetLibraryInfoRef LLVMGetTargetLibraryInfo(LLVMModuleRef moduleRef);
 
+void LLVMKotlinInitializeTargets();
+
 # ifdef __cplusplus
 }
-
 # endif
 #endif