llvm-config: Add --has-rtti option

[• tstellarAMD]

Summary

This prints NO if LLVM was built with -fno-rtti or an equivalent flag
and YES otherwise. The reasons to add -has-rtti rather than adding -fno-rtti
to --cxxflags are:

1. Building LLVM with -fno-rtti does not always mean that client

applications need this flag.

2. Some compilers have a different flag for disabling rtti, and the

compiler being used to build LLVM may not be the compiler being used to
build the application.

[beanz]

Tom,

What about -fno-exceptions? Does we need to handle that flag similarly? There is a thread on llvm-commits today that proposed an alternate solution that covers that case too.

I cc'd you on the thread on llvm-commits, can you please review and provide feedback.

Thanks,
-Chris

[• tstellarAMD]

In D11849#224127, @beanz wrote:

Tom,

What about -fno-exceptions? Does we need to handle that flag similarly? There is a thread on llvm-commits today that proposed an alternate solution that covers that case too.

I cc'd you on the thread on llvm-commits, can you please review and provide feedback.

Thanks,
-Chris

In D11849#224127, @beanz wrote:

Tom,

What about -fno-exceptions? Does we need to handle that flag similarly? There is a thread on llvm-commits today that proposed an alternate solution that covers that case too.

I don't think that compiling LLVM with -fno-exceptions requires library users to use the same, which would mean we don't need a flag for it. However, we should find someone who knows C++ better than I to confirm or refute this.

[jroelofs]

In D11849#224191, @tstellarAMD wrote:

In D11849#224127, @beanz wrote:

Tom,

What about -fno-exceptions? Does we need to handle that flag similarly? There is a thread on llvm-commits today that proposed an alternate solution that covers that case too.

I don't think that compiling LLVM with -fno-exceptions requires library users to use the same, which would mean we don't need a flag for it. However, we should find someone who knows C++ better than I to confirm or refute this.

Correct. -fno-exceptions code can link against -fexceptions code. You'll only see issues if you attempt to throw across the boundary (for example in a callback).

[jroelofs]

LGTM

cmake/modules/AddLLVM.cmake

else()
     if (CLANG_CL)
       # FIXME: Remove this once clang-cl supports SEH
       list(APPEND LLVM_COMPILE_DEFINITIONS "GTEST_HAS_SEH=0")
     endif()
   endif()
 
   # LLVM_REQUIRES_RTTI is an internal flag that individual
   # targets can use to force RTTI
+  set(LLVM_CONFIG_HAS_RTTI YES CACHE INTERNAL "")
   if(NOT (LLVM_REQUIRES_RTTI OR LLVM_ENABLE_RTTI))
+    set(LLVM_CONFIG_HAS_RTTI NO CACHE INTERNAL "")
     list(APPEND LLVM_COMPILE_DEFINITIONS GTEST_HAS_RTTI=0)
     if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
       list(APPEND LLVM_COMPILE_FLAGS "-fno-rtti")
     elseif (MSVC)
       list(APPEND LLVM_COMPILE_FLAGS "/GR-")
     endif ()
   endif()
 

tools/llvm-config/BuildVariables.inc.in

 #define LLVM_CFLAGS "@LLVM_CFLAGS@"
 #define LLVM_LDFLAGS "@LLVM_LDFLAGS@"
 #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
 #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
 #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
 #define LLVM_TARGETS_BUILT "@LLVM_TARGETS_BUILT@"
 #define LLVM_SYSTEM_LIBS "@LLVM_SYSTEM_LIBS@"
 #define LLVM_BUILD_SYSTEM "@LLVM_BUILD_SYSTEM@"
+#define LLVM_HAS_RTTI "@LLVM_HAS_RTTI@"

tools/llvm-config/CMakeLists.txt

 
 # Use configure_file to create BuildVariables.inc.
 set(LLVM_SRC_ROOT ${LLVM_MAIN_SRC_DIR})
 set(LLVM_OBJ_ROOT ${LLVM_BINARY_DIR})
 set(LLVM_CPPFLAGS "${CMAKE_CPP_FLAGS} ${CMAKE_CPP_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
 set(LLVM_CFLAGS "${CMAKE_C_FLAGS} ${CMAKE_C_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
 set(LLVM_CXXFLAGS "${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
 set(LLVM_BUILD_SYSTEM cmake)
+set(LLVM_HAS_RTTI ${LLVM_CONFIG_HAS_RTTI})
 
 # Use the C++ link flags, since they should be a superset of C link flags.
 set(LLVM_LDFLAGS "${CMAKE_CXX_LINK_FLAGS}")
 set(LLVM_BUILDMODE ${CMAKE_BUILD_TYPE})
 set(LLVM_SYSTEM_LIBS ${SYSTEM_LIBS})
 string(REPLACE ";" " " LLVM_TARGETS_BUILT "${LLVM_TARGETS_TO_BUILD}")
 configure_file(${BUILDVARIABLES_SRCPATH} ${BUILDVARIABLES_OBJPATH} @ONLY)
 

tools/llvm-config/Makefile

 # Override LIBS with TARGET's LIBS for cross compilation.
 # FIXME: Host's llvm-config is not generated. It's for target's.
 ifneq ($(TARGET_LIBS), )
   LLVM_SYSTEM_LIBS := $(TARGET_LIBS)
 else
   LLVM_SYSTEM_LIBS := $(LIBS)
 endif
 
+ifneq ($(REQUIRES_RTTI), 1)
+  LLVM_HAS_RTTI := NO
+else
+  LLVM_HAS_RTTI := YES
+endif
+
 # This is blank for now.  We need to be careful about adding stuff here:
 # LDFLAGS tend not to be portable, and we don't currently require the
 # user to use libtool when linking against LLVM.
 SUB_LDFLAGS :=
 
 $(ObjDir)/BuildVariables.inc: $(BUILDVARIABLES_SRCPATH) Makefile $(ObjDir)/.dir
   $(Echo) "Building llvm-config BuildVariables.inc file."
   $(Verb) $(ECHO) 's/@LLVM_SRC_ROOT@/$(subst /,\/,$(LLVM_SRC_ROOT))/' \
$(ObjDir)/BuildVariables.inc: $(BUILDVARIABLES_SRCPATH) Makefile $(ObjDir)/.dir
   $(Verb) $(ECHO) 's/@LLVM_LIBDIR_SUFFIX@//' \
     >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_SYSTEM_LIBS@/$(subst /,\/,$(LLVM_SYSTEM_LIBS))/' \
     >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_TARGETS_BUILT@/$(subst /,\/,$(TARGETS_TO_BUILD))/' \
     >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_BUILD_SYSTEM@/autoconf/' \
     >> temp.sed
+  $(Verb) $(ECHO) 's/@LLVM_HAS_RTTI@/$(LLVM_HAS_RTTI)/' \
+    >> temp.sed
   $(Verb) $(SED) -f temp.sed < $< > $@
   $(Verb) $(RM) temp.sed
 
 # When cross-compiling, install a version of llvm-config that runs on the host.
 ifeq ($(LLVM_CROSS_COMPILING),1)
 install:: $(DESTDIR)$(PROJ_bindir)
   $(Echo) Installing llvm-config-host
   $(Verb) $(ProgInstall) $(BuildLLVMToolDir)/llvm-config \
     $(DESTDIR)$(PROJ_bindir)/$(program_prefix)llvm-config-host
 endif

tools/llvm-config/llvm-config.cpp

Options:\n\
   --libnames        Bare library names for in-tree builds.\n\
   --libfiles        Fully qualified library filenames for makefile depends.\n\
   --components      List of all possible components.\n\
   --targets-built   List of all targets currently built.\n\
   --host-target     Target triple used to configure LLVM.\n\
   --build-mode      Print build mode of LLVM tree (e.g. Debug or Release).\n\
   --assertion-mode  Print assertion mode of LLVM tree (ON or OFF).\n\
   --build-system    Print the build system used to build LLVM (autoconf or cmake).\n\
+  --has-rtti        Print whether or not LLVM was built with rtti (YES or NO).\n\
 Typical components:\n\
   all               All LLVM libraries (default).\n\
   engine            Either a native JIT or a bitcode interpreter.\n";
   exit(1);
 }
 
 /// \brief Compute the path to the main executable.
 std::string GetExecutablePath(const char *Argv0) {
if (Arg.startswith("-")) {
       } else if (Arg == "--assertion-mode") {
 #if defined(NDEBUG)
         OS << "OFF\n";
 #else
         OS << "ON\n";
 #endif
       } else if (Arg == "--build-system") {
         OS << LLVM_BUILD_SYSTEM << '\n';
+      } else if (Arg == "--has-rtti") {
+        OS << LLVM_HAS_RTTI << '\n';
       } else if (Arg == "--obj-root") {
         OS << ActivePrefix << '\n';
       } else if (Arg == "--src-root") {
         OS << LLVM_SRC_ROOT << '\n';
       } else {
         usage();
       }
     } else {