[cmake] Remove the LLDB versions of the exception-controlling variables

[labath]

Summary

One can still use the LLVM variables to control this: LLVM_ENABLE_EH, LLVM_ENABLE_RTTI. It's not
clear to me why one would want to control these at lldb level and it's generally not even a good
idea to compile parts of the same binary with different values of these flags.

[labath]

Zachary, Todd, you added these in D3929. I know it's a long time, but do you recall what was the original motivation for that?

In light of the issue in D20671, I've experimenting with compiling lldb with exceptions enabled, and this code here is interfering with the standard llvm logic for enabling them (LLVM_ENABLE_EH). Enabling this should not make any difference in the common case, as llvm already adds one set of exception-disabling flags if you don't specify the flag I mentioned (llvm/cmake/modules/AddLLVM.cmake).

So, unless we know of a concrete use case where this is needed, I think we should remove it.

[tfiala]

Having a look now. I don't recall the context yet.

[labath]

In D20673#440660, @labath wrote:

Enabling this should not make any difference in the common case, as llvm already adds one set of exception-disabling flags if you don't specify the flag I mentioned (llvm/cmake/modules/AddLLVM.cmake).

(And by "Enabling" I mean "Removing" :P )

[tfiala]

This looks fine to me. ( D20671 also looked fine, looks like I missed looking at that yesterday).

Since Zachary initially wanted this on Windows, I suspect he needs to verify that he can still achieve the same result.

[tfiala]

In D20673#440967, @labath wrote:

In D20673#440660, @labath wrote:

Enabling this should not make any difference in the common case, as llvm already adds one set of exception-disabling flags if you don't specify the flag I mentioned (llvm/cmake/modules/AddLLVM.cmake).

(And by "Enabling" I mean "Removing" :P )

;-)

[zturner]

Don't think this is needed anymore, lgtm

lldb/trunk/cmake/modules/LLDBConfig.cmake

 if (HAVE_LIBPTHREAD)
   list(APPEND system_libs pthread)
 endif(HAVE_LIBPTHREAD)
 
 if (HAVE_LIBDL)
   list(APPEND system_libs ${CMAKE_DL_LIBS})
 endif()
 
-if(LLDB_REQUIRES_EH)
-  set(LLDB_REQUIRES_RTTI ON)
-else()
-  if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
-    set(LLDB_COMPILE_FLAGS "${LLDB_COMPILE_FLAGS} -fno-exceptions")
-  elseif(MSVC)
-    add_definitions( -D_HAS_EXCEPTIONS=0 )
-    set(LLDB_COMPILE_FLAGS "${LLDB_COMPILE_FLAGS} /EHs-c-")
-  endif()
-endif()
-
-# Disable RTTI by default
-if(NOT LLDB_REQUIRES_RTTI)
-  if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
-    set(LLDB_COMPILE_FLAGS "${LLDB_COMPILE_FLAGS} -fno-rtti")
-  elseif(MSVC)
-    set(LLDB_COMPILE_FLAGS "${LLDB_COMPILE_FLAGS} /GR-")
-  endif()
-endif()
-
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LLDB_COMPILE_FLAGS}")
-
 if (CMAKE_SYSTEM_NAME MATCHES "Linux")
     # Check for syscall used by lldb-server on linux.
     # If these are not found, it will fall back to ptrace (slow) for memory reads.
     check_cxx_source_compiles("
         #include <sys/uio.h>
         int main() { process_vm_readv(0, nullptr, 0, nullptr, 0, 0); return 0; }"
         HAVE_PROCESS_VM_READV)