[llvm] r186499 - Tweak the cmake interaction between CMAKE_BUILD_TYPE and LLVM_ENABLE_ASSERTIONS.

[Tilmann Scheller]

IMHO we should make an unspecified CMAKE_BUILD_TYPE just default to Debug+Asserts (this would also increase consistency with the Makefile build).

I ran into a similar issue yesterday, I was wondering why an assert wouldn’t trigger. Looking at the disassembly I realized that the code for the assert was actually not there even though I was building with CMAKE_BUILD_TYPE=Debug. How could that happen?

Turns out when I did the initial configure of my build directory I forgot to set CMAKE_BUILD_TYPE, so once I realized I couldn’t debug my binary I did a CMAKE_BUILD_TYPE=Debug. After that debugging works fine again, however asserts are still turned off!

Regards,

Tilmann

On Sep 20, 2013, at 4:49 AM, Richard Smith <richard at metafoo.co.uk> wrote:

> On Wed, Jul 17, 2013 at 2:34 AM, Duncan Sands <baldrick at free.fr> wrote:
> Author: baldrick
> Date: Wed Jul 17 04:34:51 2013
> New Revision: 186499
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=186499&view=rev
> Log:
> Tweak the cmake interaction between CMAKE_BUILD_TYPE and LLVM_ENABLE_ASSERTIONS.
> The issue is that CMAKE_BUILD_TYPE=RelWithDebInfo LLVM_ENABLE_ASSERTIONS=ON was
> not building with assertions enabled.  (I was unable to find what in the LLVM
> source tree was adding -DNDEBUG to the build line in this case, so decided that
> it must be cmake itself that was adding it - this may depend on the cmake
> version).  The fix treats any mode that is not Debug as being the same as
> Release for this purpose (previously it was being assumed that cmake would only
> add -DNDEBUG for Release and not for RelWithDebInfo or MinSizeRel).  If other
> versions of cmake don't add -DNDEBUG for RelWithDebInfo then that's OK: with
> this change you just get a useless but harmless -UNDEBUG or -DNDEBUG.
> 
> I believe this change broke my build setup. Previously a default cmake setup (with no CMAKE_BUILD_TYPE set) would build with no debug, no optimization, and assertions enabled (a pretty good default setup for development). Now we get no assertions in that setup. Was that deliberate?
>  
> Modified:
>     llvm/trunk/CMakeLists.txt
>     llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
> 
> Modified: llvm/trunk/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/CMakeLists.txt?rev=186499&r1=186498&r2=186499&view=diff
> ==============================================================================
> --- llvm/trunk/CMakeLists.txt (original)
> +++ llvm/trunk/CMakeLists.txt Wed Jul 17 04:34:51 2013
> @@ -153,7 +153,7 @@ endif()
>  option(LLVM_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
>  option(LLVM_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
> 
> -if( uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE" )
> +if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
>    option(LLVM_ENABLE_ASSERTIONS "Enable assertions" OFF)
>  else()
>    option(LLVM_ENABLE_ASSERTIONS "Enable assertions" ON)
> 
> Modified: llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/modules/HandleLLVMOptions.cmake?rev=186499&r1=186498&r2=186499&view=diff
> ==============================================================================
> --- llvm/trunk/cmake/modules/HandleLLVMOptions.cmake (original)
> +++ llvm/trunk/cmake/modules/HandleLLVMOptions.cmake Wed Jul 17 04:34:51 2013
> @@ -17,9 +17,9 @@ if( LLVM_ENABLE_ASSERTIONS )
>    if( NOT MSVC )
>      add_definitions( -D_DEBUG )
>    endif()
> -  # On Release builds cmake automatically defines NDEBUG, so we
> +  # On non-Debug builds cmake automatically defines NDEBUG, so we
>    # explicitly undefine it:
> -  if( uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE" )
> +  if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
>      add_definitions( -UNDEBUG )
>      # Also remove /D NDEBUG to avoid MSVC warnings about conflicting defines.
>      string (REGEX REPLACE "(^| )[/-]D *NDEBUG($| )" " "
> 
> 
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