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

[Pete Cooper]

On Sep 20, 2013, at 10:56 AM, Tilmann Scheller <tscheller at apple.com> wrote:

> IMHO we should make an unspecified CMAKE_BUILD_TYPE just default to Debug+Asserts (this would also increase consistency with the Makefile build).
I agree
> 
> 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!
Strange.  The LLVM cmake documentation implies that debug should have enabled asserts, that is it says that:

"LLVM_ENABLE_ASSERTIONS:BOOL
Enables code assertions. Defaults to OFF if and only if CMAKE_BUILD_TYPE is Release.
"
> 
> 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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