[llvm] r242102 - [CMake] We shouldn't be storing values in the cache unless they actually need CMake cache behavior.

[Chris Bieneman]

> On Jul 16, 2015, at 8:35 AM, Daniel Sanders <Daniel.Sanders at imgtec.com> wrote:
> 
> Hi Chris,
> 
> This isn't a problem but I thought I should mention it. One side effect of this change is that these variables are no longer present in ccmake's interface unless you have already set them manually. I'm in the habit of running cmake to get an initial config then ccmake to edit these variables so I was confused by their sudden disappearance :-).
> 
>> There is also a temporary change to remove non-default values from the
>> cache if they are already present. This should have the impact of cleaning out
>> unncecissary values from the caches on the buildbots and people's local build
>> directories.
> 
> Did you mean "non-default" there?

That is basically what I meant. If they are non-default then caching them has no value other than populating the UIs and causing issues because CMake doesn’t implement any form of cache invalidation.

I generally thing these options are advanced user options that are not commonly used, so I really want to avoid having them in the cache unless they are specified by the user explicitly.

-Chris

> 
>> -----Original Message-----
>> From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-
>> bounces at cs.uiuc.edu] On Behalf Of Chris Bieneman
>> Sent: 14 July 2015 02:18
>> To: llvm-commits at cs.uiuc.edu
>> Subject: [llvm] r242102 - [CMake] We shouldn't be storing values in the cache
>> unless they actually need CMake cache behavior.
>> 
>> Author: cbieneman
>> Date: Mon Jul 13 20:17:43 2015
>> New Revision: 242102
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=242102&view=rev
>> Log:
>> [CMake] We shouldn't be storing values in the cache unless they actually
>> need CMake cache behavior.
>> 
>> add_llvm_external_project puts
>> LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR into the cache even if it is
>> just the in-tree default path. This causes all sorts of oddness, and makes it so
>> that I can't change the behavior of this variable.
>> 
>> This patch never puts LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR into
>> the cache. It will only end up in the cache if it is specified on the command
>> line, which is the correct behavior.
>> 
>> There is also a temporary change to remove non-default values from the
>> cache if they are already present. This should have the impact of cleaning out
>> unncecissary values from the caches on the buildbots and people's local build
>> directories. This part of the change is marked with a TODO and can be
>> removed in a few days.
>> 
>> Modified:
>>    llvm/trunk/cmake/modules/AddLLVM.cmake
>> 
>> Modified: llvm/trunk/cmake/modules/AddLLVM.cmake
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/cmake/modules/AddLLVM.cmake?rev=242102&r1=24210
>> 1&r2=242102&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/cmake/modules/AddLLVM.cmake (original)
>> +++ llvm/trunk/cmake/modules/AddLLVM.cmake Mon Jul 13 20:17:43 2015
>> @@ -689,10 +689,15 @@ macro(add_llvm_external_project name)
>>   list(APPEND LLVM_IMPLICIT_PROJECT_IGNORE
>> "${CMAKE_CURRENT_SOURCE_DIR}/${add_llvm_external_dir}")
>>   string(REPLACE "-" "_" nameUNDERSCORE ${name})
>>   string(TOUPPER ${nameUNDERSCORE} nameUPPER)
>> -  set(LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR
>> "${CMAKE_CURRENT_SOURCE_DIR}/${add_llvm_external_dir}"
>> -      CACHE PATH "Path to ${name} source directory")
>> -  if (NOT ${LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR} STREQUAL ""
>> -      AND EXISTS
>> ${LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR}/CMakeLists.txt)
>> +  #TODO: Remove this check in a few days once it has circulated through
>> +  # buildbots and people's checkouts (cbieneman - July 14, 2015)
>> +  if(${LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR} STREQUAL
>> "${CMAKE_CURRENT_SOURCE_DIR}/${add_llvm_external_dir}")
>> +    unset(LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR CACHE)
>> +  endif()
>> +  if(NOT LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR)
>> +    set(LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR
>> "${CMAKE_CURRENT_SOURCE_DIR}/${add_llvm_external_dir}")
>> +  endif()
>> +  if (EXISTS
>> ${LLVM_EXTERNAL_${nameUPPER}_SOURCE_DIR}/CMakeLists.txt)
>>     option(LLVM_EXTERNAL_${nameUPPER}_BUILD
>>            "Whether to build ${name} as part of LLVM" ON)
>>     if (LLVM_EXTERNAL_${nameUPPER}_BUILD)
>> 
>> 
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