Date: Wed, 7 Aug 2019 11:55:04 -0700 From: Mark Millard <marklmi@yahoo.com> To: Brooks Davis <brooks@freebsd.org> Cc: freebsd-toolchain@freebsd.org, freebsd-ports@freebsd.org, freebsd-ppc@freebsd.org Subject: Re: devel/llvm90 requires math/z3 first; building math/z3 requires a c++ toolchain be in place Message-ID: <4FF9540B-E1FE-4947-8E45-8D4FB57A7E34@yahoo.com> In-Reply-To: <20190807180244.GJ94703@spindle.one-eyed-alien.net> References: <8DB3EAA4-2B88-4180-8386-673524D27C64@yahoo.com> <20190806165525.GC94703@spindle.one-eyed-alien.net> <2A88AADC-8ED0-4FFD-85A8-34C0186D5D4F@yahoo.com> <20190807020826.GH94703@spindle.one-eyed-alien.net> <602EEB6C-D0B0-4EFB-AB0E-BE98FF1C4D90@yahoo.com> <086C99B8-1289-4D81-AAF5-85FB0AE70B7C@yahoo.com> <20190807171714.GI94703@spindle.one-eyed-alien.net> <20190807180244.GJ94703@spindle.one-eyed-alien.net>
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On 2019-Aug-7, at 11:02, Brooks Davis <brooks at freebsd.org> wrote:
> On Wed, Aug 07, 2019 at 05:17:14PM +0000, Brooks Davis wrote:
>> On Tue, Aug 06, 2019 at 09:22:52PM -0700, Mark Millard wrote:
>>> [I found something known to be missing in the
>>> in at least some versions of
>>> llvm/cmake/modules/CrossCompile.cmake that messes
>>> up the overall handling of LLVM_ENABLE_Z3_SOLVER .]
>>>=20
>>> On 2019-Aug-6, at 20:23, Mark Millard <marklmi at yahoo.com> wrote:
>>>=20
>>>=20
>>>=20
>>>> On 2019-Aug-6, at 19:08, Brooks Davis <brooks at freebsd.org> =
wrote:
>>>>=20
>>>>> On Tue, Aug 06, 2019 at 05:59:21PM -0700, Mark Millard wrote:
>>>>>>=20
>>>>>>=20
>>>>>> On 2019-Aug-6, at 09:55, Brooks Davis <brooks at freebsd.org> =
wrote:
>>>>>>=20
>>>>>>> I'd prefer to disable this dependency. There's a knob that =
worked in
>>>>>>> the 8.0 timeframe, but the lit build now autodetects z3 when it =
is
>>>>>>> present and I've failed to find a knob to disable it. For now, =
the easy
>>>>>>> workaround is probably to disable options LIT. We could make =
that the
>>>>>>> default on non-LLVM platforms is that makes sense.
>>>>>>>=20
>>>>>>> -- Brooks
>>>>>>=20
>>>>>> Okay.
>>>>>>=20
>>>>>> poudriere-devel automatically built math/z3 because
>>>>>> I'd indicated to build devel/llvm90 . math/z3 was not
>>>>>> previously built: I've never had other use of it. So
>>>>>> my context was not one of an implicit autodetect.
>>>>>=20
>>>>> The dependency is there because if z3 is installed then the =
package
>>>>> that is built depends on z3. Thus I had not choice but to add a =
z3
>>>>> dependency until I find a way to turn it off. You can either help =
find
>>>>> a way to disable z3 detection in the cmake infrastructure or turn =
off
>>>>> LIT. I don't have any use for reports on the effects of =
commenting out
>>>>> the DEPENDS line. I know what that does.
>>>>=20
>>>>=20
>>>> I hope this helps. (I'm not a cmake expert.)
>>>>=20
>>>> llvm-9.0.0rc1.src/lib/Support/Z3Solver.cpp does:
>>>>=20
>>>> #if LLVM_WITH_Z3
>>>>=20
>>>> #include <z3.h>
>>>>=20
>>>> namespace {
>>>> . . .
>>>> } // end anonymous namespace
>>>>=20
>>>> #endif
>>>>=20
>>>> llvm::SMTSolverRef llvm::CreateZ3Solver() {
>>>> #if LLVM_WITH_Z3
>>>> return llvm::make_unique<Z3Solver>();
>>>> #else
>>>> llvm::report_fatal_error("LLVM was not compiled with Z3 support, =
rebuild "
>>>> "with -DLLVM_ENABLE_Z3_SOLVER=3DON",
>>>> false);
>>>> return nullptr;
>>>> #endif
>>>> }
>>>>=20
>>>> (There are other places LLVM_WITH_Z3 is used but the
>>>> above is suggestive.)
>>>>=20
>>>> Working backwards finds that:
>>>>=20
>>>> =
/wrkdirs/usr/ports/devel/llvm90/work/llvm-9.0.0rc1.src/CMakeLists.txt
>>>>=20
>>>> shows LLVM_WITH_Z3 being conditionally set to 1 via . . .
>>>>=20
>>>> set(LLVM_Z3_INSTALL_DIR "" CACHE STRING "Install directory of the =
Z3 solver.")
>>>>=20
>>>> find_package(Z3 4.7.1)
>>>>=20
>>>> if (LLVM_Z3_INSTALL_DIR)
>>>> if (NOT Z3_FOUND)
>>>> message(FATAL_ERROR "Z3 >=3D 4.7.1 has not been found in =
LLVM_Z3_INSTALL_DIR: ${LLVM_Z3_INSTALL_DIR}.")
>>>> endif()
>>>> endif()
>>>>=20
>>>> set(LLVM_ENABLE_Z3_SOLVER_DEFAULT "${Z3_FOUND}")
>>>>=20
>>>> option(LLVM_ENABLE_Z3_SOLVER
>>>> "Enable Support for the Z3 constraint solver in LLVM."
>>>> ${LLVM_ENABLE_Z3_SOLVER_DEFAULT}
>>>> )
>>>>=20
>>>> if (LLVM_ENABLE_Z3_SOLVER)
>>>> if (NOT Z3_FOUND)
>>>> message(FATAL_ERROR "LLVM_ENABLE_Z3_SOLVER cannot be enabled when =
Z3 is not available.")
>>>> endif()
>>>>=20
>>>> set(LLVM_WITH_Z3 1)
>>>> endif()
>>>>=20
>>>> if( LLVM_TARGETS_TO_BUILD STREQUAL "all" )
>>>> set( LLVM_TARGETS_TO_BUILD ${LLVM_ALL_TARGETS} )
>>>> endif()
>>>>=20
>>>>=20
>>>> If I read that correctly, LLVM_ENABLE_Z3_SOLVER set directly
>>>> appears to override the default (that tracks if z3 was found).
>>>=20
>>> I saw a reference to:
>>>=20
>>> diff --git a/llvm/cmake/modules/CrossCompile.cmake =
b/llvm/cmake/modules/CrossCompile.cmake
>>> index bc3b210f018..0c30b88f80f 100644
>>> --- a/llvm/cmake/modules/CrossCompile.cmake
>>> +++ b/llvm/cmake/modules/CrossCompile.cmake
>>> @@ -53,6 +53,7 @@ function(llvm_create_cross_target_internal =
target_name toolchain buildtype)
>>> -DLLVM_DEFAULT_TARGET_TRIPLE=3D"${TARGET_TRIPLE}"
>>> -DLLVM_TARGET_ARCH=3D"${LLVM_TARGET_ARCH}"
>>> =
-DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=3D"${LLVM_TEMPORARILY_ALLOW_OLD_TOO=
LCHAIN}"
>>> + -DLLVM_ENABLE_Z3_SOLVER=3D"${LLVM_ENABLE_Z3_SOLVER}"
>>> ${build_type_flags} ${linker_flag} ${external_clang_dir}
>>> WORKING_DIRECTORY ${LLVM_${target_name}_BUILD}
>>> DEPENDS CREATE_LLVM_${target_name}
>>>=20
>>> in https://reviews.llvm.org/D54978 on Feb 12 2019, 5:41 PM
>>> and it had the comment:
>>>=20
>>> QUOTE
>>> Independent of the rest of the discussion, this patch should be part =
of the reland, to make sure that explicitly turning off Z3 works =
reliably. Thanks for coming up with that, and thanks everyone for the =
good discussion here :)
>>> END QUOTE
>>>=20
>>> This apparently fixes a sub-cmake not respecting the
>>> LLVM_ENABLE_Z3_SOLVER setting in the parent cmake.
>>> (The overall review earlier describes the sub-cmake
>>> not doing the right thing.)
>>=20
>> Thanks for digging this up. Unfortunately, this doesn't seem to have
>> solved the problem. With this patch applied I still get this if I =
have
>> z3 installed on the system and no LIB_DEPENDS line:
>>=20
>> Error: /usr/local/bin/FileCheck90 is linked to =
/usr/local/lib/libz3.so.0
>> from math/z3 but it is not declared as a dependency
>> Warning: you need LIB_DEPENDS+=3Dlibz3.so:math/z3
>>=20
>> I've generally observed that the portions of the system that cover =
lit
>> (which includes FileCheck) aren't very well behaved.
>=20
> I've filed https://bugs.llvm.org/show_bug.cgi?id=3D42921 upstream,
> hopefully someone who understand this part of the cmake system will =
help
> us out.
You mentioned applying the patch but not also
setting:
LLVM_ENABLE_Z3_SOLVER:BOOL=3DOFF
with either:
-D LLVM_ENABLE_Z3_SOLVER:BOOL=3DOFF
on the command line or some line early in CMakeCache.txt .
(Actually, I had to look around to know to say those
specifics of what it means to have already initialized
LLVM_ENABLE_Z3_SOLVER .)
=46rom what I see, taking the initial assignment via CMakeCache.txt
after it is initialized seems to be a common technique of controlling
the configuration.
Taking from an example from web of a CMakeCache.txt . . .
# This is the CMakeCache file.
# For build in directory: [edited out]
# It was generated by CMake: /Applications/CMake.app/Contents/bin/cmake
# You can edit this file to change values found and used by cmake.
# If you do not want to change any of the values, simply exit the =
editor.
# If you do want to change a value, simply edit, save, and exit the =
editor.
# The syntax for the file is as follows:
# KEY:TYPE=3DVALUE
# KEY is the name of a variable in the cache.
# TYPE is a hint to GUIs for the type of VALUE, DO NOT EDIT TYPE!.
# VALUE is the current value for the KEY.
########################
# EXTERNAL cache entries
########################
//Build a 32 bit version of the library.
BENCHMARK_BUILD_32_BITS:BOOL=3DOFF
. . . (lots omitted) . . .
//Fail and stop if a warning is triggered.
LLVM_ENABLE_WERROR:BOOL=3DOFF
//Enable Support for the Z3 constraint solver in LLVM.
LLVM_ENABLE_Z3_SOLVER:BOOL=3DOFF
//Use zlib for compression/decompression if available.
LLVM_ENABLE_ZLIB:BOOL=3DON
. . . (lots more omitted) . . .
The example already had the "LLVM_ENABLE_Z3_SOLVER:BOOL=3DOFF"
line, I did not adjust it.
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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