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 .]
>
> On 2019-Aug-6, at 20:23, Mark Millard <marklmi at yahoo.com> wrote:
>
>
>
> > On 2019-Aug-6, at 19:08, Brooks Davis <brooks at freebsd.org> wrote:
> >
> >> On Tue, Aug 06, 2019 at 05:59:21PM -0700, Mark Millard wrote:
> >>>
> >>>
> >>> On 2019-Aug-6, at 09:55, Brooks Davis <brooks at freebsd.org> wrote:
> >>>
> >>>> 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.
> >>>>
> >>>> -- Brooks
> >>>
> >>> Okay.
> >>>
> >>> 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.
> >>
> >> 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.
> >
> >
> > I hope this helps. (I'm not a cmake expert.)
> >
> > llvm-9.0.0rc1.src/lib/Support/Z3Solver.cpp does:
> >
> > #if LLVM_WITH_Z3
> >
> > #include <z3.h>
> >
> > namespace {
> > . . .
> > } // end anonymous namespace
> >
> > #endif
> >
> > 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=ON",
> > false);
> > return nullptr;
> > #endif
> > }
> >
> > (There are other places LLVM_WITH_Z3 is used but the
> > above is suggestive.)
> >
> > Working backwards finds that:
> >
> > /wrkdirs/usr/ports/devel/llvm90/work/llvm-9.0.0rc1.src/CMakeLists.txt
> >
> > shows LLVM_WITH_Z3 being conditionally set to 1 via . . .
> >
> > set(LLVM_Z3_INSTALL_DIR "" CACHE STRING "Install directory of the Z3
> > solver.")
> >
> > find_package(Z3 4.7.1)
> >
> > if (LLVM_Z3_INSTALL_DIR)
> > if (NOT Z3_FOUND)
> > message(FATAL_ERROR "Z3 >= 4.7.1 has not been found in
> > LLVM_Z3_INSTALL_DIR: ${LLVM_Z3_INSTALL_DIR}.")
> > endif()
> > endif()
> >
> > set(LLVM_ENABLE_Z3_SOLVER_DEFAULT "${Z3_FOUND}")
> >
> > option(LLVM_ENABLE_Z3_SOLVER
> > "Enable Support for the Z3 constraint solver in LLVM."
> > ${LLVM_ENABLE_Z3_SOLVER_DEFAULT}
> > )
> >
> > 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()
> >
> > set(LLVM_WITH_Z3 1)
> > endif()
> >
> > if( LLVM_TARGETS_TO_BUILD STREQUAL "all" )
> > set( LLVM_TARGETS_TO_BUILD ${LLVM_ALL_TARGETS} )
> > endif()
> >
> >
> > If I read that correctly, LLVM_ENABLE_Z3_SOLVER set directly
> > appears to override the default (that tracks if z3 was found).
>
> I saw a reference to:
>
> diff --git a/llvm/cmake/modules/CrossCompile.cmake
> b/llvm/cmake/modules/CrossCompile.cmake
> index bc3b210f018..0c30b88f80f 100644
> --- a/llvm/cmake/modules/CrossCompile.cmake
> +++ b/llvm/cmake/modules/CrossCompile.cmake
> @@ -53,6 +53,7 @@ function(llvm_create_cross_target_internal target_name
> toolchain buildtype)
> -DLLVM_DEFAULT_TARGET_TRIPLE="${TARGET_TRIPLE}"
> -DLLVM_TARGET_ARCH="${LLVM_TARGET_ARCH}"
>
> -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN="${LLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN}"
> + -DLLVM_ENABLE_Z3_SOLVER="${LLVM_ENABLE_Z3_SOLVER}"
> ${build_type_flags} ${linker_flag} ${external_clang_dir}
> WORKING_DIRECTORY ${LLVM_${target_name}_BUILD}
> DEPENDS CREATE_LLVM_${target_name}
>
> in https://reviews.llvm.org/D54978 on Feb 12 2019, 5:41 PM
> and it had the comment:
>
> 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
>
> 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.)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: 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+=libz3.so:math/z3 I've generally observed that the portions of the system that cover lit (which includes FileCheck) aren't very well behaved. -- Brooks
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