[llvm] r320413 - [cmake] Pass TARGETS_TO_BUILD through to host tools build

[Alex Bradbury via llvm-commits]

On 11 December 2017 at 19:53, Justin Bogner via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: bogner
> Date: Mon Dec 11 11:53:23 2017
> New Revision: 320413
>
> URL: http://llvm.org/viewvc/llvm-project?rev=320413&view=rev
> Log:
> [cmake] Pass TARGETS_TO_BUILD through to host tools build
>
> In r319620, the host build was changed to use Native for
> TARGETS_TO_BUILD because passing semicolons through add_custom_command
> is surprisingly difficult. However, Native really doesn't make any
> sense here, and it only works because we don't technically do any
> codegen in the host tools so pretty well anything will "work".
>
> The problem here is that passing something other than the correct
> value is very fragile - as evidence note how the llvm-config in the
> host tools acts differently than the target one now, and misreports
> the targets to build. Similarly, if there is any logic conditional on
> the targets in tablegen (now or in the future), it will do the wrong
> thing.
>
> To fix this, we need to escape the semicolons in the targets string
> and pass it through to the child cmake invocation.

Hi Justin. This breaks builds which set targets through
LLVM_EXPERIMENTAL_TARGETS_TO_BUILD (in my case, the RISCV backend when
building with -DLLVM_OPTIMIZED_TABLEGEN=True). I'm not familiar enough
with the CMake internals and the problem this patch fixes to suggest a
minimal fix. Part of the problem is that at this point
LLVM_EXPERIMENTAL_TARGETS_TO_BUILD has already been merged in to
LLVM_TARGETS_TO_BUILD. Is it desirable to set
LLVM_EXPERIMENTAL_TARGETS_TO_BUILD for the host build?


Excerpt from failed configure:

[1/1] Configuring NATIVE LLVM...
FAILED: NATIVE/CMakeCache.txt
cd /local/scratch/asb58/llvm-repos/llvm/build_for_upstream/NATIVE &&
/local/scratch/asb58/cmake-3.5.2-Linux-x86_64/bin/cmake -G Ninja
-DCMAKE_C_COMPILER=/usr/bin/clang-3.8
-DCMAKE_CXX_COMPILER=/usr/bin/clang++-3.8
/local/scratch/asb58/llvm-repos/llvm
-DLLVM_TARGET_IS_CROSSCOMPILE_HOST=TRUE
-DLLVM_TARGETS_TO_BUILD="AArch64;AMDGPU;ARM;BPF;Hexagon;Lanai;Mips;MSP430;NVPTX;PowerPC;Sparc;SystemZ;X86;XCore;RISCV"
-DCMAKE_BUILD_TYPE=Release
-- Native target architecture is X86
-- Threads enabled.
-- Doxygen disabled.
-- Go bindings enabled.
-- Could NOT find OCaml (missing:  OCAMLFIND OCAML_VERSION OCAML_STDLIB_PATH)
-- Could NOT find OCaml (missing:  OCAMLFIND OCAML_VERSION OCAML_STDLIB_PATH)
-- OCaml bindings disabled.
-- Could NOT find Python module pygments
-- Could NOT find Python module yaml
-- LLVM host triple: x86_64-unknown-linux-gnu
-- LLVM default target triple: x86_64-unknown-linux-gnu
-- Building with -fPIC
-- Constructing LLVMBuild project information
CMake Error at CMakeLists.txt:682 (message):
  The target `RISCV' does not exist.

      It should be one of


  AArch64;AMDGPU;ARM;BPF;Hexagon;Lanai;Mips;MSP430;NVPTX;PowerPC;Sparc;SystemZ;X86;XCore


-- Configuring incomplete, errors occurred!
See also "/local/scratch/asb58/llvm-repos/llvm/build_for_upstream/NATIVE/CMakeFiles/CMakeOutput.log".
See also "/local/scratch/asb58/llvm-repos/llvm/build_for_upstream/NATIVE/CMakeFiles/CMakeError.log".
ninja: build stopped: subcommand failed.