Problems with x86_32 Build

[calein]

Hi,

I have problems building a 32 bit version of Halide libs on Linux. I tired both, building it on a 32 bit Linux (Xubuntu 18.04) and building it on a 64 bit Linux (Ubuntu 18.04) with the provided 32 bit toolchain. Building 64 bit Halide on 64 bit Linux works. Can maybe someone help me out?

32 bit Host

On 32 bit Linux I initialize the build via the following command:

cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -S . -B build

The Output is:

-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Halide detected current CMake target:  i686-32-linux
-- Halide using default generator target: host
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Check if compiler accepts -pthread
-- Check if compiler accepts -pthread - yes
-- Found Threads: TRUE  
-- Could NOT find OpenGL (missing: OPENGL_opengl_LIBRARY OPENGL_glx_LIBRARY OPENGL_INCLUDE_DIR) 
-- Found OpenMP_C: -fopenmp (found version "4.5") 
-- Found OpenMP_CXX: -fopenmp (found version "4.5") 
-- Found OpenMP: TRUE (found version "4.5")  
-- Found LLVM 10.0.0
-- Using LLVMConfig.cmake in: /usr/lib/llvm-10/cmake
-- Enabling AArch64 backend
-- Enabling AMDGPU backend
-- Enabling ARM backend
-- Enabling Hexagon backend
-- Enabling Mips backend
-- Enabling NVPTX backend
-- Enabling PowerPC backend
-- Enabling RISCV backend
-- Enabling X86 backend
-- Compiling Halide WITH RTTI.
-- Compiling Halide WITH exceptions.
-- Found JPEG: /usr/lib/i386-linux-gnu/libjpeg.so (found version "80") 
-- Found ZLIB: /usr/lib/i386-linux-gnu/libz.so (found version "1.2.11") 
-- Found PNG: /usr/lib/i386-linux-gnu/libpng.so (found version "1.6.34") 
-- Performing Test LINKER_HAS_FLAG_VERSION_SCRIPT
-- Performing Test LINKER_HAS_FLAG_VERSION_SCRIPT - Success
-- Building autoschedulers enabled
-- Building tests enabled
-- Building Python bindings enabled
-- Found Python3: /usr/bin/python3.6 (found version "3.6.9") found components: Interpreter Development Development.Module Development.Embed 
-- pybind11 v2.6.1 
-- Performing Test HAS_FLTO
-- Performing Test HAS_FLTO - Success
-- Building tutorials enabled
-- Building docs disabled
-- Building utils enabled
-- Configuring done
-- Generating done
-- Build files have been written to: /home/user/Halide/source/build

So Halide detected the 32 bit target, as it says

-- Halide detected current CMake target:  i686-32-linux

When I build it via

cmake --build ./build

I get the following build error after some time:

[1728/3323] Generating train_cost_model.h, train_cost_model.o
FAILED: src/autoschedulers/adams2019/train_cost_model.h src/autoschedulers/adams2019/train_cost_model.o 
cd /home/carsten/Halide/source/build/src/autoschedulers/adams2019 && /home/carsten/Halide/source/build/src/autoschedulers/adams2019/cost_model.generator -n train_cost_model -d 0 -g train_cost_model -f train_cost_model -e c_header,object -o . target=i686-32-linux-no_runtime
Unhandled exception: Error: Did not understand Halide target i686-32-linux-no_runtime
Expected format is arch-bits-os-feature1-feature2-...
Where arch is: arch_unknown, arm, hexagon, mips, powerpc, riscv, wasm, x86.
bits is either 32 or 64.
os is: android, fuchsia, ios, linux, noos, os_unknown, osx, qurt, wasmrt, windows.

If arch, bits, or os are omitted, they default to the host.

Features are: arm_dot_prod, armv7s, asan, avx, avx2, avx512, avx512_cannonlake
avx512_knl, avx512_skylake, c_plus_plus_name_mangling, check_unsafe_promises
cl_atomics64, cl_doubles, cl_half, cuda, cuda_capability_30, cuda_capability_32
cuda_capability_35, cuda_capability_50, cuda_capability_61, cuda_capability_70
cuda_capability_75, cuda_capability_80, d3d12compute, debug, disable_llvm_loop_opt
egl, embed_bitcode, enable_llvm_loop_opt, f16c, fma, fma4, fuzz_float_stores
hexagon_dma, hvx, hvx_128, hvx_shared_object, hvx_v62, hvx_v65, hvx_v66
jit, large_buffers, llvm_large_code_model, matlab, metal, msan, no_asserts
no_bounds_query, no_neon, no_runtime, opencl, openglcompute, power_arch_2_07
profile, soft_float_abi, sse41, strict_float, sve, sve2, trace_loads, trace_pipeline
trace_realizations, trace_stores, tsan, user_context, vsx, wasm_bulk_memory
wasm_sat_float_to_int, wasm_signext, wasm_simd128, wasm_threads.

The target can also begin with "host", which sets the host's architecture, os, and feature set, with the exception of the GPU runtimes, which default to off.

On this platform, the host target is: x86-32-linux-avx-sse41

[1729/3323] Building CXX object src/autoschedulers/ada...019/CMakeFiles/demo.generator.dir/demo_generator.cpp.o
ninja: build stopped: subcommand failed.

I already tried to add the suggested Halide target as follows (after removing ./build):

cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -DHalide_TARGET=x86-32-linux-avx-sse41 -S . -B build

However this leads to the same error message.

64 bit Host

On my 64 bit Ubuntu I initialize the build with

cmake -G Ninja -DCMAKE_TOOLCHAIN_FILE=./cmake/toolchain.linux-i386.cmake -DCMAKE_BUILD_TYPE=Release -S . -B build

This gives the following error:

-- The C compiler identification is Clang 10.0.0
-- The CXX compiler identification is Clang 10.0.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Halide detected active CMake target `i686-32-linux`
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Check if compiler accepts -pthread
-- Check if compiler accepts -pthread - yes
-- Found Threads: TRUE  
-- Could NOT find OpenGL (missing: OPENGL_opengl_LIBRARY OPENGL_glx_LIBRARY) 
-- Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES) 
-- Could NOT find OpenMP_CXX (missing: OpenMP_CXX_FLAGS OpenMP_CXX_LIB_NAMES) 
-- Could NOT find OpenMP (missing: OpenMP_C_FOUND OpenMP_CXX_FOUND) 
-- Found LLVM 10.0.0
-- Using LLVMConfig.cmake in: /usr/lib/llvm-10/cmake
-- Enabling AArch64 backend
-- Enabling AMDGPU backend
-- Enabling ARM backend
-- Enabling Hexagon backend
-- Enabling Mips backend
-- Enabling NVPTX backend
-- Enabling PowerPC backend
-- Enabling RISCV backend
-- Enabling X86 backend
-- Compiling Halide WITH RTTI.
-- Compiling Halide WITH exceptions.
-- Could NOT find JPEG (missing: JPEG_LIBRARY) (found version "80")
-- Found ZLIB: /usr/lib32/libz.so (found version "1.2.11") 
-- Could NOT find PNG (missing: PNG_LIBRARY) (found version "1.6.34")
-- Building autoschedulers enabled
-- Building tests enabled
-- Building Python bindings enabled
CMake Error at /snap/cmake/769/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
  Could NOT find Python3 (missing: Python3_INCLUDE_DIRS Python3_LIBRARIES
  Development Development.Module Development.Embed) (found version "3.6.9")
Call Stack (most recent call first):
  /snap/cmake/769/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
  /snap/cmake/769/share/cmake-3.19/Modules/FindPython/Support.cmake:3148 (find_package_handle_standard_args)
  /snap/cmake/769/share/cmake-3.19/Modules/FindPython3.cmake:398 (include)
  python_bindings/CMakeLists.txt:5 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/user/Halide/source/build/CMakeFiles/CMakeOutput.log".
See also "/home/user/Halide/source/build/CMakeFiles/CMakeError.log".

I suppose that I need 32 bit version Python for that? Interestingly with the i386 toolchain Halide also detects the target i686-32-linux which it did not understand in the build on the 32 bit machine (Error: Did not understand Halide target i686-32-linux-no_runtime).

Best regards
calein

[steven-johnson]

Unhandled exception: Error: Did not understand Halide target i686-32-linux-no_runtime
Expected format is arch-bits-os-feature1-feature2-...
Where arch is: arch_unknown, arm, hexagon, mips, powerpc, riscv, wasm, x86.
bits is either 32 or 64.
os is: android, fuchsia, ios, linux, noos, os_unknown, osx, qurt, wasmrt, windows.

i686-32-linux is not a valid Halide target string. You want x86 as the first segment, i.e., x86-32-linux-no_runtime.

[shoaibkamil]

I think the problem is that our CMake configuration is detecting and passing this invalid target on x86-32. The first time they tried it, it looks like they were not setting a target, and even when they do set Halide_TARGET CMake seems to be passing the CMake target in.

[calein]

Yes I tried it with and without Halide_TARGET=x86-32-linux-avx-sse41 on the 32 bit machine. In both cases it says -- Halide detected active CMake target i686-32-linux. When I use toolchain.linux-i386.cmake on the 64 bit machine it also comes up with CMake target i686.

As a next step I changed the variable CMAKE_SYSTEM_PROCESSOR from i686 to x86 in the toolchain file. I also added -DWITH_PYTHON_BINDINGS=OFF for the initialization of the build on the 64 bit machine as I found here.

On the 64 bit machine it says -- Halide detected active CMake target x86-32-linux. However when I start the build I get the following error:

[14/3219] Generating _initmod_ptx_compute_20.cpp
FAILED: src/runtime/_initmod_ptx_compute_20.cpp 
cd /home/user/Halide/source/build/src/runtime && binary2cpp halide_internal_initmod_ptx_compute_20_ll < /home/user/Halide/source/src/runtime/nvidia_libdevice_bitcode/libdevice.compute_20.10.bc > _initmod_ptx_compute_20.cpp
/bin/sh: 1: binary2cpp: not found
[23/3219] Building CXX object src/autoschedulers/adams2019/CMakeFiles/weightsdir_to_weightsfile.dir/Weights.cpp.o
ninja: build stopped: subcommand failed.

The same error occurs when I use the modified toolchain file on the 32 bit machine or when I use the following command to initialize the build:
cmake -G Ninja -DCMAKE_SYSTEM_NAME=Linux -DCMAKE_SYSTEM_PROCESSOR=x86 -DCMAKE_BUILD_TYPE=Release -S . -B build

The Workaround

I finally was able to build the desired 32 bit Halide on the 32 bit machine by first running cmake -G Ninja -DCMAKE_BUILD_TYPE=Release -S . -B build and then replacing all occurances of i686 by x86 in the build directory. I also had to rename / copy the directory /usr/lib/gcc/i686-linux-gnu to /usr/lib/gcc/x86-linux-gnu.

This however is not very convenient. Can you maybe consider adding an alias for i686 to x86_32 for upcoming releases? Or am I the only one with this problem / do I miss something here?

[steven-johnson]

Ah, ok, I get it. Yeah, this is our fault, the CMake scripts should handle this automatically. Are you building the 32-bit version on a true 32-bit machine (vs crosscompiing on a 64-bit OS)? That may be the issue, as our buildbots are all doing the latter.

Tagging @alexreinking for CMake thoughts.

[alexreinking]

Opened PR #5675

[alexreinking]

@calein - can you please try the change in #5675 and see if it works from a clean build directory?

https://github.com/halide/Halide/pull/5675/files

[calein]

Hi @alexreinking. Yes it works.

I checked out the branch cmake/fix-target-i686 on my (virtual) 32 bit machine and did a clean build. In the initialization step I now get the message -- Halide detected current CMake target: x86-32-linux. However I still don't understand why it works on the buildbot without the fix because when I tried to use the x86-32 toolchain on my 64 ubuntu it also showed -- Halide detected active CMake target i686-32-linux. Does the CMake target name depent on the Linux distro or maybe the CPU family?

[alexreinking]

Great! Glad to hear it works. I will look into what the buildbot's doing and get back to you.

[alexreinking]

I suppose that I need 32 bit version Python for that?

You do need 32-bit Python installed to build the Python bindings against 32-bit Halide.

Also, as a temporary workaround you should be able to set Halide_CMAKE_TARGET and Halide_HOST_TARGET to x86-32-linux.

[steven-johnson]

Note that our buildbots deliberately skip testing of the python bindings on all 32-bit targets -- they may need attention to build properly on some 32 bit systems.