[Regression] Build fails on Linux Armv7

[colemancda]

Describe the bug
I am trying to compile Swift with the buildbot_linux,no_test preset and the build fails.

Steps To Reproduce
Steps to reproduce the behavior:

1. Clone and Swift 5.7.1 sources on Debian 11 Armhf
2. Build with ./swift/utils/build-script --preset=buildbot_linux,no_test
   ...

Expected behavior
The build process should not fail. This previously worked with Swift 5.1.5.

Environment (please fill out the following information)

• OS: Debian Bullseye armhf
• Swift: swift-5.7.1-RELEASE

Additional context

swift-linux-armv7.log

Running on CTL J4+ Chromebook with Cadmium.

[colemancda]

@buttaface Do you have any patches to deal with the libdispatch build errors on Android Armv7?

[colemancda]

I was able to get past the libdispatch failure with --extra-cmake-options='-DCMAKE_C_FLAGS="-w" -DCMAKE_CXX_FLAGS="-w"'

coleman@ctl-j4:~/Developer/swift-source$ ./swift/utils/build-script --assertions --swift-enable-ast-verifier=0 --no-swift-stdlib-assertions '--swift-install-components=autolink-driver;compiler;clang-resource-dir-symlink;stdlib;swift-remote-mirror;sdk-overlay;parser-lib;static-mirror-lib;toolchain-tools;license;sourcekit-inproc' '--llvm-install-components=llvm-cov;llvm-profdata;IndexStore;clang;clang-resource-headers;compiler-rt;clangd;lld;LTO;clang-features-file' --llbuild --swiftpm --swift-driver --xctest --libicu --swiftdocc --build-ninja --install-llvm --install-swift --install-lldb --install-llbuild --install-swiftpm --install-swift-driver --install-xctest --install-libicu --install-prefix=/usr --install-sourcekit-lsp --install-swiftdocc --build-swift-static-stdlib --build-swift-static-sdk-overlay --build-swift-stdlib-unittest-extra --test-installable-package --toolchain-benchmarks --install-destdir=/home/coleman/Developer/swift-source/install --installable-package=/home/coleman/Developer/swift-source/install/swift-5.7.1-armv7-RELEASE-Debian11.tar.gz --relocate-xdg-cache-home-under-build-subdir --build-subdir=buildbot_linux --lldb --release --test --validation-test --long-test --stress-test --test-optimized --foundation --libdispatch --indexstore-db --sourcekit-lsp --skip-test-sourcekit-lsp --swiftdocc '--lit-args=-v --time-tests' --lldb-test-swift-only --install-foundation --install-libdispatch --reconfigure --skip-test-cmark --skip-test-lldb --skip-test-swift --skip-test-llbuild --skip-test-swiftpm --skip-test-swift-driver --skip-test-xctest --skip-test-foundation --skip-test-libdispatch --skip-test-playgroundsupport --skip-test-libicu --skip-test-indexstore-db --skip-test-sourcekit-lsp --skip-test-swiftdocc  --extra-cmake-options='-DCMAKE_C_FLAGS="-w" -DCMAKE_CXX_FLAGS="-w"'

[finagolfin]

No, this seems specific to glibc/armv7, I have not seen it with bionic/armv7, which built fine last week (I have not run that 5.7.1 armv7 build yet, but 5.7 mostly worked fine). I did make other modifications for 32-bit ARM with the 5.7 update, such as turning bootstrapping off because the resulting compiler segfaults.

I also had to modify trunk last month, one of which @eeckstein later remedied in #61868.

[colemancda]

@buttaface From what I understood looking at your Termux build script, you are cross compiling from x86_64 to Armv7, and relying on the official Ubuntu releases, that's also how you are able to disable bootstrapping, because you already have an existing compiler.

[finagolfin]

Yes, but there's no need for that official host x86_64 Swift compiler to cross-compile the Swift compiler itself for armv7 once you disable bootstrapping. I do use the official host x86_64 Swift compiler to then cross-compile the stdlib and the rest of the toolchain, but if you're building natively on armv7, you can just use the natively-built compiler with bootstrapping similarly turned off. In other words, turning bootstrapping off should work no matter what.

[colemancda]

Ok, I will try both approaches. Thanks for the info. I also wanted to know are all the patches in that swift package folder being applied? Or only some? Which ones besides https://github.com/termux/termux-packages/blob/master/packages/swift/swift-include-swift-AST-Expr.h.patch ?

[finagolfin]

Yes, all of them, though most are specific to Android and so will not be relevant to linux armv7.

[colemancda]

After applying patches and building with

--extra-cmake-options='-DCMAKE_C_FLAGS="-w" -DCMAKE_CXX_FLAGS="-w"'
--bootstrapping=off

I get the following error:

/home/coleman/Developer/swift-source/build/buildbot_linux/swift-linux-armv7/stdlib/public/core/4/Tuple.swift
/home/coleman/Developer/swift-source/build/buildbot_linux/swift-linux-armv7/stdlib/public/core/4/SIMDConcreteOperations.swift
/home/coleman/Developer/swift-source/build/buildbot_linux/swift-linux-armv7/stdlib/public/core/4/SIMDVectorTypes.swift
---
4.      While evaluating request ExecuteSILPipelineRequest(Run pipelines { Mandatory Diagnostic Passes + Enabling Optimization Passes } on SIL for Swift)
5.      While running pass #174401 SILFunctionTransform "PredictableDeadAllocationElimination" on SILFunction "@$ss7UnicodeO12_InternalNFCV8IteratorV13composeHangul_3andAB6ScalarVSgAJ_AJtF".
 for 'composeHangul(_:and:)' (at /home/coleman/Developer/swift-source/swift/stdlib/public/core/NFC.swift:63:12)
<unknown>:0: error: unable to execute command: Aborted
<unknown>:0: error: compile command failed due to signal 6 (use -v to see invocation)
[372/621][ 59%][4415.763s] Linking CXX executable bin/sil-func-extractor
ninja: build stopped: subcommand failed.
ERROR: command terminated with a non-zero exit status 1, aborting

[finagolfin]

Huh, that's strange: you built the Swift compiler natively but it couldn't build the stdlib, even though it works when cross-compiling the stdlib? Could you check and see if bootstrapping is really turned off, either by running readelf -d build/Ninja-Release/swift-linux-armv7/bin/swift-frontend or ag bootstrap build/Ninja-Release/swift-linux-armv7/CMakeCache.txt?

[colemancda]

coleman@ctl-j4:~/Developer/swift-source$ readelf -d build/buildbot_linux/swift-linux-armv7/bin/swift-frontend

Dynamic section at offset 0x8c74eb4 contains 36 entries:
  Tag        Type                         Name/Value
 0x00000003 (PLTGOT)                     0x8c99eb0
 0x00000002 (PLTRELSZ)                   2864 (bytes)
 0x00000017 (JMPREL)                     0xd0b0
 0x00000014 (PLTREL)                     REL
 0x00000011 (REL)                        0xcfb0
 0x00000012 (RELSZ)                      256 (bytes)
 0x00000013 (RELENT)                     8 (bytes)
 0x00000015 (DEBUG)                      0x0
 0x00000006 (SYMTAB)                     0x81f4
 0x0000000b (SYMENT)                     16 (bytes)
 0x00000005 (STRTAB)                     0x9a14
 0x0000000a (STRSZ)                      9630 (bytes)
 0x6ffffef5 (GNU_HASH)                   0xbfb4
 0x00000004 (HASH)                       0xc000
 0x00000001 (NEEDED)                     Shared library: [libpthread.so.0]
 0x00000001 (NEEDED)                     Shared library: [libdl.so.2]
 0x00000001 (NEEDED)                     Shared library: [libatomic.so.1]
 0x00000001 (NEEDED)                     Shared library: [libuuid.so.1]
 0x00000001 (NEEDED)                     Shared library: [librt.so.1]
 0x00000001 (NEEDED)                     Shared library: [libm.so.6]
 0x00000001 (NEEDED)                     Shared library: [libtinfo.so.6]
 0x00000001 (NEEDED)                     Shared library: [libstdc++.so.6]
 0x00000001 (NEEDED)                     Shared library: [libgcc_s.so.1]
 0x00000001 (NEEDED)                     Shared library: [libc.so.6]
 0x00000001 (NEEDED)                     Shared library: [ld-linux-armhf.so.3]
 0x0000000c (INIT)                       0xdbe0
 0x0000000d (FINI)                       0x600feb8
 0x0000001a (FINI_ARRAY)                 0x87eb328
 0x0000001c (FINI_ARRAYSZ)               4 (bytes)
 0x00000019 (INIT_ARRAY)                 0x87eb32c
 0x0000001b (INIT_ARRAYSZ)               2132 (bytes)
 0x0000001d (RUNPATH)                    Library runpath: [/home/coleman/Developer/swift-source/build/buildbot_linux/llvm-linux-armv7/./lib:]
 0x6ffffff0 (VERSYM)                     0xca2c
 0x6ffffffe (VERNEED)                    0xcd30
 0x6fffffff (VERNEEDNUM)                 9
 0x00000000 (NULL)                       0x0

[colemancda]

/home/coleman/Developer/swift-source/build/buildbot_linux/swift-linux-armv7/CMakeCache.txt

//How to build the swift compiler modules. Possible values are
//\n    OFF:           build without swift modules
//\n    HOSTTOOLS:     build with a pre-installed toolchain
//\n    BOOTSTRAPPING: build with a 2-stage bootstrapping process
//\n    BOOTSTRAPPING-WITH-HOSTLIBS:   build with a 2-stage bootstrapping
// process,
//\n                   but the compiler links against the host system
// swift libs (macOS only)
//\n    CROSSCOMPILE:  cross-compiledwith a native host compiler,
// provided in
//\n                   `SWIFT_NATIVE_SWIFT_TOOLS_PATH` (non-Darwin
// only)
//\n    CROSSCOMPILE-WITH-HOSTLIBS:    build with a bootstrapping-with-hostlibs
// compiled
//\n                                   compiler, provided in `SWIFT_NATIVE_SWIFT_TOOLS_PATH`
//\n
BOOTSTRAPPING_MODE:STRING=OFF