segmentation fault for `aarch64-unknown-none-softfloat` on 0.1.38

[JohnTitor]

Found in rust-lang/rust#79863 (comment):

rustc exited with signal: 11
error: could not compile `compiler_builtins`

Caused by:
  process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc --crate-name compiler_builtins /cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.38/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -C embed-bitcode=no -C codegen-units=10000 -C debuginfo=1 --cfg 'feature="c"' --cfg 'feature="cc"' --cfg 'feature="compiler-builtins"' --cfg 'feature="core"' --cfg 'feature="default"' --cfg 'feature="mem"' --cfg 'feature="rustc-dep-of-std"' -C metadata=11825feb351d960e -C extra-filename=-11825feb351d960e --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage2-std/aarch64-unknown-none-softfloat/release/deps --target aarch64-unknown-none-softfloat -C linker=aarch64-none-elf-gcc -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-std/aarch64-unknown-none-softfloat/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-std/release/deps --extern core=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-std/aarch64-unknown-none-softfloat/release/deps/librustc_std_workspace_core-7dd4080a03583e8c.rmeta --cap-lints allow -Zmacro-backtrace '-Clink-args=-Wl,-rpath,$ORIGIN/../lib' -Cprefer-dynamic -Cembed-bitcode=yes -Z binary-dep-depinfo -L native=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-std/aarch64-unknown-none-softfloat/release/build/compiler_builtins-cf9517a58eb87178/out --cfg 'feature="unstable"' --cfg 'feature="mem"' --cfg '__absvdi2="optimized-c"' --cfg '__absvsi2="optimized-c"' --cfg '__absvti2="optimized-c"' --cfg '__addvdi3="optimized-c"' --cfg '__addvsi3="optimized-c"' --cfg '__addvti3="optimized-c"' --cfg '__clzdi2="optimized-c"' --cfg '__clzsi2="optimized-c"' --cfg '__clzti2="optimized-c"' --cfg '__cmpdi2="optimized-c"' --cfg '__cmpti2="optimized-c"' --cfg '__comparetf2="optimized-c"' --cfg '__ctzdi2="optimized-c"' --cfg '__ctzsi2="optimized-c"' --cfg '__ctzti2="optimized-c"' --cfg '__divdc3="optimized-c"' --cfg '__divsc3="optimized-c"' --cfg '__divxc3="optimized-c"' --cfg '__extenddftf2="optimized-c"' --cfg '__extendhfsf2="optimized-c"' --cfg '__extendsftf2="optimized-c"' --cfg '__ffsti2="optimized-c"' --cfg '__fixtfdi="optimized-c"' --cfg '__fixtfsi="optimized-c"' --cfg '__fixtfti="optimized-c"' --cfg '__fixunstfdi="optimized-c"' --cfg '__fixunstfsi="optimized-c"' --cfg '__fixunstfti="optimized-c"' --cfg '__floatditf="optimized-c"' --cfg '__floatsitf="optimized-c"' --cfg '__floatunditf="optimized-c"' --cfg '__floatunsitf="optimized-c"' --cfg '__int_util="optimized-c"' --cfg '__muldc3="optimized-c"' --cfg '__mulsc3="optimized-c"' --cfg '__multc3="optimized-c"' --cfg '__mulvdi3="optimized-c"' --cfg '__mulvsi3="optimized-c"' --cfg '__mulvti3="optimized-c"' --cfg '__mulxc3="optimized-c"' --cfg '__negdf2="optimized-c"' --cfg '__negdi2="optimized-c"' --cfg '__negsf2="optimized-c"' --cfg '__negti2="optimized-c"' --cfg '__negvdi2="optimized-c"' --cfg '__negvsi2="optimized-c"' --cfg '__negvti2="optimized-c"' --cfg '__paritydi2="optimized-c"' --cfg '__paritysi2="optimized-c"' --cfg '__parityti2="optimized-c"' --cfg '__popcountdi2="optimized-c"' --cfg '__popcountsi2="optimized-c"' --cfg '__popcountti2="optimized-c"' --cfg '__powixf2="optimized-c"' --cfg '__subvdi3="optimized-c"' --cfg '__subvsi3="optimized-c"' --cfg '__subvti3="optimized-c"' --cfg '__truncdfhf2="optimized-c"' --cfg '__truncdfsf2="optimized-c"' --cfg '__truncsfhf2="optimized-c"' --cfg '__trunctfdf2="optimized-c"' --cfg '__trunctfsf2="optimized-c"' --cfg '__ucmpdi2="optimized-c"' --cfg '__ucmpti2="optimized-c"' --cfg 'apple_versioning="optimized-c"' -l static=compiler-rt` (exit code: 254)
warning: build failed, waiting for other jobs to finish...
[RUSTC-TIMING] alloc test:false 3.366
[RUSTC-TIMING] core test:false 19.307
error: build failed
command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "aarch64-unknown-none-softfloat" "-Zbinary-dep-depinfo" "-j" "16" "--release" "--locked" "--color" "always" "-p" "alloc" "--manifest-path" "/checkout/library/alloc/Cargo.toml" "--features" "compiler-builtins-mem compiler-builtins-c" "--message-format" "json-render-diagnostics"
expected success, got: exit code: 101
failed to run: /checkout/obj/build/bootstrap/debug/bootstrap dist --host= --target asmjs-unknown-emscripten,wasm32-unknown-emscripten,x86_64-rumprun-netbsd,mips-unknown-linux-musl,mipsel-unknown-linux-musl,mips64-unknown-linux-muslabi64,mips64el-unknown-linux-muslabi64,arm-unknown-linux-musleabi,arm-unknown-linux-musleabihf,armv5te-unknown-linux-gnueabi,armv5te-unknown-linux-musleabi,armv7-unknown-linux-musleabihf,aarch64-unknown-none,aarch64-unknown-none-softfloat,sparc64-unknown-linux-gnu,x86_64-unknown-redox,thumbv6m-none-eabi,thumbv7m-none-eabi,thumbv7em-none-eabi,thumbv7em-none-eabihf,thumbv8m.base-none-eabi,thumbv8m.main-none-eabi,thumbv8m.main-none-eabihf,riscv32i-unknown-none-elf,riscv32imc-unknown-none-elf,riscv32imac-unknown-none-elf,riscv64imac-unknown-none-elf,riscv64gc-unknown-none-elf,armebv7r-none-eabi,armebv7r-none-eabihf,armv7r-none-eabi,armv7r-none-eabihf,thumbv7neon-unknown-linux-gnueabihf,armv7a-none-eabi
Build completed unsuccessfully in 0:22:57

This was introduced between 0.1.36 and 0.1.38 but I have no idea what's the cause at all.

[bjorn3]

Can you get a backtrace using a debugger?

[Amanieu]

Backtrace:

#0  0x00007fb65cb46631 in llvm::DAGTypeLegalizer::AnalyzeNewNode(llvm::SDNode*) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#1  0x00007fb65cb47067 in llvm::DAGTypeLegalizer::AnalyzeNewValue(llvm::SDValue&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#2  0x00007fb65cb46a9f in llvm::DAGTypeLegalizer::ReplaceValueWith(llvm::SDValue, llvm::SDValue) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#3  0x00007fb65cb2d00e in llvm::DAGTypeLegalizer::ExpandIntegerResult(llvm::SDNode*, unsigned int) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#4  0x00007fb65cb4adfd in llvm::SelectionDAG::LegalizeTypes() () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#5  0x00007fb65cc6b7d4 in llvm::SelectionDAGISel::CodeGenAndEmitDAG() () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#6  0x00007fb65cc6ab77 in llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#7  0x00007fb65cc67926 in llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#8  0x00007fb65c7d078e in llvm::MachineFunctionPass::runOnFunction(llvm::Function&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#9  0x00007fb65c5aafd2 in llvm::FPPassManager::runOnFunction(llvm::Function&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#10 0x00007fb65c5b19e3 in llvm::FPPassManager::runOnModule(llvm::Module&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#11 0x00007fb65c5aba2a in llvm::legacy::PassManagerImpl::run(llvm::Module&) () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-11-rust-1.50.0-nightly.so
#12 0x00007fb66018ed50 in LLVMRustWriteOutputFile () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#13 0x00007fb6600cd77c in rustc_codegen_llvm::back::write::write_output_file () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#14 0x00007fb6600d1f9e in rustc_codegen_llvm::back::write::codegen () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#15 0x00007fb6600b3e2b in rustc_codegen_ssa::back::write::finish_intra_module_work () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#16 0x00007fb6600ae1a3 in rustc_codegen_ssa::back::write::execute_work_item () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#17 0x00007fb65ff9091f in std::sys_common::backtrace::__rust_begin_short_backtrace () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#18 0x00007fb65ff964ad in core::ops::function::FnOnce::call_once{{vtable-shim}} () from /home/amanieu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-4f0cc9f50e53f0ba.so
#19 0x00007fb65f42765a in alloc::boxed::{{impl}}::call_once<(),FnOnce<()>,alloc::alloc::Global> () at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/alloc/src/boxed.rs:1318
#20 alloc::boxed::{{impl}}::call_once<(),alloc::boxed::Box<FnOnce<()>, alloc::alloc::Global>,alloc::alloc::Global> () at /rustc/1c389ffeff814726dec325f0f2b0c99107df2673/library/alloc/src/boxed.rs:1318
#21 std::sys::unix::thread::{{impl}}::new::thread_start () at library/std/src/sys/unix/thread.rs:71
#22 0x00007fb65f3213e9 in start_thread () from /usr/lib/libpthread.so.0
#23 0x00007fb65f23c293 in clone () from /usr/lib/libc.so.6

Bisecting shows that this crash was introduced in b1a7a00.

To reproduce just:

rustup target add aarch64-unknown-none-softfloat
cargo build --target aarch64-unknown-none-softfloat

[AaronKutch]

I wish somebody had pinged me earlier since this was the result of my changes. Here is a reduced example:

#![no_std]

pub fn u128_count_ones(x: u128) -> u32 {
    x.count_ones()
}