Segfault when using llvm_asm memory constraint #87612
Description
I tried this code:
#![feature(llvm_asm)] #![crate_type="staticlib"] // using no_mangle to force codegen, otherwise nothing is emitted #[no_mangle] pub unsafe fn test() -> u32 { let test: u32; llvm_asm!("mov $$32, $0" : "=m"(test)); test }I expected to see this happen:
> rustc test.rs <no output> Instead, this happened:
> rustc test.rs /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x4fdb63)[0x7f6a182c2b63] /lib/x86_64-linux-gnu/libpthread.so.0(+0x153c0)[0x7f6a17a1f3c0] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm19SelectionDAGBuilder14visitInlineAsmERKNS_8CallBaseE+0x1621)[0x7f6a14f71c31] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm19SelectionDAGBuilder5visitERKNS_11InstructionE+0x67)[0x7f6a14f4ff07] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm16SelectionDAGISel16SelectBasicBlockENS_14ilist_iteratorINS_12ilist_detail12node_optionsINS_11InstructionELb0ELb0EvEELb0ELb1EEES6_Rb+0x12e)[0x7f6a1500f3be] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm16SelectionDAGISel20SelectAllBasicBlocksERKNS_8FunctionE+0x1a3b)[0x7f6a1500e49b] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm16SelectionDAGISel20runOnMachineFunctionERNS_15MachineFunctionE+0xb1d)[0x7f6a1500ba9d] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(+0x48c1177)[0x7f6a16f13177] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm19MachineFunctionPass13runOnFunctionERNS_8FunctionE+0xee)[0x7f6a14b3496e] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm13FPPassManager13runOnFunctionERNS_8FunctionE+0x639)[0x7f6a148f7869] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm13FPPassManager11runOnModuleERNS_6ModuleE+0x33)[0x7f6a148fe703] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm6legacy15PassManagerImpl3runERNS_6ModuleE+0x470)[0x7f6a148f80d0] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x20c41e8)[0x7f6a19e891e8] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x2050c3f)[0x7f6a19e15c3f] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x2053afc)[0x7f6a19e18afc] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x204f29b)[0x7f6a19e1429b] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x2048ada)[0x7f6a19e0dada] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x20940bc)[0x7f6a19e590bc] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x20b267c)[0x7f6a19e7767c] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/libstd-9c44f1fe63de3edb.so(rust_metadata_std_ed022288c3a1d27e+0xa8a97)[0x7f6a17aeda97] /lib/x86_64-linux-gnu/libpthread.so.0(+0x9609)[0x7f6a17a13609] /lib/x86_64-linux-gnu/libc.so.6(clone+0x43)[0x7f6a17927293] Segmentation fault Meta
rustc --version --verbose:
rustc 1.56.0-nightly (492723897 2021-07-29) binary: rustc commit-hash: 492723897e9b4db6701b3a75b72618d08a7d5319 commit-date: 2021-07-29 host: x86_64-unknown-linux-gnu release: 1.56.0-nightly LLVM version: 12.0.1 Backtrace
> BACKTRACE=1 rustc test.rs /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x4fdb63)[0x7f6d10697b63] /lib/x86_64-linux-gnu/libpthread.so.0(+0x153c0)[0x7f6d0fdf43c0] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm19SelectionDAGBuilder14visitInlineAsmERKNS_8CallBaseE+0x1621)[0x7f6d0d346c31] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm19SelectionDAGBuilder5visitERKNS_11InstructionE+0x67)[0x7f6d0d324f07] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm16SelectionDAGISel16SelectBasicBlockENS_14ilist_iteratorINS_12ilist_detail12node_optionsINS_11InstructionELb0ELb0EvEELb0ELb1EEES6_Rb+0x12e)[0x7f6d0d3e43be] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm16SelectionDAGISel20SelectAllBasicBlocksERKNS_8FunctionE+0x1a3b)[0x7f6d0d3e349b] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm16SelectionDAGISel20runOnMachineFunctionERNS_15MachineFunctionE+0xb1d)[0x7f6d0d3e0a9d] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(+0x48c1177)[0x7f6d0f2e8177] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm19MachineFunctionPass13runOnFunctionERNS_8FunctionE+0xee)[0x7f6d0cf0996e] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm13FPPassManager13runOnFunctionERNS_8FunctionE+0x639)[0x7f6d0cccc869] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm13FPPassManager11runOnModuleERNS_6ModuleE+0x33)[0x7f6d0ccd3703] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so(_ZN4llvm6legacy15PassManagerImpl3runERNS_6ModuleE+0x470)[0x7f6d0cccd0d0] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x20c41e8)[0x7f6d1225e1e8] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x2050c3f)[0x7f6d121eac3f] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x2053afc)[0x7f6d121edafc] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x204f29b)[0x7f6d121e929b] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x2048ada)[0x7f6d121e2ada] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x20940bc)[0x7f6d1222e0bc] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so(+0x20b267c)[0x7f6d1224c67c] /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/libstd-9c44f1fe63de3edb.so(rust_metadata_std_ed022288c3a1d27e+0xa8a97)[0x7f6d0fec2a97] /lib/x86_64-linux-gnu/libpthread.so.0(+0x9609)[0x7f6d0fde8609] /lib/x86_64-linux-gnu/libc.so.6(clone+0x43)[0x7f6d0fcfc293] Segmentation fault GDB Backtrace
Reading symbols from rustc... (gdb) run test.rs Starting program: /home/tuomas/.cargo/bin/rustc test.rs [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". process 12241 is executing new program: /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [New Thread 0x7fffee3ff700 (LWP 12245)] [New Thread 0x7fffe8387700 (LWP 12246)] [New Thread 0x7fffe7dff700 (LWP 12247)] [New Thread 0x7fffe73ff700 (LWP 12248)] [New Thread 0x7fffe6dff700 (LWP 12249)] Thread 6 "opt test.6a6880" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fffe6dff700 (LWP 12249)] 0x00007ffff1809c31 in llvm::SelectionDAGBuilder::visitInlineAsm(llvm::CallBase const&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so (gdb) bt #0 0x00007ffff1809c31 in llvm::SelectionDAGBuilder::visitInlineAsm(llvm::CallBase const&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #1 0x00007ffff17e7f07 in llvm::SelectionDAGBuilder::visit(llvm::Instruction const&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #2 0x00007ffff18a73be in llvm::SelectionDAGISel::SelectBasicBlock(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction, false, false, void>, false, true>, llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction, false, false, void>, false, true>, bool&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #3 0x00007ffff18a649b in llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #4 0x00007ffff18a3a9d in llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #5 0x00007ffff37ab177 in (anonymous namespace)::X86DAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&) [clone .llvm.6640036156556231831] () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #6 0x00007ffff13cc96e in llvm::MachineFunctionPass::runOnFunction(llvm::Function&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #7 0x00007ffff118f869 in llvm::FPPassManager::runOnFunction(llvm::Function&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #8 0x00007ffff1196703 in llvm::FPPassManager::runOnModule(llvm::Module&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightl--Type <RET> for more, q to quit, c to continue without paging-- y.so #9 0x00007ffff11900d0 in llvm::legacy::PassManagerImpl::run(llvm::Module&) () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/../lib/libLLVM-12-rust-1.56.0-nightly.so #10 0x00007ffff67211e8 in LLVMRustWriteOutputFile () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #11 0x00007ffff66adc3f in rustc_codegen_llvm::back::write::write_output_file () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #12 0x00007ffff66b0afc in rustc_codegen_llvm::back::write::codegen () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #13 0x00007ffff66ac29b in rustc_codegen_ssa::back::write::finish_intra_module_work () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #14 0x00007ffff66a5ada in rustc_codegen_ssa::back::write::execute_work_item () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #15 0x00007ffff66f10bc in std::sys_common::backtrace::__rust_begin_short_backtrace () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #16 0x00007ffff670f67c in core::ops::function::FnOnce::call_once{{vtable-shim}} () from /home/tuomas/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-41fdbb8b89e55544.so #17 0x00007ffff4385a97 in <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once () at /rustc/492723897e9b4db6701b3a75b72618d08a7d5319/library/alloc/src/boxed.rs:1572 #18 <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once () at /rustc/492723897e9b4db6701b3a75b72618d08a7d5319/library/alloc/src/boxed.rs:1572 #19 std::sys::unix::thread::Thread::new::thread_start () at library/std/src/sys/unix/thread.rs:91 #20 0x00007ffff42ab609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #21 0x00007ffff41bf293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95