Build crtbegin.o/crtend.o from source code by 12101111 · Pull Request #85395 · rust-lang/rust

12101111 · 2021-05-17T03:41:38Z

Build crtbengin.o/crtend.o from source code instead of copying from gcc.

The crtbegin and crtend implementation from llvm don't need crtbeginS.o for PIC. crtbegin{,S,T}.o is unified into one generic crtbegin.o. See the comments in https://reviews.llvm.org/D28791#1419436 and https://reviews.llvm.org/D28791#1420914

fix: #85310 , fix: #47551 , fix: #84033

rust-highfive · 2021-05-17T03:41:41Z

r? @Mark-Simulacrum

(rust-highfive has picked a reviewer for you, use r? to override)

12101111 · 2021-05-19T06:15:20Z

Test with the code from #47551 :

Details

#![feature(backtrace)]#[derive(Clone,Copy)]structFoo{array:[u64;10240],}implFoo{constfnnew() -> Self{Self{array:[0x1122_3344_5566_7788;10240]}}}staticBAR:[Foo;10240] = [Foo::new();10240];fnmain(){let bt = std::backtrace::Backtrace::force_capture();println!("Hello, world! {:?}", bt);println!("{:x}",BAR[0].array[0]);}

The broken rustc that don't link to crtbeginS.o/crtendS.o:

> export RUSTFLAGS="-Z print-link-args -C link-args=-fuse-ld=bfd"
> cargo +stage2 run -vvv
Compiling hello v0.1.0 (/tmp/hello)
Running `CARGO=/home/han/.rustup/toolchains/nightly-x86_64-unknown-linux-musl/bin/cargo CARGO_BIN_NAME=hello CARGO_CRATE_NAME=hello CARGO_MANIFEST_DIR=/tmp/hello CARGO_PKG_AUTHORS='' CARGO_PKG_DESCRIPTION='' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=hello CARGO_PKG_REPOSITORY='' CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' CARGO_PRIMARY_PACKAGE=1 LD_LIBRARY_PATH='/usr/obj/rust/debug/deps:/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib:/home/han/.rustup/toolchains/stage2/lib' rustc --crate-name hello --edition=2018 src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 -C metadata=45f8637d16581c8f -C extra-filename=-45f8637d16581c8f --out-dir /usr/obj/rust/debug/deps -C incremental=/usr/obj/rust/debug/incremental -L dependency=/usr/obj/rust/debug/deps -Z print-link-args -C link-args=-fuse-ld=bfd`
"cc" "-m64" "-Wl,--eh-frame-hdr" "-Wl,-znoexecstack" "-Wl,--as-needed" "-nostartfiles" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/rcrt1.o" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crti.o" "-L" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib" "-L" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.13c46qjpqqmsvlt7.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.15v6bxaiph9x009s.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.1ink71ppmx2dzs7x.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.1uw2b3f6g5y40ue3.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.266s81kb0ncdbolo.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2eue4xcls65wdpx8.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2p4usy9q2qvnypt6.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2ps5mydlcnk9396a.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2skmjjaikvpkfupm.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.30dz11z0aofnesqr.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3n7b5ehgwrintgct.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3u88p76iye7ms53s.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3wogw5s564ur4fuw.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.52b1zbprkak691s9.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.5a02jqibtvw5j173.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.7ufvqzpplts0u9c.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.cc1no8scl2oh3vx.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.hh14nni9hru6433.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.s3hwstby9sigjq.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.uaspq4z5q2q46ku.rcgu.o" "-o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3xix89bijvttq8xf.rcgu.o" "-Wl,--gc-sections" "-static-pie" "-Wl,-zrelro" "-Wl,-znow" "-nodefaultlibs" "-L" "/usr/obj/rust/debug/deps" "-L" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib" "-Wl,--start-group" "-Wl,-Bstatic" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-09863bbdf407aa03.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-1b63f9f92f3108f4.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libminiz_oxide-32d4417712748336.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libadler-6b51cf8ee6f6a418.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libobject-155010ea90fd90f7.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libaddr2line-e5d9a2520c52002b.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libgimli-cb8f304520dcee08.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd_detect-ecccbd55539888eb.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_demangle-aa6c405eaec4f6eb.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libhashbrown-e36d8e13091d3283.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_std_workspace_alloc-3fa5f334a8a4e7aa.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libunwind-c9316e944fa41c58.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libcfg_if-d2617c158ec95334.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/liblibc-a59daf1420a022a8.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc-eed919ff8c26abfe.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_std_workspace_core-66552530c797bb9f.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libcore-e378844bf95f8386.rlib" "-Wl,--end-group" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libcompiler_builtins-47286ef3f3775665.rlib" "-fuse-ld=bfd" "-Wl,-Bdynamic" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crtn.o"
Finished dev [unoptimized + debuginfo] target(s) in 1.47s
Running `/usr/obj/rust/debug/hello`
zsh: segmentation fault (core dumped) cargo +stage2 run -vvv
> lldb /usr/obj/rust/debug/hello
(lldb) target create "/usr/obj/rust/debug/hello"
Current executable set to '/usr/obj/rust/debug/hello' (x86_64).
(lldb) r
Process 32683 launched: '/usr/obj/rust/debug/hello' (x86_64)
Process 32683 stopped
* thread #1, name = 'hello', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
frame #0: 0x00007fffc5fd2301 hello`libunwind::CFI_Parser<libunwind::LocalAddressSpace>::findFDE(libunwind::LocalAddressSpace&, unsigned long, unsigned long, unsigned long, unsigned long, libunwind::CFI_Parser<libunwind::LocalAddressSpace>::FDE_Info*, libunwind::CFI_Parser<libunwind::LocalAddressSpace>::CIE_Info*) + 97
hello`libunwind::CFI_Parser<libunwind::LocalAddressSpace>::findFDE:
-> 0x7fffc5fd2301 <+97>: movl (%rbp), %ebx
0x7fffc5fd2304 <+100>: leaq 0x4(%rbp), %rsi
0x7fffc5fd2308 <+104>: movq %rsi, 0x38(%rsp)
0x7fffc5fd230d <+109>: cmpq %r14, %rbx
(lldb) bt
error: need to add support for DW_TAG_base_type '()' encoded with DW_ATE = 0x7, bit_size = 0
* thread #1, name = 'hello', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
* frame #0: 0x00007fffc5fd2301 hello`libunwind::CFI_Parser<libunwind::LocalAddressSpace>::findFDE(libunwind::LocalAddressSpace&, unsigned long, unsigned long, unsigned long, unsigned long, libunwind::CFI_Parser<libunwind::LocalAddressSpace>::FDE_Info*, libunwind::CFI_Parser<libunwind::LocalAddressSpace>::CIE_Info*) + 97
frame #1: 0x00007fffc5fd844e hello`libunwind::UnwindCursor<libunwind::LocalAddressSpace, libunwind::Registers_x86_64>::setInfoBasedOnIPRegister(bool) + 350
frame #2: 0x00007fffc5fda7f5 hello`unw_step + 165
frame #3: 0x00007fffc5fcdf3b hello`_Unwind_Backtrace + 107
frame #4: 0x00007fffc5fb073c hello`std::backtrace::Backtrace::create::h99b62ff1676d9f60 + 140
frame #5: 0x00007fffc5fb06a0 hello`std::backtrace::Backtrace::force_capture::h28ea90e80c6b235c + 16
frame #6: 0x00007fffc5fa2e82 hello`hello::main::hc539c34270107337 at main.rs:18:14
frame #7: 0x00007fffc5fa261b hello`core::ops::function::FnOnce::call_once::hf9d16316d26b5a58((null)=(hello`hello::main::hc539c34270107337 at main.rs:17), (null)=<unavailable>) at function.rs:227:5
frame #8: 0x00007fffc5fa1cee hello`std::sys_common::backtrace::__rust_begin_short_backtrace::h6c47d048019b78ff(f=(hello`hello::main::hc539c34270107337 at main.rs:17)) at backtrace.rs:125:18
frame #9: 0x00007fffc5fa1b81 hello`std::rt::lang_start::_$u7b$$u7b$closure$u7d$$u7d$::h65a46410314f2661 at rt.rs:49:18
frame #10: 0x00007fffc5fb6f92 hello`std::rt::lang_start_internal::h74e26f259c28581a + 658
frame #11: 0x00007fffc5fa1b60 hello`std::rt::lang_start::h71b37c822e80bcc1(main=(hello`hello::main::hc539c34270107337 at main.rs:17), argc=1, argv=0x00007fffffffba68) at rt.rs:48:5
frame #12: 0x00007fffc5fa300c hello`main + 28
frame #13: 0x00007fffc5fdac2b hello`libc_start_main_stage2 + 39
frame #14: 0x00007fffc5fa1917 hello`_start + 22

rustc in this PR:

> cargo +stage2 run -vvv
Compiling hello v0.1.0 (/tmp/hello)
Running `CARGO=/home/han/.rustup/toolchains/nightly-x86_64-unknown-linux-musl/bin/cargo CARGO_BIN_NAME=hello CARGO_CRATE_NAME=hello CARGO_MANIFEST_DIR=/tmp/hello CARGO_PKG_AUTHORS='' CARGO_PKG_DESCRIPTION='' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=hello CARGO_PKG_REPOSITORY='' CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' CARGO_PRIMARY_PACKAGE=1 LD_LIBRARY_PATH='/usr/obj/rust/debug/deps:/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib:/home/han/.rustup/toolchains/stage2/lib' rustc --crate-name hello --edition=2018 src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 -C metadata=45f8637d16581c8f -C extra-filename=-45f8637d16581c8f --out-dir /usr/obj/rust/debug/deps -C incremental=/usr/obj/rust/debug/incremental -L dependency=/usr/obj/rust/debug/deps -Z print-link-args -C link-args=-fuse-ld=bfd`
"cc" "-m64" "-Wl,--eh-frame-hdr" "-Wl,-znoexecstack" "-Wl,--as-needed" "-nostartfiles" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/rcrt1.o" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crti.o" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crtbeginS.o" "-L" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib" "-L" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.13c46qjpqqmsvlt7.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.15v6bxaiph9x009s.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.1ink71ppmx2dzs7x.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.1uw2b3f6g5y40ue3.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.266s81kb0ncdbolo.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2eue4xcls65wdpx8.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2p4usy9q2qvnypt6.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2ps5mydlcnk9396a.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.2skmjjaikvpkfupm.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.30dz11z0aofnesqr.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3n7b5ehgwrintgct.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3u88p76iye7ms53s.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3wogw5s564ur4fuw.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.52b1zbprkak691s9.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.5a02jqibtvw5j173.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.7ufvqzpplts0u9c.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.cc1no8scl2oh3vx.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.hh14nni9hru6433.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.s3hwstby9sigjq.rcgu.o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.uaspq4z5q2q46ku.rcgu.o" "-o" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f" "/usr/obj/rust/debug/deps/hello-45f8637d16581c8f.3xix89bijvttq8xf.rcgu.o" "-Wl,--gc-sections" "-static-pie" "-Wl,-zrelro" "-Wl,-znow" "-nodefaultlibs" "-L" "/usr/obj/rust/debug/deps" "-L" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib" "-Wl,--start-group" "-Wl,-Bstatic" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-09863bbdf407aa03.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-1b63f9f92f3108f4.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libminiz_oxide-32d4417712748336.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libadler-6b51cf8ee6f6a418.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libobject-155010ea90fd90f7.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libaddr2line-e5d9a2520c52002b.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libgimli-cb8f304520dcee08.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd_detect-ecccbd55539888eb.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_demangle-aa6c405eaec4f6eb.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libhashbrown-e36d8e13091d3283.rlib" "/home/han/rust
/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_std_workspace_alloc-3fa5f334a8a4e7aa.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libunwind-c9316e944fa41c58.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libcfg_if-d2617c158ec95334.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/liblibc-a59daf1420a022a8.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage
2/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc-eed919ff8c26abfe.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_std_workspace_core-66552530c797bb9f.rlib" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libcore-e378844bf95f8386.rlib" "-Wl,--end-group" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/libcompiler_builtins-47286ef3f3775665.rlib" "-fuse-ld=bfd" "-Wl,-Bdynamic" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crtendS.o" "/home/han/rust/obj/build/x86_64-unknown-linux-musl/stage2/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crtn.o"
Finished dev [unoptimized + debuginfo] target(s) in 7.75s
Running `/usr/obj/rust/debug/hello`
Hello, world! Backtrace [{ fn: "hello::main", file: "./src/main.rs", line: 18 }, { fn: "core::ops::function::FnOnce::call_once", file: "/checkout/library/core/src/ops/function.rs", line: 227 }, { fn: "std::sys_common::backtrace::__rust_begin_short_backtrace", file: "/checkout/library/std/src/sys_common/backtrace.rs", line: 125 }, { fn: "std::rt::lang_start::{{closure}}", file: "/checkout/library/std/src/rt.rs", line: 49 }, { fn: "std::rt::lang_start_internal" }, { fn: "std::rt::lang_start", file: "/checkout/library/std/src/rt.rs", line: 48 }, { fn: "main" }]
1122334455667788

Mark-Simulacrum · 2021-05-26T01:35:58Z

r? @nagisa or @petrochenkov perhaps?

I don't know too much about our crtbegin self-contained objects story, and whether building them ourselves (vs. using the ones in system roots) makes sense.

petrochenkov · 2021-05-26T06:01:23Z

@12101111
Why the previous strategy of copying the objects doesn't work?
#85310 appears to be caused by objects for a wrong target being copied, why objects for the right target cannot be copied instead?

12101111 · 2021-05-26T06:08:52Z

gcc's crtbegin.o/crtend.o is built when gcc bootstrap. Those target use musl-gcc which is a wrapper script, so there is no objects for those target.

And the current copy mechanism don't work well when using clang as C compiler.

petrochenkov · 2021-05-26T06:51:09Z

Those target use musl-gcc which is a wrapper script, so there is no objects for those target.

musl-gcc will use crtbegin/crtend from gcc that it wraps (these objects belong to compiler rather than libc, unlike crti/crtn/etc), so they can be copied from there.

And the current copy mechanism don't work well when using clang as C compiler.

A working clang toolchain will still link these objects from somewhere, so they can be copied from the same place.

12101111 · 2021-05-26T11:41:01Z

musl-gcc will use crtbegin/crtend from gcc that it wraps (these objects belong to compiler rather than libc, unlike crti/crtn/etc), so they can be copied from there.

root@7a1d5318dbef:/build# /musl-armv5te/bin/musl-gcc --target=armv5te-unknown-linux-musleabi -print-file-name=crtbegin.o
arm-linux-gnueabi-gcc: error: unrecognized command line option '--target=armv5te-unknown-linux-musleabi'
/usr/lib/gcc-cross/arm-linux-gnueabi/9/crtbegin.o
root@7a1d5318dbef:/build# /musl-arm/bin/musl-gcc --target=arm-unknown-linux-musleabi -print-file-name=crtbegin.oarm-linux-gnueabi-gcc: error: unrecognized command line option '--target=arm-unknown-linux-musleabi'
/usr/lib/gcc-cross/arm-linux-gnueabi/9/crtbegin.o
root@7a1d5318dbef:/build# /musl-armhf/bin/musl-gcc --target=arm-unknown-linux-musleabihf -print-file-name=crtbegin.oarm-linux-gnueabihf-gcc: error: unrecognized command line option '--target=arm-unknown-linux-musleabihf'
/usr/lib/gcc-cross/arm-linux-gnueabihf/9/crtbegin.o
root@7a1d5318dbef:/build# /musl-armv7hf/bin/musl-gcc --target=armv7-unknown-linux-musleabihf -print-file-name=crtbegin.o
arm-linux-gnueabihf-gcc: error: unrecognized command line option '--target=armv7-unknown-linux-musleabihf'
/usr/lib/gcc-cross/arm-linux-gnueabihf/9/crtbegin.o
root@7a1d5318dbef:/build# readelf -A /usr/lib/gcc-cross/arm-linux-gnueabihf/9/crtbegin.o
Attribute Section: aeabi
File Attributes
Tag_CPU_name: "7-A"
Tag_CPU_arch: v7
Tag_CPU_arch_profile: Application
Tag_ARM_ISA_use: Yes
Tag_THUMB_ISA_use: Thumb-2
Tag_FP_arch: VFPv3-D16
Tag_ABI_PCS_wchar_t: 4
Tag_ABI_FP_denormal: Needed
Tag_ABI_FP_exceptions: Needed
Tag_ABI_FP_number_model: IEEE 754
Tag_ABI_align_needed: 8-byte
Tag_ABI_align_preserved: 8-byte, except leaf SP
Tag_ABI_enum_size: int
Tag_ABI_VFP_args: VFP registers
Tag_ABI_optimization_goals: Aggressive Speed
Tag_CPU_unaligned_access: v6

They are the same file. dist-various-1 builder use the same GCC arm cross compiler for 4 different arm target by setting CFLAGS.

rust/src/ci/docker/host-x86_64/dist-various-1/Dockerfile

Lines 63 to 78 in 1969c2e

RUN env \ 
 CC=arm-linux-gnueabi-gcc CFLAGS="-march=armv5te -marm -mfloat-abi=soft" \ 
 CXX=arm-linux-gnueabi-g++ CXXFLAGS="-march=armv5te -marm -mfloat-abi=soft" \ 
 bash musl.sh armv5te && \ 
 env \ 
 CC=arm-linux-gnueabi-gcc CFLAGS="-march=armv6 -marm" \ 
 CXX=arm-linux-gnueabi-g++ CXXFLAGS="-march=armv6 -marm" \ 
 bash musl.sh arm && \ 
 env \ 
 CC=arm-linux-gnueabihf-gcc CFLAGS="-march=armv6 -marm -mfpu=vfp" \ 
 CXX=arm-linux-gnueabihf-g++ CXXFLAGS="-march=armv6 -marm -mfpu=vfp" \ 
 bash musl.sh armhf && \ 
 env \ 
 CC=arm-linux-gnueabihf-gcc CFLAGS="-march=armv7-a" \ 
 CXX=arm-linux-gnueabihf-g++ CXXFLAGS="-march=armv7-a" \ 
 bash musl.sh armv7hf && \ 

A working clang toolchain will still link these objects from somewhere, so they can be copied from the same place.

Clang don't provided a command line to get the location of compiler-rt. And compiler-rt is optional for clang.

https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/failed.20to.20bootstrap/near/237962952

nagisa · 2021-05-26T14:11:40Z

r? @petrochenkov

mati865 · 2021-05-26T16:06:05Z

Clang don't provided a command line to get the location of compiler-rt.

It does:

# This mingw-w64 toolchain uses compiler-rt by the default
$ /clang64/bin/clang -print-libgcc-file-name
D:/msys64/clang64/lib/clang/12.0.0/lib/windows/libclang_rt.builtins-x86_64.a
# This mingw-w64 toolchain uses libgcc by the default
$ /mingw64/bin/clang -print-libgcc-file-name
D:/msys64/mingw64/lib/gcc/x86_64-w64-mingw32/10.3.0/libgcc.a
$ /mingw64/bin/clang -print-libgcc-file-name -rtlib=compiler-rt
D:/msys64/mingw64/lib/clang/12.0.0/lib/windows/libclang_rt.builtins-x86_64.a

12101111 · 2021-05-26T16:55:41Z

This is intrinsics, not crtbegin.o/crtend.o. The logic in clang is at
https://github.com/llvm/llvm-project/blob/d28af7c654d8db0b68c175db5ce212d74fb5e9bc/clang/lib/Driver/Driver.cpp#L1829, and the source code shows there is no such option that print TC.getCompilerRT(C.getArgs(), "crtbegin");

A full clang installation should have crtbegin.o in /usr/lib/clang/12.0.0/lib/linux/clang_rt.crtbegin-x86_64.o.
But on my system ( Gentoo Linux ), compiler-rt is optional for clang, so this file may not exsit.
Alpine also don't list compiler-rt as dependence of clang : https://pkgs.alpinelinux.org/package/edge/main/x86/compiler-rt

petrochenkov · 2021-05-29T17:30:31Z

But on my system ( Gentoo Linux ), compiler-rt is optional for clang, so this file may not exsit.

The files must always exist somewhere, otherwise the C toolchain will be non-functional.
Clang takes gcc's objects if it doesn't ship its own.

My main question is what is simpler, less error-prone and requires less support - implementing the object search for all platforms on which x.py dist is supposed to be run, or building the objects ourselves (with correct flags and defines).

petrochenkov · 2021-05-29T17:37:52Z

This PR will need a backport to beta and stable (if one more dot release is produced), because #82534 landed exactly on the current stable.
Alternatively, a revert of #82534 can be backported (assuming that not linking crtbegin/end at all is better than linking incorrect objects).

petrochenkov · 2021-05-29T17:40:39Z

@12101111
Could you add a test making sure that mixed C/Rust code linked by rustc and using some features requiring crtbegin/end (e.g. init fini arrays) works as expected?

petrochenkov · 2021-05-30T18:58:12Z

@bors r+

bors · 2021-05-30T18:58:14Z

📌 Commit 5b44522ff115b8a2ac82217c6a69233988aae84e has been approved by petrochenkov

bors · 2021-05-30T22:48:11Z

⌛ Testing commit 5b44522ff115b8a2ac82217c6a69233988aae84e with merge 5168f9db7cf61a646190550e7fd0c1165898ca49...

petrochenkov · 2021-05-31T06:00:29Z

@bors r+

bors · 2021-05-31T06:00:30Z

📌 Commit 61c1155 has been approved by petrochenkov

bors · 2021-05-31T07:32:55Z

⌛ Testing commit 61c1155 with merge 7baa7af...

bors · 2021-05-31T10:13:40Z

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 7baa7af to master...

apiraino · 2021-06-04T09:30:18Z

Beta backport accepted as per compiler team on Zulip

Stable backport declined (discussion on Zulip) since in 2 weeks from now it will land anyway on 1.53

@rustbot label +beta-accepted -stable-nominated

…ulacrum [beta] backports * Disable the machine outliner by default rust-lang#86020 * Fix incorrect gating of nonterminals in key-value attributes rust-lang#85445 * Build crtbegin.o/crtend.o from source code rust-lang#85395 * Bring back x86_64-sun-solaris target to rustup rust-lang#85252 * Preserve SyntaxContext for invalid/dummy spans in crate metadata rust-lang#85211 * [beta] backport: Remove unsound TrustedRandomAccess implementations rust-lang#86222 r? `@Mark-Simulacrum`

rust-highfive assigned Mark-Simulacrum May 17, 2021

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12101111 force-pushed the build-crt branch from b044770 to 5f03f6dCompare May 19, 2021 06:02

12101111 changed the title ~~Build crtbengin.o/crtend.o from source code~~Build crtbegin.o/crtend.o from source codeMay 19, 2021

12101111 force-pushed the build-crt branch from 5f03f6d to a27aaa3Compare May 22, 2021 15:50

12101111 mentioned this pull request May 23, 2021
build llvm libunwind.a in rustbuild #85600
Merged

rust-highfive assigned nagisa and unassigned Mark-Simulacrum May 26, 2021

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Build crtbengin.o/crtend.o from source code
61c1155

12101111 force-pushed the build-crt branch from 5b44522 to 61c1155Compare May 31, 2021 03:12

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bors merged commit 7baa7af into rust-lang:masterMay 31, 2021

rustbot added this to the 1.54.0 milestone May 31, 2021

rustbot added beta-accepted Accepted for backporting to the compiler in the beta channel. and removed stable-nominated Nominated for backporting to the compiler in the stable channel. labels Jun 4, 2021

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[beta] backports #86225
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