Closed
Description
openedon Sep 3, 2018
This example (reduced from rustc_codegen_llvm) either crashes LLVM or makes it emit an assertion:
fn dummy() {}
mod llvm {
pub(crate) struct Foo;
}
mod foo {
pub(crate) struct Foo<T>(T);
impl Foo<::llvm::Foo> {
pub(crate) fn foo() {
for _ in 0..0 {
for _ in &[::dummy()] {
::dummy();
::dummy();
::dummy();
}
}
}
}
pub(crate) fn foo() {
Foo::foo();
Foo::foo();
}
}
pub fn foo() {
foo::foo();
}I suspect the for loops aren't needed, but the control-flow there affects the bug in finicky ways.
The llvm name of the module appears to be important and tied to the fact that we end up emitting llvm:: in a symbol name (because of the impl), which gets mangled as llvm.. (note the two dots).
Among other things, changing the . we use to mangle :, to $ makes the bug go away.
Assertion message (if LLVM assertions are enabled):
rustc: /checkout/src/llvm/lib/Transforms/IPO/FunctionImport.cpp:961:
auto llvm::thinLTOInternalizeModule(llvm::Module &, const llvm::GVSummaryMapTy &)::(anonymous class)::operator()(const llvm::GlobalValue &) const:
Assertion `GS != DefinedGlobals.end()' failed.Stack backtrace for SIGSEGV (if LLVM assertions are disabled):
#0 0x00007fffed5240d2 in std::_Function_handler<bool (llvm::GlobalValue const&), llvm::thinLTOInternalizeModule(llvm::Module&, llvm::DenseMap<unsigned long, llvm::GlobalValueSummary*, llvm::DenseMapInfo<unsigned long>, llvm::detail::DenseMapPair<unsigned long, llvm::GlobalValueSummary*> > const&)::$_2>::_M_invoke(std::_Any_data const&, llvm::GlobalValue const&) ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
#1 0x00007fffed5409be in llvm::InternalizePass::maybeInternalize(llvm::GlobalValue&, std::set<llvm::Comdat const*, std::less<llvm::Comdat const*>, std::allocator<llvm::Comdat const*> > const&) ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
#2 0x00007fffed540e26 in llvm::InternalizePass::internalizeModule(llvm::Module&, llvm::CallGraph*) ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
#3 0x00007fffed520079 in llvm::thinLTOInternalizeModule(llvm::Module&, llvm::DenseMap<unsigned long, llvm::GlobalValueSummary*, llvm::DenseMapInfo<unsigned long>, llvm::detail::DenseMapPair<unsigned long, llvm::GlobalValueSummary*> > const&) ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
#4 0x00007fffecda34f8 in LLVMRustPrepareThinLTOInternalize ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
#5 0x00007fffeccb1a2c in rustc_codegen_llvm::back::lto::LtoModuleCodegen::optimize ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
#6 0x00007fffecc5fbb2 in rustc_codegen_llvm::back::write::execute_work_item ()
from /home/eddy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.soSign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Metadata
Assignees
Labels
Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.Category: This is a bug.Category: This is a bug.Issue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics.Issue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics.Relevant to the compiler team, which will review and decide on the PR/issue.Relevant to the compiler team, which will review and decide on the PR/issue.