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Default comparision operator + zero-sized bit field cause crash in Clang 14 / 15 #61417

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ppavel96 opened this issue Mar 14, 2023 · 6 comments
Closed

Default comparision operator + zero-sized bit field cause crash in Clang 14 / 15 #61417

ppavel96 opened this issue Mar 14, 2023 · 6 comments
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clang:frontend Language frontend issues, e.g. anything involving "Sema" confirmed Verified by a second party crash-on-valid

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@ppavel96
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ppavel96 commented Mar 14, 2023 •
edited by shafik
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Sample code: https://godbolt.org/z/bW71vGW1G

#include <iostream>

class Test {
private:
    unsigned A_: 1;
    unsigned   : 0;

public:
    inline Test()
        : A_(0)
    {
    }

    bool operator==(const Test& rhs) const noexcept = default;
};

int main() {
    Test a, b;
    std::cout << unsigned(a == b) << '\n';
}

Versions prior to 14 do not crash but result is incorrect (and it does not look to me like something that should cause undefined behaviour)
@shafik
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shafik commented Mar 14, 2023

Confirmed: https://godbolt.org/z/EYxY5EnG1

Assertion:

clang++: /root/llvm-project/clang/lib/CodeGen/CGRecordLayout.h:227:
const clang::CodeGen::CGBitFieldInfo& clang::CodeGen::CGRecordLayout::getBitFieldInfo(const clang::FieldDecl*) const: 
Assertion `it != BitFields.end() && "Unable to find bitfield info"' failed.

Backtrace:

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -O3 -std=c++20 <source>
1.	<eof> parser at end of file
2.	Per-file LLVM IR generation
3.	<source>:14:10: Generating code for declaration 'Test::operator=='
 #0 0x0000559323b7b90f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x403890f)
 #1 0x0000559323b7964c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x403664c)
 #2 0x0000559323ac6cd8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007fb5b932f420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007fb5b8dfc00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007fb5b8ddb859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007fb5b8ddb729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007fb5b8decfd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x000055932422db65 clang::CodeGen::CGRecordLayout::getBitFieldInfo(clang::FieldDecl const*) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46eab65)
 #9 0x000055932423d434 clang::CodeGen::CodeGenFunction::EmitLValueForField(clang::CodeGen::LValue, clang::FieldDecl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46fa434)
#10 0x00005593242545af clang::CodeGen::CodeGenFunction::EmitMemberExpr(clang::MemberExpr const*) (.part.0) CGExpr.cpp:0:0
#11 0x00005593242556d6 clang::CodeGen::CodeGenFunction::EmitMemberExpr(clang::MemberExpr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47126d6)
#12 0x0000559324248e78 clang::CodeGen::CodeGenFunction::EmitLValueHelper(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4705e78)
#13 0x0000559324254092 clang::CodeGen::CodeGenFunction::EmitCheckedLValue(clang::Expr const*, clang::CodeGen::CodeGenFunction::TypeCheckKind) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4711092)
#14 0x000055932429ff03 (anonymous namespace)::ScalarExprEmitter::EmitLoadOfLValue(clang::Expr const*) CGExprScalar.cpp:0:0
#15 0x00005593242a01b2 (anonymous namespace)::ScalarExprEmitter::VisitMemberExpr(clang::MemberExpr*) CGExprScalar.cpp:0:0
#16 0x0000559324297f66 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#17 0x00005593242993fb (anonymous namespace)::ScalarExprEmitter::Visit(clang::Expr*) CGExprScalar.cpp:0:0
#18 0x000055932429bcfb (anonymous namespace)::ScalarExprEmitter::VisitCastExpr(clang::CastExpr*) CGExprScalar.cpp:0:0
#19 0x000055932429809d clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#20 0x00005593242993fb (anonymous namespace)::ScalarExprEmitter::Visit(clang::Expr*) CGExprScalar.cpp:0:0
#21 0x000055932429b90e (anonymous namespace)::ScalarExprEmitter::VisitCastExpr(clang::CastExpr*) CGExprScalar.cpp:0:0
#22 0x000055932429809d clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#23 0x00005593242a3446 clang::CodeGen::CodeGenFunction::EmitPromotedScalarExpr(clang::Expr const*, clang::QualType) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4760446)
#24 0x00005593242a4076 (anonymous namespace)::ScalarExprEmitter::EmitBinOps(clang::BinaryOperator const*, clang::QualType) CGExprScalar.cpp:0:0
#25 0x00005593242a4788 (anonymous namespace)::ScalarExprEmitter::EmitCompare(clang::BinaryOperator const*, llvm::CmpInst::Predicate, llvm::CmpInst::Predicate, llvm::CmpInst::Predicate, bool) CGExprScalar.cpp:0:0
#26 0x000055932429874e clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#27 0x000055932429f884 clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x475c884)
#28 0x000055932422e8ed clang::CodeGen::CodeGenFunction::EvaluateExprAsBool(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46eb8ed)
#29 0x00005593242999a4 (anonymous namespace)::ScalarExprEmitter::VisitBinLAnd(clang::BinaryOperator const*) CGExprScalar.cpp:0:0
#30 0x000055932429849b clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#31 0x000055932429f884 clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x475c884)
#32 0x0000559323ea0b64 clang::CodeGen::CodeGenFunction::EmitReturnStmt(clang::ReturnStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x435db64)
#33 0x0000559323ea819b clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x436519b)
#34 0x0000559323eaeca4 clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x436bca4)
#35 0x0000559323f0f36a clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43cc36a)
#36 0x0000559323f2257b clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43df57b)
#37 0x0000559323f84d99 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4441d99)
#38 0x0000559323f7fd65 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x443cd65)
#39 0x0000559323f8ad26 clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4447d26)
#40 0x0000559323f8d7b0 clang::CodeGen::CodeGenModule::Release() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x444a7b0)
#41 0x0000559324daaf4a (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) ModuleBuilder.cpp:0:0
#42 0x0000559324da9735 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5266735)
#43 0x0000559326239599 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66f6599)
#44 0x0000559324da8688 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5265688)
#45 0x000055932460f999 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4acc999)
#46 0x0000559324593bb6 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4a50bb6)
#47 0x00005593246f35e7 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4bb05e7)
#48 0x00005593210bd976 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x157a976)
#49 0x00005593210b979a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#50 0x00005593243fa1bd void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#51 0x0000559323ac71c0 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f841c0)
#52 0x00005593243faa7f clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#53 0x00005593243c1d2c clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x487ed2c)
#54 0x00005593243c27cd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x487f7cd)
#55 0x00005593243ca56d clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x488756d)
#56 0x00005593210bbe20 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x1578e20)
#57 0x0000559320fc8405 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x1485405)
#58 0x00007fb5b8ddd083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#59 0x00005593210b44de _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x15714de)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

@shafik
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shafik commented Mar 14, 2023

I wonder if this is related to: #61335

@shafik shafik added confirmed Verified by a second party crash-on-valid and removed new issue labels Mar 14, 2023
@EugeneZelenko EugeneZelenko added the clang:codegen IR generation bugs: mangling, exceptions, etc. label Mar 14, 2023
@llvmbot
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llvmbot commented Mar 14, 2023

@llvm/issue-subscribers-clang-codegen

@shafik
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shafik commented Mar 17, 2023

Funny enough this fails: https://godbolt.org/z/4hPeboMhb

struct A {
    unsigned x : 1;
    unsigned   : 0;

    constexpr A() : x(0) {}
    bool operator==(const A& rhs) const noexcept = default;
};

void f() {
    constexpr A a, b;
    constexpr bool c = (a == b);
}

Because it detects the out of lifetime read of the unnamed bit-field.

@shafik
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shafik commented Mar 17, 2023

PR: https://reviews.llvm.org/D146329

shafik added a commit that referenced this issue Apr 14, 2023
@shafik
[Clang] Fix defaulted equality operator so that it does not attempt t…
6d0fab4 
…o compare unnamed bit-fields

If we look at class.bit p2 it tells us that that unnamed bit-fields are not
members and class.compare.default p5 tells us that we should only compare
non-static data members of the class.

This fixes: #61335 and #61417

Differential Revision: https://reviews.llvm.org/D146329
@shafik shafik closed this as completed May 4, 2023
@EugeneZelenko EugeneZelenko added clang:frontend Language frontend issues, e.g. anything involving "Sema" and removed clang:codegen IR generation bugs: mangling, exceptions, etc. labels May 4, 2023
@llvmbot
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llvmbot commented May 4, 2023

@llvm/issue-subscribers-clang-frontend

flemairen6 pushed a commit to Xilinx/llvm-project that referenced this issue May 10, 2023
@shafik
[Clang] Fix defaulted equality operator so that it does not attempt t…
de04cee 
…o compare unnamed bit-fields

If we look at class.bit p2 it tells us that that unnamed bit-fields are not
members and class.compare.default p5 tells us that we should only compare
non-static data members of the class.

This fixes: llvm#61335 and llvm#61417

Differential Revision: https://reviews.llvm.org/D146329
veselypeta pushed a commit to veselypeta/cherillvm that referenced this issue Aug 21, 2024
@shafik @veselypeta
[Clang] Fix defaulted equality operator so that it does not attempt t…
e69cd6c 
…o compare unnamed bit-fields

If we look at class.bit p2 it tells us that that unnamed bit-fields are not
members and class.compare.default p5 tells us that we should only compare
non-static data members of the class.

This fixes: llvm/llvm-project#61335 and llvm/llvm-project#61417

Differential Revision: https://reviews.llvm.org/D146329
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