Clang ICE: 'Align can't be zero' with large number passed to `ext_vector_type` attribute

Question

Clang ICE: 'Align can't be zero' with large number passed to `ext_vector_type` attribute

langston-barrett opened this issue 2 years ago · 2 comments

This bug was found with a fuzzer; please feel free to close if it's not helpful.

typedef float t __attribute__((ext_vector_type(0xfffffff)));
struct s {
  t position;
};
struct s x = {0};

Godbolt

clang++: /root/llvm-project/llvm/include/llvm/Support/MathExtras.h:486: uint64_t llvm::alignTo(uint64_t, uint64_t): Assertion `Align != 0u && "Align can't be 0."' failed.
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 -c -O0 <source>
1.	<source>:5:17: current parser token ';'
 #0 0x000055ebb681449f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x401f49f)
 #1 0x000055ebb68121dc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x401d1dc)
 #2 0x000055ebb675f2f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f1a5afb3420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f1a5aa8000b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f1a5aa5f859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f1a5aa5f729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f1a5aa70fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x000055ebba1d44c5 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x79df4c5)
 #9 0x000055ebba1e0668 (anonymous namespace)::ItaniumRecordLayoutBuilder::LayoutField(clang::FieldDecl const*, bool) RecordLayoutBuilder.cpp:0:0
#10 0x000055ebba1e1d4f (anonymous namespace)::ItaniumRecordLayoutBuilder::LayoutFields(clang::RecordDecl const*) RecordLayoutBuilder.cpp:0:0
#11 0x000055ebba1deb00 clang::ASTContext::getASTRecordLayout(clang::RecordDecl const*) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x79e9b00)
#12 0x000055ebba021ff0 (anonymous namespace)::RecordExprEvaluator::VisitCXXParenListOrInitListExpr(clang::Expr const*, llvm::ArrayRef<clang::Expr*>) ExprConstant.cpp:0:0
#13 0x000055ebba0553d2 clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::RecordExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
#14 0x000055ebba055ee4 EvaluateRecord(clang::Expr const*, (anonymous namespace)::LValue const&, clang::APValue&, (anonymous namespace)::EvalInfo&) ExprConstant.cpp:0:0
#15 0x000055ebba020125 EvaluateInPlace(clang::APValue&, (anonymous namespace)::EvalInfo&, (anonymous namespace)::LValue const&, clang::Expr const*, bool) ExprConstant.cpp:0:0
#16 0x000055ebba05a839 clang::Expr::EvaluateAsInitializer(clang::APValue&, clang::ASTContext const&, clang::VarDecl const*, llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7865839)
#17 0x000055ebb9f2d7c2 clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x77387c2)
#18 0x000055ebb9f2dba9 clang::VarDecl::checkForConstantInitialization(llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7738ba9)
#19 0x000055ebb9243a45 clang::Sema::CheckCompleteVariableDeclaration(clang::VarDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a4ea45)
#20 0x000055ebb9258d2a clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a63d2a)
#21 0x000055ebb8f1f28e clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x672a28e)
#22 0x000055ebb8f30818 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x673b818)
#23 0x000055ebb8ef8eb2 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6703eb2)
#24 0x000055ebb8ef976f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#25 0x000055ebb8f001f9 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x670b1f9)
#26 0x000055ebb8f00b4d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x670bb4d)
#27 0x000055ebb8ef4a1a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66ffa1a)
#28 0x000055ebb7a34268 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x523f268)
#29 0x000055ebb7298f09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4aa3f09)
#30 0x000055ebb721d436 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4a28436)
#31 0x000055ebb737cbf7 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b87bf7)
#32 0x000055ebb3d995f6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x15a45f6)
#33 0x000055ebb3d9541a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#34 0x000055ebb708619d 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
#35 0x000055ebb675f7e0 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f6a7e0)
#36 0x000055ebb7086a5f 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
#37 0x000055ebb704e29c clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x485929c)
#38 0x000055ebb704ed3d 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+++0x4859d3d)
#39 0x000055ebb70569ed clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48619ed)
#40 0x000055ebb3d97aa0 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x15a2aa0)
#41 0x000055ebb3ca34d5 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x14ae4d5)
#42 0x00007f1a5aa61083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#43 0x000055ebb3d9012e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x159b12e)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

Answer 1 · 2023-03-28T00:43:41.000Z

@llvm/issue-subscribers-clang-frontend

Answer 2 · 2023-03-28T01:06:44.000Z

It looks like there are multiple crash bugs associated with this feature (clearly not good enough coverage) if we use __attribute__((ext_vector_type(0x0004ffff))) instead: https://godbolt.org/z/EoP4PxjP4 we obtain a different assert based on bitwidth:

clang++: /root/llvm-project/llvm/lib/IR/Type.cpp:333:
static llvm::IntegerType* llvm::IntegerType::get(llvm::LLVMContext&, unsigned int):
Assertion `NumBits <= MAX_INT_BITS && "bitwidth too large"' failed.

We should be issues diagnostics instead of crashing.