llvm/llvm-project

crash when section has `.cfi_startproc` but no `.cfi_endproc`

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#177,852 建立於 2026年1月25日

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crashgood first issuellvm:mc

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描述

LLVM crashes on this program

https://godbolt.org/z/9W51vc3bW

module asm ".pushsection .text.foo,\22ax\22, @progbits"
module asm ".type foo, @function"
module asm "foo:"
module asm ".cfi_startproc"
module asm ".popsection"

module asm ".type bar, @function"
module asm "bar:"
module asm ".cfi_startproc"
module asm ".cfi_endproc"

llc: /root/llvm-project/llvm/lib/MC/MCExpr.cpp:223: llvm::MCSymbolRefExpr::MCSymbolRefExpr(const llvm::MCSymbol*, llvm::MCExpr::Spec, const llvm::MCAsmInfo*, llvm::SMLoc): Assertion `Symbol' failed.

This assembly is malformed (but in a way that might come up during development). When the .popsection is removed, we actually get a nice error:

<inline asm>:8:1: error: starting new .cfi frame before finishing the previous one
.cfi_endproc
^
Compiler returned: 1

I think that .popsection should emit an error when the section opened a CFI scope that wasn't yet closed.

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研究方向
Investigate the assembly parsing code, likely in llvm/lib/MC/MCParser/AsmParser.cpp or MCStreamer.cpp, to understand how .cfi startproc and .cfi endproc directives are tracked. The issue suggests that .popsection should emit an error when a CFI scope is left open. Look for where section push/pop operations are handled and add a check for pending CFI frames before allowing a section pop. The existing error message 'starting new .cfi frame before finishing the previous one' indicates the tracking mechanism exists; extend it to .popsection.
技術棧
cpp
領域
tooling
議題類型
錯誤
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3
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活躍
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清晰
前置要求
understanding of CFI directivesfamiliarity with LLVM MC layer
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
40