[llvm-dev] llvm::UpgradeDebugInfo does a full verification

Adrian Prantl via llvm-dev llvm-dev at lists.llvm.org
Wed Jan 24 09:26:56 PST 2018

> On Jan 23, 2018, at 11:01 PM, Carlo Kok via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> Hi,
> I noticed that since recently UpgradeDebugInfo (Which is called for loading any bitcode from disk/memory) does a full bitcode verification. Is this on purpose or is this a mistake? Seems to have a fair amount of overhead.

That is be design, though there are bugs in the LTO pipeline where we run the Verifier more than once. "Upgrading" debug info means checking for a malformed metadata graph (for example, produced by older, buggy versions of LLVM, or buggy frontends) that would crash LLVM. The "upgrade" consists of stripping the debug info form the module.

-- adrian

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