Intermitent bug in CIRGenException.cpp

[bcardosolopes]

Lots of testing jobs are failing with this error when running CIR/CodeGen/global-new.cpp:

NYI
UNREACHABLE executed at /__w/clangir/clangir/clang/lib/CIR/CodeGen/CIRGenException.cpp:842!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.

I haven't been able to repro yet, but looks like it's due to some uninitialized data or missing target dependency, given that we have the targets in question do not use funclets:

  if (Personality.usesFuncletPads()) {
    // We don't need separate landing pads in the funclet model.
    llvm_unreachable("NYI");
  } 

[bcardosolopes]

Investigating a solution

[bcardosolopes]

It reproduces on release builds for me consistently on Linux, I cannot get debug builds to repro yet tho.

[smeenai]

The failure I'm seeing in global-new.cpp with UBSan is:

/home/smeenai/clangir/clang/lib/CIR/CodeGen/CIRGenCall.cpp:460:33: runtime error: member call on null pointer of type 'cir::CIRGenFunction::LexicalScope'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/smeenai/clangir/clang/lib/CIR/CodeGen/CIRGenCall.cpp:460:33

That's the following code:

clangir/clang/lib/CIR/CodeGen/CIRGenCall.cpp

Line 460 in cef3459

auto op = CGF.currLexScope->getClosestTryParent();

It's triggered by the following bit of code in the test:

struct e { e(int); };
e *g = new e(0);

The obvious fix would be a null check for currLexScope, but I'm not sure if it's expected to be null here (i.e. if there's supposed to be a lexical scope created for globals or not).

[bcardosolopes]

Thanks for finding the root cause, I know a good fix for this, will push something soon!