Backport: [BPF] Fix BitCast Assertion with NonZero AddrSpace #130995
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eddyz87
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Mar 12, 2025
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Alexei reported a bpf selftest failure with recent llvm for bpf prog
file progs/arena_spin_lock.c. The failure only happens when clang is
built with cmake option LLVM_ENABLE_ASSERTIONS=ON.
The error message looks like:
```
clang: /home/yhs/work/yhs/llvm-project/llvm/lib/IR/Instructions.cpp:3460:
llvm::BitCastInst::BitCastInst(Value *, Type *, const Twine &, InsertPosition):
Assertion `castIsValid(getOpcode(), S, Ty) && "Illegal BitCast"' failed.
```
Further investigation shows that the problem is triggered in
BPF/BPFAbstractMemberAccess.cpp
for code
```
auto *BCInst =
new BitCastInst(Base, PointerType::getUnqual(BB->getContext()));
```
For the above BitCastInst, Since 'Base' has non-zero AddrSapce, the
compiler expects the type also has the same AddrSpace. But the above
PointerType::getUnqual(...) does not have AddrSpace and hence causes the
assertion failure.
Providing the proper AddrSpace for the BitCast type fixed the issue.
Co-authored-by: Yonghong Song <[email protected]>
(cherry picked from commit 5686786)
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@yonghong-song (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
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Alexei reported a bpf selftest failure with recent llvm for bpf prog
file progs/arena_spin_lock.c. The failure only happens when clang is
built with cmake option LLVM_ENABLE_ASSERTIONS=ON.
The error message looks like:
clang: /home/yhs/work/yhs/llvm-project/llvm/lib/IR/Instructions.cpp:3460: llvm::BitCastInst::BitCastInst(Value *, Type *, const Twine &, InsertPosition): Assertion `castIsValid(getOpcode(), S, Ty) && "Illegal BitCast"' failed.Further investigation shows that the problem is triggered in
BPF/BPFAbstractMemberAccess.cpp
for code
auto *BCInst = new BitCastInst(Base, PointerType::getUnqual(BB->getContext()));For the above BitCastInst, Since 'Base' has non-zero AddrSapce, the
compiler expects the type also has the same AddrSpace. But the above
PointerType::getUnqual(...) does not have AddrSpace and hence causes the
assertion failure.
Providing the proper AddrSpace for the BitCast type fixed the issue.
Backport of: #130722