42 errors in LLVM reported by PVS-Studio

[AndreyKarpov]

Hello. I've found some bugs in LLVM 15: Examples of errors that PVS-Studio found in LLVM 15.0.

[RKSimon]

Thanks @AndreyKarpov it looks like you're analyzing a lot more subprojects than in the past - a lot of flang/mlir/lldb issues!

[klausler]

Thanks @AndreyKarpov it looks like you're analyzing a lot more subprojects than in the past - a lot of flang/mlir/lldb issues!

Which "issues" pertain to flang? I read through that note and didn't recognize any code.

[RKSimon]

Thanks @AndreyKarpov it looks like you're analyzing a lot more subprojects than in the past - a lot of flang/mlir/lldb issues!

Which "issues" pertain to flang? I read through that note and didn't recognize any code.

N4 - Merger::maybeZero
N5 - FoldIntrinsicFunction

There might be others - unfortunately only the filename is in the desciption, not the full path

[klausler]

N4 is in mlir/lib/Dialect/SparseTensor/Utils/Merger.cpp, but N5 is indeed in flang.

[Dmitry314]

And what about https://github.com/llvm/llvm-project/blob/main/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp#L1222 ? Why are the expression the same?

[Dmitry314]

N2 - https://github.com/llvm/llvm-project/blob/main/mlir/include/mlir/Dialect/Tosa/Utils/ShapeUtils.h#L141

[RKSimon]

And what about https://github.com/llvm/llvm-project/blob/main/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp#L1222 ? Why are the expression the same?

I've already raised this one with @arsenm on https://reviews.llvm.org/rGfa0b93b5a0866aad3ce517daab6cd91cc67823ad

[Dmitry314]

N3 - https://github.com/llvm/llvm-project/blob/main/flang/lib/Semantics/scope.cpp#L275

[Dmitry314]

N10 - https://github.com/llvm/llvm-project/blob/main/mlir/include/mlir/ExecutionEngine/MemRefUtils.h#L194 memset

[arsenm]

I have incoming pushes for N1 and N11

[arsenm]

N1 fixed by a91c174. Test for N11 in 8acddef

[aaronpuchert]

https://github.com/llvm/llvm-project/blob/main/mlir/include/mlir/ExecutionEngine/MemRefUtils.h#L194 memset

Was wondering why we didn't catch this with -Wnonnull, but we do (after instantiation). But it's nowhere instantiated, and doesn't even instantiate without error. First

[...]/mlir/include/mlir/ExecutionEngine/MemRefUtils.h:193:20: error: no viable overloaded '='
    other.freeFunc = nullptr;
    ~~~~~~~~~~~~~~ ^ ~~~~~~~

because the argument is const OwningMemRef &&other, so we can't assign to that, and then

[...]/mlir/include/mlir/ExecutionEngine/MemRefUtils.h:194:5: error: no matching function for call to 'memset'
    memset(0, &other.descriptor, sizeof(other.descriptor));
    ^~~~~~
/usr/include/string.h:61:14: note: candidate function not viable: no known conversion from 'const mlir::OwningMemRef<T, 0>::DescriptorType *' (aka 'const StridedMemRefType<T, 0U> *') to 'int' for 2nd argument
extern void *memset (void *__s, int __c, size_t __n) __THROW __nonnull ((1));
             ^

because pointers don't implicitly convert to int. Now if we were to fix the second argument without fixing the first, we'd get

[...]/mlir/include/mlir/ExecutionEngine/MemRefUtils.h:194:42: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
    memset(0, 0, sizeof(other.descriptor));
           ~                             ^

so we finally get the warning that we want. We also get

[...]/mlir/include/mlir/ExecutionEngine/MemRefUtils.h:195:3: warning: non-void function does not return a value [-Wreturn-type]
  }
  ^

FWIW, I can't find any use of this header file except for one unit test. (That doesn't test the move constructor obviously.)