[Lldb-commits] [lldb] [LLDB][NativePDB] Check function type before casting (PR #166090)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: nerix (Nerixyz)

<details>
<summary>Changes</summary>

When I ran the shell tests on Windows locally, LLDB crashed on [`TestIRMemoryMapWindows.test`](https://github.com/llvm/llvm-project/blob/9cf51a7a3bacd67a71d010726eaf6ee3ee7ad85e/lldb/test/Shell/Expr/TestIRMemoryMapWindows.test). It crashed, because it tried to create a function type for a type index that wasn't a function type. `CreateFunctionDeclFromId` (the function changed in this PR) creates a function decl for `LF_FUNC_ID` and `LF_MFUNC_ID` records. These records are in the IPI stream, which only contains IDs and references to the main type stream, TPI. Specifically, it crashed when handling the `0x32BB` IPI record:
```
IPI:                   
   0x32BB | LF_FUNC_ID [size = 32, hash = 0x221F8]
            name = invoke_main, type = 0x141E, parent scope = <no type>
TPI:
   0x141E | LF_MODIFIER [size = 12, hash = 0x272]
            referent = 0x0012 (long), modifiers = const
```

The type of `0x32BB` here is obviously wrong, as it's not a function type.
The confusing part is that `invoke_main` has two `LF_FUNC_ID` records. The other one is a bit earlier in the stream and has a correct TPI record:

```
IPI:
   0x10FD | LF_FUNC_ID [size = 32, hash = 0x3D559]
            name = invoke_main, type = 0x1141, parent scope = <no type>
TPI:
   0x1141 | LF_PROCEDURE [size = 16, hash = 0x239DB]
            return type = 0x0074 (int), # args = 0, param list = 0x1001
            calling conv = cdecl, options = None
```

Unfortunately, I can't reproduce this anymore. I experimented with using lld-link instead of MS' link. There, I couldn't reproduce it. Switching back to MS' link resulted in the correct PDB again.

I suspect the issue is related to incremental linking.

---
Full diff: https://github.com/llvm/llvm-project/pull/166090.diff


1 Files Affected:

- (modified) lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp (+2-1) 


``````````diff
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
index e7fddf08967fb..85f0c3873447b 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
@@ -1010,7 +1010,8 @@ PdbAstBuilder::CreateFunctionDeclFromId(PdbTypeSymId func_tid,
     lldbassert(false && "Invalid function id type!");
   }
   clang::QualType func_qt = GetOrCreateType(func_ti);
-  if (func_qt.isNull() || !parent)
+  if (func_qt.isNull() || !parent ||
+      !llvm::isa<clang::FunctionProtoType>(func_qt))
     return nullptr;
   CompilerType func_ct = ToCompilerType(func_qt);
   uint32_t param_count =

``````````

</details>


https://github.com/llvm/llvm-project/pull/166090