Stream: git-wasmtime

Topic: wasmtime / issue #9512 Class member function declarations...

Wasmtime GitHub notifications bot (Oct 24 2024 at 17:43):

SingleAccretion opened issue #9512:

Reproduction:

; main.cpp
#include "someclass.h"

int main()
{
    return SomeClass::Main();
}

; someclass.h
class SomeClass
{
public:
    int SomeMemberVariable;

    static int Main()
    {
        int x = 1;
        int y = SomeFunc(x);
        return y;
    }

    static int SomeFunc(int y)
    {
        int s = SeparateFunction();
        int z = y + 1;
        return z + s;
    }

    static int SeparateFunction();
};

; satellite.cpp
#include "someclass.h"

int SomeClass::SeparateFunction()
{
    SomeClass x = SomeClass();
    return x.SomeMemberVariable;
}

> & $env:WASI_SDK_PATH/bin/clang main.cpp satellite.cpp -o main.wasm  -g3 -target wasm32-unknown-wasip2
> lldb wasmtime -Ccache=n -Ddebug-info -Oopt-level=0 main.wasm
> (lldb) b Main
> (lldb) b SeparateFunction
> (lldb) r Main
> (lldb) p x + x ; While broken in Main
> (lldb) c
> (lldb) p x.SomeMemberVariable

Expected result: evaluation succeeds.

Actual result:

(lldb) p x.SomeMemberVariable
warning: (x86_64) JIT(0x1550de50e60)(0x000001550de50e60) 0x000002a4: DW_AT_specification(0x0000000000000291) has no decl

(lldb) error: <lldb wrapper prefix>:45:11: use of undeclared identifier '$__lldb_local_vars'
   45 |     using $__lldb_local_vars::x;
      |           ^
error: <user expression 1>:1:1: use of undeclared identifier 'x'
    1 | x.SomeMemberVariable
      | ^

The tentative root case of this is that debug info translation discards DW_AT_declaration DIEs for the member functions, leading to the two CUs (that both have SomeClass type DIEs) diverging (and LLDB ultimately ultimately caching information from the one first accessed, here main.cpp).

Wasmtime GitHub notifications bot (Oct 24 2024 at 17:43):

SingleAccretion edited issue #9512:

Reproduction:

; main.cpp
#include "someclass.h"

int main()
{
    return SomeClass::Main();
}

; someclass.h
class SomeClass
{
public:
    int SomeMemberVariable;

    static int Main()
    {
        int x = 1;
        int y = SomeFunc(x);
        return y;
    }

    static int SomeFunc(int y)
    {
        int s = SeparateFunction();
        int z = y + 1;
        return z + s;
    }

    static int SeparateFunction();
};

; satellite.cpp
#include "someclass.h"

int SomeClass::SeparateFunction()
{
    SomeClass x = SomeClass();
    return x.SomeMemberVariable;
}

> & $env:WASI_SDK_PATH/bin/clang main.cpp satellite.cpp -o main.wasm  -g3 -target wasm32-unknown-wasip2
> lldb wasmtime -Ccache=n -Ddebug-info -Oopt-level=0 main.wasm
> (lldb) b Main
> (lldb) b SeparateFunction
> (lldb) r
> (lldb) p x + x ; While broken in Main
> (lldb) c
> (lldb) p x.SomeMemberVariable

Expected result: evaluation succeeds.

Actual result:

(lldb) p x.SomeMemberVariable
warning: (x86_64) JIT(0x1550de50e60)(0x000001550de50e60) 0x000002a4: DW_AT_specification(0x0000000000000291) has no decl

(lldb) error: <lldb wrapper prefix>:45:11: use of undeclared identifier '$__lldb_local_vars'
   45 |     using $__lldb_local_vars::x;
      |           ^
error: <user expression 1>:1:1: use of undeclared identifier 'x'
    1 | x.SomeMemberVariable
      | ^

The tentative root case of this is that debug info translation discards DW_AT_declaration DIEs for the member functions, leading to the two CUs (that both have SomeClass type DIEs) diverging (and LLDB ultimately ultimately caching information from the one first accessed, here main.cpp).

Wasmtime GitHub notifications bot (Oct 24 2024 at 17:46):

SingleAccretion edited issue #9512:

Reproduction:

; main.cpp
#include "someclass.h"

int main()
{
    return SomeClass::Main();
}

; someclass.h
class SomeClass
{
public:
    int SomeMemberVariable;

    static int Main()
    {
        int x = 1;
        int y = SomeFunc(x);
        return y;
    }

    static int SomeFunc(int y)
    {
        int s = SeparateFunction();
        int z = y + 1;
        return z + s;
    }

    static int SeparateFunction();
};

; satellite.cpp
#include "someclass.h"

int SomeClass::SeparateFunction()
{
    SomeClass x = SomeClass();
    return x.SomeMemberVariable;
}

> & $env:WASI_SDK_PATH/bin/clang main.cpp satellite.cpp -o main.wasm  -g3 -target wasm32-unknown-wasip2
> lldb wasmtime -Ccache=n -Ddebug-info -Oopt-level=0 main.wasm
> (lldb) b Main
> (lldb) b SeparateFunction
> (lldb) r
> (lldb) p x + x ; While broken in Main
> (lldb) c
> (lldb) p x.SomeMemberVariable

Expected result: evaluation succeeds.

Actual result:

(lldb) p x.SomeMemberVariable
warning: (x86_64) JIT(0x1550de50e60)(0x000001550de50e60) 0x000002a4: DW_AT_specification(0x0000000000000291) has no decl

(lldb) error: <lldb wrapper prefix>:45:11: use of undeclared identifier '$__lldb_local_vars'
   45 |     using $__lldb_local_vars::x;
      |           ^
error: <user expression 1>:1:1: use of undeclared identifier 'x'
    1 | x.SomeMemberVariable
      | ^

The tentative root case of this is that debug info translation discards DW_AT_declaration DIEs for the member functions, leading to the two CUs (that both have SomeClass type DIEs) diverging (and LLDB ultimately caching information from the one first accessed, here main.cpp).

Wasmtime GitHub notifications bot (Oct 24 2024 at 18:37):

alexcrichton added the wasmtime:debugging label to Issue #9512.

Wasmtime GitHub notifications bot (Nov 06 2024 at 23:13):

alexcrichton closed issue #9512:

Reproduction:

; main.cpp
#include "someclass.h"

int main()
{
    return SomeClass::Main();
}

; someclass.h
class SomeClass
{
public:
    int SomeMemberVariable;

    static int Main()
    {
        int x = 1;
        int y = SomeFunc(x);
        return y;
    }

    static int SomeFunc(int y)
    {
        int s = SeparateFunction();
        int z = y + 1;
        return z + s;
    }

    static int SeparateFunction();
};

; satellite.cpp
#include "someclass.h"

int SomeClass::SeparateFunction()
{
    SomeClass x = SomeClass();
    return x.SomeMemberVariable;
}

> & $env:WASI_SDK_PATH/bin/clang main.cpp satellite.cpp -o main.wasm  -g3 -target wasm32-unknown-wasip2
> lldb wasmtime -Ccache=n -Ddebug-info -Oopt-level=0 main.wasm
> (lldb) b Main
> (lldb) b SeparateFunction
> (lldb) r
> (lldb) p x + x ; While broken in Main
> (lldb) c
> (lldb) p x.SomeMemberVariable

Expected result: evaluation succeeds.

Actual result:

(lldb) p x.SomeMemberVariable
warning: (x86_64) JIT(0x1550de50e60)(0x000001550de50e60) 0x000002a4: DW_AT_specification(0x0000000000000291) has no decl

(lldb) error: <lldb wrapper prefix>:45:11: use of undeclared identifier '$__lldb_local_vars'
   45 |     using $__lldb_local_vars::x;
      |           ^
error: <user expression 1>:1:1: use of undeclared identifier 'x'
    1 | x.SomeMemberVariable
      | ^

The tentative root case of this is that debug info translation discards DW_AT_declaration DIEs for the member functions, leading to the two CUs (that both have SomeClass type DIEs) diverging (and LLDB ultimately caching information from the one first accessed, here main.cpp).

Last updated: Dec 06 2025 at 06:05 UTC