RFR: 8303068: Memory leak in DwarfFile::LineNumberProgram::run_line_number_program

[Johan Sjölen]

On Fri, 24 Feb 2023 04:48:53 GMT, David Holmes <dholmes at openjdk.org> wrote:

> After allocating:
> 
> _state = new (std::nothrow) LineNumberProgramState(_header);
> 
> we need to `delete _state` before returning.
> 
> Testing: tiers 1-3
> 
> Thanks.

Hi David,

`LineNumberProgram` is used in `elFile.cpp:704`, is stack allocated and has exactly one entry point: `find_filename_and_line_number`. `LineNumberProgramState` is used only internally by `LineNumberProgramState`.

`LineNumberProgram`'s current size is 120 bytes. The size of `LineNumberProgramState` is 48 bytes.

Can't we change the type of `_state` to `LineNumberProgramState`? This bloats the size up to 168 bytes, but we no longer have to care about tracking the resource or have another heap allocation call. Yes, we have to change `->` to `.`, so the change is larger, but it's conceptually simpler.

FWIW, `_state` is also always re-allocated, so I don't see why we even need the `reset()` method on it, but that's a future RFE.

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PR: https://git.openjdk.org/jdk/pull/12738