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Christian Semmler 2024-05-03 09:38:19 -04:00
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CONTRIBUTING.md
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@ -42,7 +42,7 @@ Please make yourself familiar with the [available tooling and annotations](/tool
As outlined in the [`README`](/README.md), Microsoft Visual C++ 4.20 is the compiler we use to build the game.
One important aspect to know about this compiler in the context of the decompilation project is that the assembly code generation is somewhat erratic. We call this peculiarity "compiler randomness" or entropy. In essence, what it comes down to is that changes to the code base, for instance in a header, can pseudo-randomly affect the code generation of functions in compilation units that include this header, even if the changes are completely unrelated to those functions. For example, by adding an extra (unused) inline function or an enum declaration in a header the code in some functions may wind up looking different and our main tool, [`reccmp`](/tools/README.md), will report either a (significantly) reduced or increased accuracy for those functions. This issue roughly affects around ~5% of all decompiled functions.
One important aspect to know about this compiler in the context of the decompilation project is that the assembly code generation is somewhat erratic. We call this peculiarity "compiler randomness" or entropy. In essence, what it comes down to is that changes to the code base, for instance in a header, can pseudo-randomly affect the code generation of functions in compilation units that include this header, even if the changes are completely unrelated to those functions. For example, by adding an extra (unused) inline function or an enum declaration in a header, the code in some functions may unexpectedly wind up looking different and our main tool, [`reccmp`](/tools/README.md), will report either a (significantly) reduced or increased accuracy for those functions. This issue roughly affects around ~5% of all decompiled functions.
We are currently unaware of the exact nature of this phenomenon. Unfortunately it represents a significant obstacle in our effort to achieve 100% matching binaries. If you or anyone you know has knowledge about the compiler internals that lead to the described observations, please contact us.