/A FOSS systems blog that focus on embedded systems, Microarchitecture, hardware/software, Verilog, validations, and more. 2026-06-17T19:14:07+00:00 Daniel / Jekyll © 2026 Daniel /assets/img/favicons/favicon.ico /assets/img/favicons/favicon-96x96.png 2026-05-27T16:00:00+00:00 2026-06-17T19:13:20+00:00 /posts/chapter-9/ Daniel

Assume all your passes are wrong and have never been proven. The idea is to find failures before someone else does, pass fail at the smallest scale first, and snowball into catastrophic behaviours. Some of these include: Mis-reconstructed control flow Incorrect SSA transformations Undefined behavior misinterpretation Incorrect type recovery Silent arithmetic mismatches Standard t...

2026-05-27T16:00:00+00:00 2026-06-02T01:24:06+00:00 /posts/chapter-8/ Daniel

Optimization passes transform IR into a simpler, more canonical form without altering program semantics. The core philosophy of a pass is to reduce code and expressions to their minimal canonical form, applying transformations iteratively until a fixed point is reached (i.e., no further changes occur). Any incorrect or unsafe transformations will corrupt the output. Every pass must be determini...

2026-05-27T16:00:00+00:00 2026-06-17T19:13:20+00:00 /posts/chapter-7/ Daniel

Now that the IR is ready to go, we can begin transforming it into readable code. Pass Methodology This chapter and the preceding chapters (up to the final one) define transformation passes. Each pass operates on the IR and may modify it. Passes must be applied iteratively until a fixed point is reached i.e., until no pass produces any changes. After any modification, all passes must be r...

2026-05-27T16:00:00+00:00 2026-06-17T19:13:20+00:00 /posts/chapter-6/ Daniel

Edge-Cases Sometimes your IL will contain abstract functions that do not map 1:1 to the IR. These should be handled by flagging them while remaining as descriptive as possible. The best approach, without bloating IR nodes with extra fields, is to encode the behavior through function arguments. Ask the following questions about each function: Does it modify any registers? If yes, pass...

2026-05-27T16:00:00+00:00 2026-05-27T23:23:55+00:00 /posts/chapter-5/ Daniel

The purpose of the IL is to simplify lifting from different architectures into the IR. An added benefit is that it enables a multi-architecture decompiler: only one lifting pipeline is needed to support targets such as ARM and x86. Because lifting is the first stage in the IR pipeline, no optimizations should be used at this level. If the IL and IR are designed correctly, the IL should be abl...