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content/blog/mlir-with-rust.md
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@ -28,8 +28,11 @@ It is what LLVM works on to apply all the optimization passes, it being SSA is o
- **Strength reduction**: replacing expensive operations by less expensive but equivalent ones, e.g. replace integer multiply or divide by powers of 2 with the potentially less expensive shift left (for multiply) or shift right (for divide).
- **Register allocation**: optimize how the limited number of machine registers may be used for calculations
If you want to learn LLVM IR in detail, you should look at the [LLVM Language Reference Manual](https://llvm.org/docs/LangRef.html). If you know assembly already it shouldn't be too hard, one interesting property is that LLVM has infinite registers, a small type system, you can work with integers of any bit size (i1, i32, i1942652), although if you don't use a recent version (17+) you will find some bugs. Probably the biggest wall you will hit is learning about GEPs (Get Element Ptr), it's often misunderstood how it works, so they even have a entire documentation page for it: <https://llvm.org/docs/GetElementPtr.html>.
Another thing that may need attention are [PHI nodes](https://stackoverflow.com/questions/11485531/what-exactly-phi-instruction-does-and-how-to-use-it-in-llvm), which are how LLVM selects a value that comes from control flow branches.
If you want to learn LLVM IR in detail, you should look at the [LLVM Language Reference Manual](https://llvm.org/docs/LangRef.html). If you know assembly already it shouldn't be too hard, one interesting property is that LLVM has infinite registers, so you don't need to worry about register allocation.
It has a simple type system, you can work with integers of any bit size (i1, i32, i1942652), although if you don't use a recent version (17+) you will find some bugs using big integers.
Probably the biggest wall you will hit is learning about GEPs (Get Element Ptr), it's often misunderstood how it works, so they even have a entire documentation page for it: <https://llvm.org/docs/GetElementPtr.html>.
Another thing that may need attention are [PHI nodes](https://stackoverflow.com/questions/11485531/what-exactly-phi-instruction-does-and-how-to-use-it-in-llvm), which are how LLVM selects a value that comes from control flow branches due to the nature of SSA.
The API to build such IR have the following structures: