Stage2: wasm - Implement the MIR pass #10153
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This declares the initial most-used instructions for wasm as well as the data that represents them. TODO: Add binary operand opcodes. By re-using the wasm opcode values, we can emit each opcode very easily by simply using `@enumToInt()`. However, this poses a possible problem: If we use all of wasm's opcodes, it leaves us no room to use synthetic opcodes such as debugging instructions. We could use reserved opcodes, but the wasm spec may use them at some point. TODO: Check if we should perhaps use a 16bit tag where the highest bits are used for synthetic opcodes.
- This implements lowering to MIR from AIR for storing and loading of locals as well as emitting immediates. - Relocating function indexes has been simplified a lot as well as we no longer need to patch offsets and we write a relocatable value instead. - Locals are now emitted at the beginning of the function section entry meaning all offsets we generate are stable.
- 64bit immediates are now stored in 2 seperate u32's. - 64bit floats are now stored in 2 seperate u32's. - `mem_arg` is now stored as a seperate payload in extra.
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Awesome work! |
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This implements the MIR pass for the wasm backend. Right now it re-uses the values of the opcode for each MIR tag, which allows us to easily write its value to memory without having to map from MIR to a wasm opcode. We will however have to add synthetic tags such as debug lines etc. Although not all 256 values are being used, the spec does reserve them and have in the past added new opcodes to those reserved slots. However, an option could be to have synthetic tags use a
secondary_tagfield, as we will need those anyway for some of the wasm opcodes that are beyondu8. This has the added benefit that eachMIRinstruction will remain 5 bytes max, as we can keepTag1 byte, rather than 2.