riscv64: Remove support for fixed offset jumps from Jump instructions #6988
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This is mostly a personal preference. It emits the exact same code.
Replaces it with `Fallthrough` which works the same way with a fixed offset of 0.
It is now only used for `CondBr`
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alexcrichton
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…#6988) * riscv64: Use `MachLabel` for Jal * riscv64: Use `Inst::gen_jump` for jumps This is mostly a personal preference. It emits the exact same code. * riscv64: Use VecMachLabel on BrTable * riscv64: Remove `BranchTarget::Offset` arm Replaces it with `Fallthrough` which works the same way with a fixed offset of 0. * riscv64: Rename `BranchTarget` It is now only used for `CondBr` * riscv64: Panic on fallthrough taken target in condbr
eduardomourar
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Sep 13, 2023
…bytecodealliance#6988) * riscv64: Use `MachLabel` for Jal * riscv64: Use `Inst::gen_jump` for jumps This is mostly a personal preference. It emits the exact same code. * riscv64: Use VecMachLabel on BrTable * riscv64: Remove `BranchTarget::Offset` arm Replaces it with `Fallthrough` which works the same way with a fixed offset of 0. * riscv64: Rename `BranchTarget` It is now only used for `CondBr` * riscv64: Panic on fallthrough taken target in condbr
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👋 Hey,
This PR removes fixed offset jumps from some instructions in the RISC-V backend. Fixed offset jumps were replaced with labels in #6955. But we still have support for them.
Currently all branch instructions use the
BranchTargetstruct, that allows a label based jump, or a fixed offset jump.This PR does the following changes:
Jalnow takes a singleMachLabelas it's targetBrTablesimilarly now takes aVec<MachLabel>CondBrstill usesBranchTarget, but it can only do a label jump, or fallthrough. It can no longer do a fixed offset jumpSince
BranchTargetis now only used inCondBr, I've renamed itCondBrTarget.