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riscv64: Consolidate conditional moves into one instruction #7145

Merged
merged 6 commits into from
Oct 4, 2023
Merged

riscv64: Consolidate conditional moves into one instruction #7145

merged 6 commits into from
Oct 4, 2023

Commits on Oct 4, 2023

  1. riscv64: Add codegen tests for min/max

    @alexcrichton
    alexcrichton committed Oct 4, 2023
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  2. riscv64: Remove unused Type payload from Select

    @alexcrichton
    alexcrichton committed Oct 4, 2023
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  3. riscv64: Add codegen test for brif

    @alexcrichton
    alexcrichton committed Oct 4, 2023
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  4. riscv64: Consolidate conditional moves into one instruction 

    This commit removes the `IntSelect` and `SelectReg` pseudo-instructions
from the riscv64 backend and consolidates them into the `Select`
instruction. Additionally the `Select` instruction is updated to subsume
the functionality of these two previous instructions. Namely `Select`
now operates with `ValueRegs` to handle i128 and additionally takes an
`IntegerCompare` as the condition for the conditional branch to use.

This commit touches a fair bit of the backend since conditional
selection of registers was used in quite a few places. The previous
`gen_select_*` functions are replaced with new typed equivalents of
`gen_select_{xreg,vreg,freg,regs}`. Furthermore new `cmp_*` helpers were
added to create `IntegerCompare` instructions which sort-of match
conditional branch instructions, or at least the pnemonics they use.

Finally since this affected the `select` CLIF instruction itself I went
ahead and did some refactoring there too. The `select` instruction
creates an `IntegerCompare` from its argument to use to generate the
appropriate register selection instruction. This is basically the same
thing that `brif` does and now both go through a new helper,
`lower_int_compare`, which takes a `Value` and produces an
`IntegerCompare` representing if that value is either true or false.
This enables folding an `icmp` or an `fcmp`, for example, directly into
a branching instruction.
    @alexcrichton
    alexcrichton committed Oct 4, 2023
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  5. Fix a test

    @alexcrichton
    alexcrichton committed Oct 4, 2023
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  6. Favor sign-extension in equality comparisons

    @alexcrichton
    alexcrichton committed Oct 4, 2023
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