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ISLE rule cleanups (#5389)

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* cranelift-codegen: Use ISLE matching, not same_value

The `same_value` function just wrapped an equality test into an external
constructor, but we can do that with ISLE's equality constraints
instead.

* riscv64: Remove custom condition-code tests

The `lower_icmp` term exists solely to decide whether to sign-extend or
zero-extend the comparison operands, based on whether the condition code
requires a signed comparison. It additionally tested whether the
condition code was == or !=, but produced the same result as for other
unsigned comparisons.

We already have `signed_cond_code` in the ISLE prelude, which classifies
the total-ordering condition codes according to whether they're signed.
It also lumps == and != in the "unsigned" camp, as desired.

So this commit uses the existing method from the prelude instead of
riscv64-local definitions.

Because this version has no constraints on the left-hand side of the
rule in the unsigned case, ISLE generates Rust that always returns
`Some`. That shows that the current use of `unwrap` is justified, at the
only Rust-side call-site of `constructor_lower_icmp`, which is in
cranelift/codegen/src/isa/riscv64/lower/isle.rs.

* ISLE prelude: make offset32 infallible

This extractor always returns `Some`, so it doesn't need to be fallible.
This commit is contained in:
Jamey Sharp
2022-12-06 18:55:59 -08:00
committed by GitHub
parent 0eb22429d1
commit 29b23d41b6
7 changed files with 15 additions and 71 deletions
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20
cranelift/codegen/src/isa/aarch64/lower.isle
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@@ -189,21 +189,17 @@
;;;; Rules for `iadd_pairwise` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(rule (lower (has_type $I16X8 (iadd_pairwise (swiden_low x) (swiden_high y))))
(if-let z (same_value x y))
(saddlp8 z))
(rule (lower (has_type $I16X8 (iadd_pairwise (swiden_low x) (swiden_high x))))
(saddlp8 x))
(rule (lower (has_type $I32X4 (iadd_pairwise (swiden_low x) (swiden_high y))))
(if-let z (same_value x y))
(saddlp16 z))
(rule (lower (has_type $I32X4 (iadd_pairwise (swiden_low x) (swiden_high x))))
(saddlp16 x))
(rule (lower (has_type $I16X8 (iadd_pairwise (uwiden_low x) (uwiden_high y))))
(if-let z (same_value x y))
(uaddlp8 z))
(rule (lower (has_type $I16X8 (iadd_pairwise (uwiden_low x) (uwiden_high x))))
(uaddlp8 x))
(rule (lower (has_type $I32X4 (iadd_pairwise (uwiden_low x) (uwiden_high y))))
(if-let z (same_value x y))
(uaddlp16 z))
(rule (lower (has_type $I32X4 (iadd_pairwise (uwiden_low x) (uwiden_high x))))
(uaddlp16 x))
(rule -1 (lower (has_type ty (iadd_pairwise x y)))
(addp x y (vector_size ty)))