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Generalize u/sextend constant folding to all types (#5706)

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Also move these optimization rules to cprop.isle; it's where all the
other similar rules are.

Like the other cprop rules, these can subsume any other rules. We can't
do better than reducing an expression to a constant.

The new i64_sextend_imm64 and u64_uextend_imm64 constructors are useful
helpers to clean up other code. I applied them to `imm64_icmp` while I
was here, as well as using the existing `ty_mask` helper to clean up
`imm64_masked`.
This commit is contained in:
Jamey Sharp
2023-02-03 17:29:21 -08:00
committed by GitHub
parent 331bc281a1
commit 97381792ac
4 changed files with 30 additions and 35 deletions
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6
cranelift/codegen/src/opts/algebraic.isle
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@@ -6,12 +6,6 @@
;; than a piece of the input or a new node that we construct; but we
;; can freely rewrite e.g. `x+y-y` to `x`.
;; uextend/sextend of a constant.
(rule (simplify (uextend $I64 (iconst $I32 (u64_from_imm64 imm))))
(iconst $I64 (imm64 (u64_uextend_u32 imm))))
(rule (simplify (sextend $I64 (iconst $I32 (u64_from_imm64 imm))))
(iconst $I64 (imm64 (u64_sextend_u32 imm))))
;; x+0 == 0+x == x.
(rule (simplify (iadd ty
x

6
cranelift/codegen/src/opts/cprop.isle
View File

@@ -70,6 +70,12 @@
(iconst _ k2)))
(subsume (iconst ty (imm64_sshr ty k1 k2))))
(rule (simplify (uextend wide (iconst narrow imm)))
(subsume (iconst wide (imm64 (u64_uextend_imm64 narrow imm)))))
(rule (simplify (sextend wide (iconst narrow imm)))
(subsume (iconst wide (imm64_masked wide (i64_as_u64 (i64_sextend_imm64 narrow imm))))))
(rule (simplify
(icmp result_ty
cc