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cranelift: simplify icmp against UMAX/SMIN/SMAX (#6037)

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* cranelift: simplify `icmp` against UMAX/SMIN/SMAX

* Add tests for icmp against numeric limits
This commit is contained in:
Karl Meakin
2023-03-17 18:54:29 +00:00
committed by GitHub
parent a81c206870
commit 73cc433bdd
4 changed files with 271 additions and 43 deletions
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101
cranelift/codegen/src/opts/algebraic.isle
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@@ -377,20 +377,97 @@
(iconst _ (u64_from_imm64 1))))
extend)
;; `x < 0` is always false for unsigned integers, and `x >= 0` is always true
;; for unsigned integers, along with their reversals.
;; ult(x, 0) == false.
(rule (simplify
(icmp (fits_in_64 (ty_int ty))
(IntCC.UnsignedLessThan)
_
(iconst _ (u64_from_imm64 0))))
(iconst ty (imm64 0)))
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedLessThan) x zero @ (iconst _ (u64_from_imm64 0))))
(subsume (iconst bty (imm64 0))))
;; ule(x, 0) == eq(x, 0)
(rule (simplify
(icmp (fits_in_64 (ty_int ty))
(IntCC.UnsignedGreaterThanOrEqual)
_
(iconst _ (u64_from_imm64 0))))
(iconst ty (imm64 1)))
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedLessThanOrEqual) x zero @ (iconst _ (u64_from_imm64 0))))
(icmp bty (IntCC.Equal) x zero))
;; ugt(x, 0) == ne(x, 0).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedGreaterThan) x zero @ (iconst _ (u64_from_imm64 0))))
(icmp bty (IntCC.NotEqual) x zero))
;; uge(x, 0) == true.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedGreaterThanOrEqual) x zero @ (iconst _ (u64_from_imm64 0))))
(subsume (iconst bty (imm64 1))))
;; ult(x, UMAX) == ne(x, UMAX).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedLessThan) x umax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_umax cty)))
(icmp bty (IntCC.NotEqual) x umax))
;; ule(x, UMAX) == true.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedLessThanOrEqual) x umax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_umax cty)))
(subsume (iconst bty (imm64 1))))
;; ugt(x, UMAX) == false.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedGreaterThan) x umax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_umax cty)))
(subsume (iconst bty (imm64 0))))
;; uge(x, UMAX) == eq(x, UMAX).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.UnsignedGreaterThanOrEqual) x umax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_umax cty)))
(icmp bty (IntCC.Equal) x umax))
;; slt(x, SMIN) == false.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedLessThan) x smin @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smin cty)))
(subsume (iconst bty (imm64 0))))
;; sle(x, SMIN) == eq(x, SMIN).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedLessThanOrEqual) x smin @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smin cty)))
(icmp bty (IntCC.Equal) x smin))
;; sgt(x, SMIN) == ne(x, SMIN).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedGreaterThan) x smin @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smin cty)))
(icmp bty (IntCC.NotEqual) x smin))
;; sge(x, SMIN) == true.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedGreaterThanOrEqual) x smin @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smin cty)))
(subsume (iconst bty (imm64 1))))
;; slt(x, SMAX) == ne(x, SMAX).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedLessThan) x smax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smax cty)))
(icmp bty (IntCC.NotEqual) x smax))
;; sle(x, SMAX) == true.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedLessThanOrEqual) x smax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smax cty)))
(subsume (iconst bty (imm64 1))))
;; sgt(x, SMAX) == false.
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedGreaterThan) x smax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smax cty)))
(subsume (iconst bty (imm64 0))))
;; sge(x, SMAX) == eq(x, SMAX).
(rule (simplify
(icmp (fits_in_64 (ty_int bty)) (IntCC.SignedGreaterThanOrEqual) x smax @ (iconst cty (u64_from_imm64 y))))
(if-let $true (u64_eq y (ty_smax cty)))
(icmp bty (IntCC.Equal) x smax))
;; 32-bit integers zero-extended to 64-bit integers are never negative
(rule (simplify