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cranelift: Optimize __multi3-style multiplications #8653

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cranelift: Optimize __multi3-style multiplications #8653

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31 changes: 31 additions & 0 deletions cranelift/codegen/src/opts/arithmetic.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -229,6 +229,37 @@
(if-let $true (u64_eq k (ty_bits_u64 half_ty)))
(uextend ty (umulhi half_ty x y)))

(rule (simplify (iadd ty (imul _ a0 b0) (ishl _ (iadd _ x y) (iconst_u _ half))))
(wide_mul ty a0 b0 x y half))
(rule (simplify (iadd ty (ishl _ (iadd _ x y) (iconst_u _ half)) (imul _ a0 b0)))
(wide_mul ty a0 b0 x y half))

(decl multi wide_mul (Type Value Value Value Value u64) Value)
(rule (wide_mul ty a0 b0 x y half)
(if-let $true (u64_eq (ty_bits ty) (u64_shl half 1)))
(if-let lo_mask (u64_sub (u64_shl 1 half) 1))
(if-let (band _ a (iconst_u _ lo_mask)) a0)
(if-let (band _ b (iconst_u _ lo_mask)) b0)
(if-let (IsCross.Result a1 b1) (is_cross a0 b0 x y))
(if-let (ushr _ a (iconst_u _ half)) a1)
(if-let (ushr _ b (iconst_u _ half)) b1)
(imul ty a b))

(type IsCross (enum (Result (a1 Value) (b1 Value))))
(decl pure multi is_cross (Value Value Value Value) IsCross)
(rule (is_cross a0 b0 x y)
(if-let a1 (is_mul_by b0 x))
(if-let b1 (is_mul_by a0 y))
(IsCross.Result a1 b1))
(rule (is_cross a0 b0 x y)
(if-let a1 (is_mul_by b0 y))
(if-let b1 (is_mul_by a0 x))
(IsCross.Result a1 b1))

(decl pure multi is_mul_by (Value Value) Value)
(rule (is_mul_by x (imul _ x y)) y)
(rule (is_mul_by x (imul _ y x)) y)

;; Cranelift's `fcvt_from_{u,s}int` instructions are polymorphic over the input
;; type so remove any unnecessary `uextend` or `sextend` to give backends
;; the chance to convert from the smallest integral type to the float. This
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103 changes: 103 additions & 0 deletions cranelift/filetests/filetests/egraph/multi3.clif
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Original file line number Diff line number Diff line change
@@ -0,0 +1,103 @@
test optimize precise-output
set opt_level=speed_and_size
target x86_64

; v3 = a_lo
; v4 = a_hi
; v5 = b_lo
; v6 = b_hi
; v11 = a0
; v14 = a1
; v9 = b0
; v17 = b1
function %multi3(i64 vmctx, i64, i32, i64, i64, i64, i64) fast {
gv0 = vmctx
gv1 = load.i64 notrap aligned readonly gv0+80

block0(v0: i64, v1: i64, v2: i32, v3: i64, v4: i64, v5: i64, v6: i64):
v7 = iconst.i64 0
v8 = iconst.i64 0xffff_ffff
v9 = band v5, v8
v10 = iconst.i64 0xffff_ffff
v11 = band v3, v10
v12 = imul v9, v11
v13 = iconst.i64 32
v14 = ushr v3, v13
v15 = imul v9, v14
v16 = iconst.i64 32
v17 = ushr v5, v16
v18 = imul v17, v11
v19 = iadd v15, v18
v20 = iconst.i64 32
v21 = ishl v19, v20
v22 = iadd v12, v21
v23 = uextend.i64 v2
v24 = global_value.i64 gv1
v25 = iadd v24, v23
store little heap v22, v25
v26 = imul v17, v14
v27 = icmp ult v19, v15
v28 = uextend.i32 v27
v29 = uextend.i64 v28
v30 = iconst.i64 32
v31 = ishl v29, v30
v32 = iconst.i64 32
v33 = ushr v19, v32
v34 = bor v31, v33
v35 = iadd v26, v34
v36 = icmp ult v22, v12
v37 = uextend.i32 v36
v38 = uextend.i64 v37
v39 = iadd v35, v38
v40 = imul v6, v3
v41 = imul v5, v4
v42 = iadd v40, v41
v43 = iadd v39, v42
v44 = uextend.i64 v2
v45 = global_value.i64 gv1
v46 = iadd v45, v44
v47 = iadd_imm v46, 8
store little heap v43, v47
return
}

; function %multi3(i64 vmctx, i64, i32, i64, i64, i64, i64) fast {
; gv0 = vmctx
; gv1 = load.i64 notrap aligned readonly gv0+80
;
; block0(v0: i64, v1: i64, v2: i32, v3: i64, v4: i64, v5: i64, v6: i64):
; v51 = imul v5, v3
; v24 = load.i64 notrap aligned readonly v0+80
; v23 = uextend.i64 v2
; v25 = iadd v24, v23
; store little heap v51, v25
; v13 = iconst.i64 32
; v17 = ushr v5, v13 ; v13 = 32
; v14 = ushr v3, v13 ; v13 = 32
; v26 = imul v17, v14
; v8 = iconst.i64 0xffff_ffff
; v9 = band v5, v8 ; v8 = 0xffff_ffff
; v15 = imul v9, v14
; v11 = band v3, v8 ; v8 = 0xffff_ffff
; v18 = imul v17, v11
; v19 = iadd v15, v18
; v27 = icmp ult v19, v15
; v53 = uextend.i64 v27
; v31 = ishl v53, v13 ; v13 = 32
; v33 = ushr v19, v13 ; v13 = 32
; v34 = bor v31, v33
; v35 = iadd v26, v34
; v12 = imul v9, v11
; v36 = icmp ult v51, v12
; v55 = uextend.i64 v36
; v39 = iadd v35, v55
; v40 = imul v6, v3
; v41 = imul v5, v4
; v42 = iadd v40, v41
; v63 = iadd v39, v42
; v50 = iconst.i64 8
; v47 = iadd v25, v50 ; v50 = 8
; store little heap v63, v47
; return
; }

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