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Merged
cfallin merged 3 commits into from
Mar 30, 2025
Merged

ISLE opts for x ± a == y ± b #10489

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2df12fa
ISLE opts for `x ± a == y ± b`
scottmcm Mar 30, 2025
5ad157d
Don't reassociate across `==` without a reason
scottmcm Mar 30, 2025
ec68ada
Subsume when we made it strictly better, and handle more orderings
scottmcm Mar 30, 2025
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14 changes: 14 additions & 0 deletions cranelift/codegen/src/opts/cprop.isle
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Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,20 @@
(rule (simplify (select ty (iconst_u _ 0) _ y))
(subsume y))

;; Similarly, move constants to the right side of an equality comparison.
;; `x + C == y` --> `x == y - C`
(rule (simplify (eq ty1 (iadd ty2 x k@(iconst _ _)) y))
(eq ty1 x (isub ty2 y k)))
;; `x - C == y` --> `x == y + C`
(rule (simplify (eq ty1 (isub ty2 x k@(iconst _ _)) y))
(eq ty1 x (iadd ty2 y k)))
;; `x + C != y` --> `x != y - C`
(rule (simplify (ne ty1 (iadd ty2 x k@(iconst _ _)) y))
(ne ty1 x (isub ty2 y k)))
;; `x - C != y` --> `x != y + C`
(rule (simplify (ne ty1 (isub ty2 x k@(iconst _ _)) y))
(ne ty1 x (iadd ty2 y k)))

;; Replace subtraction by a "negative" constant with addition.
;; Notably, this gives `x - (-1) == x + 1`, so other patterns don't have to
;; match the subtract-negative-one version too.
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12 changes: 12 additions & 0 deletions cranelift/codegen/src/opts/icmp.isle
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Expand Up @@ -13,6 +13,18 @@
(rule (simplify (slt (ty_int ty) x x)) (subsume (iconst_u ty 0)))
(rule (simplify (sle (ty_int ty) x x)) (subsume (iconst_u ty 1)))

;; For integers, adding or subtracting the same thing on both sides of an
;; equality check (or inequality check) doesn't change the result

(rule (simplify (eq ty (iadd _ a k) (iadd _ b k)))
(eq ty a b))
(rule (simplify (eq ty (isub _ a k) (isub _ b k)))
(eq ty a b))
(rule (simplify (ne ty (iadd _ a k) (iadd _ b k)))
(ne ty a b))
(rule (simplify (ne ty (isub _ a k) (isub _ b k)))
(ne ty a b))

;; Optimize icmp-of-icmp.
;; ne(icmp(ty, cc, x, y), 0) == icmp(ty, cc, x, y)
;; e.g. neq(ugt(x, y), 0) == ugt(x, y)
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26 changes: 26 additions & 0 deletions cranelift/filetests/filetests/egraph/cprop.clif
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Expand Up @@ -231,6 +231,32 @@ block0:
; check: v3 = iconst.i8 0
; nextln: return v3

function %icmp_sums_same_addend(i32, i32, i32) -> i8 {
block0(v0: i32, v1: i32, v2: i32):
v3 = iadd v0, v2
v4 = iadd v1, v2
v5 = icmp eq v3, v4
return v5
}

; check: v6 = icmp eq v0, v1
; nextln: return v6

function %icmp_sums_const_addends(i32, i32) -> i8 {
block0(v0: i32, v1: i32):
v3 = iconst.i32 123
v4 = iconst.i32 456
v5 = iadd v0, v3
v6 = iadd v1, v4
v7 = icmp eq v5, v6
return v7
}

; check: v11 = iconst.i32 333
; check: v12 = iadd v1, v11
; check: v15 = icmp eq v0, v12
; nextln: return v15

function %ireduce_iconst() -> i8 {
block0:
v1 = iconst.i16 -10
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47 changes: 23 additions & 24 deletions tests/disas/gc/drc/externref-globals.wat
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Expand Up @@ -108,46 +108,45 @@
;; @003b v39 = load.i64 notrap aligned readonly can_move v0+40
;; @003b v20 = iadd v39, v16
;; @003b v21 = load.i64 notrap aligned v20
;; v67 = iconst.i64 1
;; @003b v22 = iadd v21, v67 ; v67 = 1
;; v73 = iconst.i64 1
;; @003b v22 = iadd v21, v73 ; v73 = 1
;; @003b store notrap aligned v22, v20
;; @003b jump block3
;;
;; block3:
;; v72 = iadd.i64 v0, v64 ; v64 = 80
;; @003b store.i32 notrap aligned v2, v72
;; v73 = iconst.i32 1
;; v74 = band.i32 v5, v73 ; v73 = 1
;; v75 = iconst.i32 0
;; v76 = icmp.i32 eq v5, v75 ; v75 = 0
;; @003b v36 = uextend.i32 v76
;; @003b v37 = bor v74, v36
;; v85 = iadd.i64 v0, v64 ; v64 = 80
;; @003b store.i32 notrap aligned v2, v85
;; v86 = iconst.i32 1
;; v87 = band.i32 v5, v86 ; v86 = 1
;; v88 = iconst.i32 0
;; v89 = icmp.i32 eq v5, v88 ; v88 = 0
;; @003b v36 = uextend.i32 v89
;; @003b v37 = bor v87, v36
;; @003b brif v37, block7, block4
;;
;; block4:
;; @003b v42 = uextend.i64 v5
;; v77 = iconst.i64 8
;; @003b v44 = uadd_overflow_trap v42, v77, user1 ; v77 = 8
;; @003b v46 = uadd_overflow_trap v44, v77, user1 ; v77 = 8
;; v78 = load.i64 notrap aligned readonly can_move v0+48
;; @003b v47 = icmp ule v46, v78
;; v90 = iconst.i64 8
;; @003b v44 = uadd_overflow_trap v42, v90, user1 ; v90 = 8
;; @003b v46 = uadd_overflow_trap v44, v90, user1 ; v90 = 8
;; v91 = load.i64 notrap aligned readonly can_move v0+48
;; @003b v47 = icmp ule v46, v91
;; @003b trapz v47, user1
;; v79 = load.i64 notrap aligned readonly can_move v0+40
;; @003b v48 = iadd v79, v44
;; v92 = load.i64 notrap aligned readonly can_move v0+40
;; @003b v48 = iadd v92, v44
;; @003b v49 = load.i64 notrap aligned v48
;; v70 = iconst.i64 -1
;; @003b v50 = iadd v49, v70 ; v70 = -1
;; v71 = iconst.i64 0
;; @003b v51 = icmp eq v50, v71 ; v71 = 0
;; @003b brif v51, block5, block6
;; v93 = iconst.i64 1
;; v83 = icmp eq v49, v93 ; v93 = 1
;; @003b brif v83, block5, block6
Comment on lines -138 to +140
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@scottmcm scottmcm Mar 30, 2025

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A case in the wild, here: was a + -1 == 0, now a == 1.

;;
;; block5 cold:
;; @003b call fn0(v0, v5)
;; @003b jump block7
;;
;; block6:
;; v80 = iadd.i64 v49, v70 ; v70 = -1
;; @003b store notrap aligned v80, v48
;; v70 = iconst.i64 -1
;; @003b v50 = iadd.i64 v49, v70 ; v70 = -1
;; @003b store notrap aligned v50, v48
;; @003b jump block7
;;
;; block7:
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35 changes: 17 additions & 18 deletions tests/disas/gc/drc/struct-set.wat
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Expand Up @@ -110,43 +110,42 @@
;; @004a trapz v30, user1
;; @004a v31 = iadd.i64 v6, v27
;; @004a v32 = load.i64 notrap aligned v31
;; v77 = iconst.i64 1
;; @004a v33 = iadd v32, v77 ; v77 = 1
;; v84 = iconst.i64 1
;; @004a v33 = iadd v32, v84 ; v84 = 1
;; @004a store notrap aligned v33, v31
;; @004a jump block3
;;
;; block3:
;; @004a store.i32 notrap aligned little v3, v15
;; v83 = iconst.i32 1
;; v84 = band.i32 v16, v83 ; v83 = 1
;; v85 = iconst.i32 0
;; v86 = icmp.i32 eq v16, v85 ; v85 = 0
;; @004a v47 = uextend.i32 v86
;; @004a v48 = bor v84, v47
;; v96 = iconst.i32 1
;; v97 = band.i32 v16, v96 ; v96 = 1
;; v98 = iconst.i32 0
;; v99 = icmp.i32 eq v16, v98 ; v98 = 0
;; @004a v47 = uextend.i32 v99
;; @004a v48 = bor v97, v47
;; @004a brif v48, block7, block4
;;
;; block4:
;; @004a v53 = uextend.i64 v16
;; v87 = iconst.i64 8
;; @004a v55 = uadd_overflow_trap v53, v87, user1 ; v87 = 8
;; @004a v57 = uadd_overflow_trap v55, v87, user1 ; v87 = 8
;; v100 = iconst.i64 8
;; @004a v55 = uadd_overflow_trap v53, v100, user1 ; v100 = 8
;; @004a v57 = uadd_overflow_trap v55, v100, user1 ; v100 = 8
;; @004a v58 = icmp ule v57, v8
;; @004a trapz v58, user1
;; @004a v59 = iadd.i64 v6, v55
;; @004a v60 = load.i64 notrap aligned v59
;; v80 = iconst.i64 -1
;; @004a v61 = iadd v60, v80 ; v80 = -1
;; v81 = iconst.i64 0
;; @004a v62 = icmp eq v61, v81 ; v81 = 0
;; @004a brif v62, block5, block6
;; v101 = iconst.i64 1
;; v94 = icmp eq v60, v101 ; v101 = 1
;; @004a brif v94, block5, block6
;;
;; block5 cold:
;; @004a call fn0(v0, v16)
;; @004a jump block7
;;
;; block6:
;; v88 = iadd.i64 v60, v80 ; v80 = -1
;; @004a store notrap aligned v88, v59
;; v80 = iconst.i64 -1
;; @004a v61 = iadd.i64 v60, v80 ; v80 = -1
;; @004a store notrap aligned v61, v59
;; @004a jump block7
;;
;; block7:
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17 changes: 8 additions & 9 deletions tests/disas/pulley/memory-inbounds.wat
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Original file line number Diff line number Diff line change
Expand Up @@ -64,15 +64,14 @@
;;
;; wasm[0]::function[6]::offset_just_bad_v2:
;; push_frame
;; xload64le_o32 x10, x0, 88
;; xsub64_u32 x10, x10, 65536
;; xzero x11
;; xload64le_o32 x12, x0, 80
;; xadd64_u32 x12, x12, 65533
;; xzero x8
;; xeq64 x10, x10, x8
;; xselect64 x12, x10, x11, x12
;; xload32le_z x0, x12, 0
;; xload64le_o32 x9, x0, 88
;; xzero x10
;; xload64le_o32 x11, x0, 80
;; xadd64_u32 x11, x11, 65533
;; xconst32 x7, 65536
;; xeq64 x9, x9, x7
;; xselect64 x11, x9, x10, x11
;; xload32le_z x0, x11, 0
;; pop_frame
;; ret
;;
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