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tlively merged 5 commits into from
Jul 17, 2026
Merged

Remove unused results in DAE2 #8903

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1cebca9
Remove unused results in DAE2
tlively Jul 14, 2026
4d22772
remove redundant std::get
tlively Jul 17, 2026
d599b87
reduce duplication between CallRef and CallIndirect
tlively Jul 17, 2026
7594586
Remove AI test title
tlively Jul 17, 2026
0f9ce99
improve ResultLoc comments
tlively Jul 17, 2026
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625 changes: 469 additions & 156 deletions src/passes/DeadArgumentElimination2.cpp
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101 changes: 101 additions & 0 deletions test/lit/passes/dae2-results-cont.wast
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@@ -0,0 +1,101 @@
;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
;; RUN: foreach %s %t wasm-opt -all --dae2 --closed-world -S -o - | filecheck %s

(module
;; CHECK: (rec
;; CHECK-NEXT: (type $sig2 (func (result i32)))

;; CHECK: (type $cont2 (cont $sig2))

;; CHECK: (type $cont1 (cont $sig1))

;; CHECK: (type $sig1 (func (param i32) (result i32)))
(type $sig1 (func (param i32) (result i32)))
(type $sig2 (func (result i32)))
(type $cont1 (cont $sig1))
(type $cont2 (cont $sig2))

;; CHECK: (func $target (type $3)
;; CHECK-NEXT: (local $0 i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (i32.const 42)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $target (type $sig1) (param i32) (result i32)
;; Even though $sig1 is used in a continuation, $target is unreferenced,
;; so DAE2 can optimize it by giving it a new type.
(i32.const 42)
)

;; CHECK: (func $caller (type $5) (param $k (ref $cont1))
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result (ref $cont2))
;; CHECK-NEXT: (block
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: (call $target)
;; CHECK-NEXT: )
;; CHECK-NEXT: (cont.bind $cont1 $cont2
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (local.get $k)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller (param $k (ref $cont1)) (result (ref $cont2))
(drop (call $target (i32.const 0)))
(cont.bind $cont1 $cont2 (i32.const 0) (local.get $k))
)
)

(module
;; CHECK: (rec
;; CHECK-NEXT: (type $sig2 (func (result i32)))

;; CHECK: (type $cont2 (cont $sig2))

;; CHECK: (type $cont1 (cont $sig1))

;; CHECK: (type $sig1 (func (param i32) (result i32)))
(type $sig1 (func (param i32) (result i32)))
(type $sig2 (func (result i32)))
(type $cont1 (cont $sig1))
(type $cont2 (cont $sig2))

;; CHECK: (elem declare func $target)
(elem declare func $target)

;; CHECK: (func $target (type $sig1) (param $0 i32) (result i32)
;; CHECK-NEXT: (i32.const 42)
;; CHECK-NEXT: )
(func $target (type $sig1) (param i32) (result i32)
;; Same, but $target is referenced, so we cannot change its type. Because
;; $sig1 is used in a continuation, we cannot yet optimize it.
(i32.const 42)
)

;; CHECK: (func $caller (type $5) (param $k (ref $cont1))
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result (ref $cont2))
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (call $target
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (ref.func $target)
;; CHECK-NEXT: )
;; CHECK-NEXT: (cont.bind $cont1 $cont2
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (local.get $k)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller (param $k (ref $cont1)) (result (ref $cont2))
(drop (call $target (i32.const 0)))
(drop (ref.func $target))
(cont.bind $cont1 $cont2 (i32.const 0) (local.get $k))
)
)
281 changes: 281 additions & 0 deletions test/lit/passes/dae2-results-control-flow.wast
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;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
;; RUN: foreach %s %t wasm-opt -all --dae2 --closed-world -S -o - | filecheck %s

(module
;; CHECK: (func $div (type $0) (param $x i32) (param $y i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (i32.div_s
;; CHECK-NEXT: (local.get $x)
;; CHECK-NEXT: (local.get $y)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $div (param $x i32) (param $y i32) (result i32)
;; The possible trap prevents us from removing the parameters, but we can
;; still remove the result.
(i32.div_s (local.get $x) (local.get $y))
)
;; CHECK: (func $caller (type $1)
;; CHECK-NEXT: (call $div
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
(drop (call $div (i32.const 1) (i32.const 0)))
)
)

(module
;; CHECK: (global $g (mut i32) (i32.const 0))
(global $g (mut i32) (i32.const 0))
;; CHECK: (func $div (type $0) (param $x i32) (param $y i32) (result i32)
;; CHECK-NEXT: (i32.div_s
;; CHECK-NEXT: (local.get $x)
;; CHECK-NEXT: (local.get $y)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $div (param $x i32) (param $y i32) (result i32)
(i32.div_s (local.get $x) (local.get $y))
)
;; CHECK: (func $caller (type $2)
;; CHECK-NEXT: (global.set $g
;; CHECK-NEXT: (call $div
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
;; Same, but now the result is used, too.
(global.set $g (call $div (i32.const 1) (i32.const 0)))
)
)

(module
;; CHECK: (import "env" "side_effect" (func $side_effect (type $0)))
(import "env" "side_effect" (func $side_effect))
;; CHECK: (func $test (type $1) (param $cond i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (local.get $cond)
;; CHECK-NEXT: (then
;; CHECK-NEXT: (call $side_effect)
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: (else
;; CHECK-NEXT: (i32.const 2)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $test (param $cond i32) (result i32)
;; The parameter is used, but we can still remove the result.
(if (result i32)
(local.get $cond)
(then
(block (result i32)
(call $side_effect)
(i32.const 1)
)
)
(else
(i32.const 2)
)
)
)
;; CHECK: (func $caller (type $0)
;; CHECK-NEXT: (call $test
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
(drop (call $test (i32.const 1)))
)
)

(module
;; CHECK: (import "env" "side_effect" (func $side_effect (type $0)))
(import "env" "side_effect" (func $side_effect))
;; CHECK: (global $g (mut i32) (i32.const 0))
(global $g (mut i32) (i32.const 0))
;; CHECK: (func $test (type $1) (param $cond i32) (result i32)
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (local.get $cond)
;; CHECK-NEXT: (then
;; CHECK-NEXT: (call $side_effect)
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: (else
;; CHECK-NEXT: (i32.const 2)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $test (param $cond i32) (result i32)
(if (result i32) (local.get $cond)
(then
(block (result i32)
(call $side_effect)
(i32.const 1)
)
)
(else
(i32.const 2)
)
)
)
;; CHECK: (func $caller (type $0)
;; CHECK-NEXT: (global.set $g
;; CHECK-NEXT: (call $test
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
;; Same, but now the result is used.
(global.set $g (call $test (i32.const 1)))
)
)

(module
;; CHECK: (func $test (type $0) (param $cond i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block $label (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (br_if $label
;; CHECK-NEXT: (i32.const 42)
;; CHECK-NEXT: (local.get $cond)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (i32.const 100)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $test (param $cond i32) (result i32)
;; We can drop the unused result returned via a labeled block.
(block $label (result i32)
(drop
(br_if $label (i32.const 42) (local.get $cond))
)
(i32.const 100)
)
)
;; CHECK: (func $caller (type $1)
;; CHECK-NEXT: (call $test
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
(drop (call $test (i32.const 1)))
)
)

(module
;; CHECK: (global $g (mut i32) (i32.const 0))
(global $g (mut i32) (i32.const 0))
;; CHECK: (func $test (type $0) (param $cond i32) (result i32)
;; CHECK-NEXT: (block $label (result i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (br_if $label
;; CHECK-NEXT: (i32.const 42)
;; CHECK-NEXT: (local.get $cond)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (i32.const 100)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $test (param $cond i32) (result i32)
(block $label (result i32)
(drop
(br_if $label (i32.const 42) (local.get $cond))
)
(i32.const 100)
)
)
;; CHECK: (func $caller (type $2)
;; CHECK-NEXT: (global.set $g
;; CHECK-NEXT: (call $test
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
;; Same, but now the result is used.
(global.set $g (call $test (i32.const 1)))
)
)

(module
;; CHECK: (import "env" "side_effect" (func $side_effect (type $0)))
(import "env" "side_effect" (func $side_effect))
;; CHECK: (tag $tag (type $0))
(tag $tag)
;; CHECK: (func $test (type $0)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (try (result i32)
;; CHECK-NEXT: (do
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: (catch $tag
;; CHECK-NEXT: (call $side_effect)
;; CHECK-NEXT: (i32.const 2)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $test (result i32)
;; We can drop an unused result returned via a try-catch.
(try (result i32)
(do (i32.const 1))
(catch $tag
(call $side_effect)
(i32.const 2)
)
)
)
;; CHECK: (func $caller (type $0)
;; CHECK-NEXT: (call $test)
;; CHECK-NEXT: )
(func $caller
(drop (call $test))
)
)

(module
;; CHECK: (import "env" "side_effect" (func $side_effect (type $0)))
(import "env" "side_effect" (func $side_effect))
;; CHECK: (global $g (mut i32) (i32.const 0))

;; CHECK: (tag $tag (type $0))
(tag $tag)
(global $g (mut i32) (i32.const 0))
;; CHECK: (func $test (type $1) (result i32)
;; CHECK-NEXT: (try (result i32)
;; CHECK-NEXT: (do
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: (catch $tag
;; CHECK-NEXT: (call $side_effect)
;; CHECK-NEXT: (i32.const 2)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $test (result i32)
(try (result i32)
(do (i32.const 1))
(catch $tag
(call $side_effect)
(i32.const 2)
)
)
)
;; CHECK: (func $caller (type $0)
;; CHECK-NEXT: (global.set $g
;; CHECK-NEXT: (call $test)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $caller
;; Same, but now the result is used.
(global.set $g (call $test))
)
)
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