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Merged
tlively merged 4 commits into from
May 20, 2026
Merged

Skip folding branches of unreachable If #8724

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96153b2
Skip folding branches of unreachable If
tlively May 18, 2026
53b7226
update tests
tlively May 19, 2026
66a2285
Merge branch 'main' into no-hoist-unreachable-if
tlively May 20, 2026
f678024
add test
tlively May 20, 2026
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2 changes: 1 addition & 1 deletion src/passes/OptimizeInstructions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5761,7 +5761,7 @@ struct OptimizeInstructions
}
}

if (!neverFold) {
if (!neverFold && curr->condition->type != Type::unreachable) {
// Identical code on both arms can be folded out, e.g.
//
// (select
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3 changes: 2 additions & 1 deletion src/wasm/wasm-validator.cpp
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Expand Up @@ -4340,7 +4340,8 @@ void FunctionValidator::visitContNew(ContNew* curr) {
auto cont = curr->type.getHeapType().getContinuation();
assert(cont.type.isSignature());

shouldBeTrue(HeapType::isSubType(curr->func->type.getHeapType(), cont.type),
shouldBeTrue(curr->func->type.isRef() &&
HeapType::isSubType(curr->func->type.getHeapType(), cont.type),
curr,
"cont.new function reference must be a subtype");
}
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25 changes: 25 additions & 0 deletions test/gtest/validator.cpp
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Expand Up @@ -90,3 +90,28 @@ TEST(ValidatorTest, UnreachableCastDescEq) {
WasmValidator::FlagValues::Globally | WasmValidator::FlagValues::Quiet;
EXPECT_FALSE(WasmValidator{}.validate(func.get(), module, flags));
}

TEST(ValidatorTest, ContNewUnreachable) {
Module module;
module.features = FeatureSet::All;
Builder builder(module);

auto sig = Signature(Type::none, Type::none);
module.addFunction(builder.makeFunction(
"f", {}, Signature(Type::none, Type::none), {}, builder.makeUnreachable()));

auto contType = HeapType(Continuation(sig));
auto contRefType = Type(contType, NonNullable);

// Create a cont.new with a concrete type despite an unreachable child. This
// is not valid, but we should not crash while validating it.
auto* contNew = builder.makeContNew(contType, builder.makeUnreachable());
contNew->type = contRefType;

auto testFunc = builder.makeFunction(
"test", {}, Signature(Type::none, contRefType), {}, contNew);

auto flags =
WasmValidator::FlagValues::Globally | WasmValidator::FlagValues::Quiet;
EXPECT_FALSE(WasmValidator{}.validate(testFunc.get(), module, flags));
}
6 changes: 4 additions & 2 deletions test/lit/passes/legalize-js-interface-exported-helpers.wast
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Expand Up @@ -8,8 +8,6 @@
(module
(export "get_i64" (func $get_i64))
(import "env" "imported" (func $imported (result i64)))
(export "__set_temp_ret" (func $__set_temp_ret))
(export "__get_temp_ret" (func $__get_temp_ret))
;; CHECK: (type $0 (func (result i32)))

;; CHECK: (type $1 (func (result i64)))
Expand All @@ -20,6 +18,10 @@

;; CHECK: (export "get_i64" (func $legalstub$get_i64))

;; CHECK: (export "__set_temp_ret" (func $__set_temp_ret))
(export "__set_temp_ret" (func $__set_temp_ret))
;; CHECK: (export "__get_temp_ret" (func $__get_temp_ret))
(export "__get_temp_ret" (func $__get_temp_ret))
;; CHECK: (func $get_i64 (result i64)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (call $legalfunc$imported)
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12 changes: 7 additions & 5 deletions test/lit/passes/optimize-instructions-gc.wast
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Expand Up @@ -3695,13 +3695,15 @@

;; CHECK: (func $comp-i31-struct-unreachable-if (type $4)
;; CHECK-NEXT: (ref.eq
;; CHECK-NEXT: (ref.i31
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: (then
;; CHECK-NEXT: (if (result (ref i31))
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: (then
;; CHECK-NEXT: (ref.i31
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: (else
;; CHECK-NEXT: )
;; CHECK-NEXT: (else
;; CHECK-NEXT: (ref.i31
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
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31 changes: 31 additions & 0 deletions test/lit/passes/optimize-instructions-mvp.wast
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Expand Up @@ -16046,6 +16046,37 @@
)
)
)
;; CHECK: (func $ternary-identical-arms-if-unreachable (param $x i32) (param $y i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (if (result i32)
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: (then
;; CHECK-NEXT: (i32.eqz
;; CHECK-NEXT: (local.get $x)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (else
;; CHECK-NEXT: (i32.eqz
;; CHECK-NEXT: (local.get $y)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $ternary-identical-arms-if-unreachable (param $x i32) (param $y i32)
(drop
;; Leave this to DCE instead of optimizing.
(if (result i32)
(unreachable)
(then
(i32.eqz (local.get $x))
)
(else
(i32.eqz (local.get $y))
)
)
)
)
;; CHECK: (func $ternary-identical-arms-type-change (param $x f64) (param $y f64) (param $z i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (f32.demote_f64
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