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Merged
tlively merged 7 commits into from
Feb 12, 2026
Merged

Add a pass to remove relaxed SIMD instructions #8300

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8e1f558
Add a pass to remove relaxed SIMD instructions
tlively Feb 11, 2026
53f34a4
Update copyright year
tlively Feb 11, 2026
c27cff1
Fix header order
tlively Feb 11, 2026
3df4f38
Merge branch 'main' into remove-relaxed-simd-pass
tlively Feb 11, 2026
8870263
address feedback
tlively Feb 11, 2026
7b16ed1
update help tests
tlively Feb 12, 2026
9081f36
Merge remote-tracking branch 'origin/remove-relaxed-simd-pass' into r…
tlively Feb 12, 2026
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1 change: 1 addition & 0 deletions src/passes/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,7 @@ set(passes_SOURCES
RemoveImports.cpp
RemoveMemoryInit.cpp
RemoveNonJSOps.cpp
RemoveRelaxedSIMD.cpp
RemoveUnusedBrs.cpp
RemoveUnusedNames.cpp
RemoveUnusedModuleElements.cpp
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102 changes: 102 additions & 0 deletions src/passes/RemoveRelaxedSIMD.cpp
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@@ -0,0 +1,102 @@
/*
* Copyright 2026 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

//
// Replaces relaxed SIMD instructions with traps.
//

#include <memory>

#include "ir/localize.h"
#include "ir/utils.h"
#include "pass.h"
#include "wasm-builder.h"
#include "wasm.h"

namespace wasm {

struct RemoveRelaxedSIMD : WalkerPass<PostWalker<RemoveRelaxedSIMD>> {
bool isFunctionParallel() override { return true; }

std::unique_ptr<Pass> create() override {
return std::make_unique<RemoveRelaxedSIMD>();
}

void replace(Expression* curr) {
auto* block =
ChildLocalizer(curr, getFunction(), *getModule(), getPassOptions())
.getChildrenReplacement();
block->list.push_back(Builder(*getModule()).makeUnreachable());
replaceCurrent(block);
}

void visitUnary(Unary* curr) {
switch (curr->op) {
case RelaxedTruncSVecF32x4ToVecI32x4:
case RelaxedTruncUVecF32x4ToVecI32x4:
case RelaxedTruncZeroSVecF64x2ToVecI32x4:
case RelaxedTruncZeroUVecF64x2ToVecI32x4:
replace(curr);
return;
default:
break;
}
}

void visitBinary(Binary* curr) {
switch (curr->op) {
case RelaxedSwizzleVecI8x16:
case RelaxedMinVecF32x4:
case RelaxedMaxVecF32x4:
case RelaxedMinVecF64x2:
case RelaxedMaxVecF64x2:
case RelaxedQ15MulrSVecI16x8:
case DotI8x16I7x16SToVecI16x8:
replace(curr);
return;
default:
break;
}
}

void visitSIMDTernary(SIMDTernary* curr) {
switch (curr->op) {
case RelaxedMaddVecF16x8:
case RelaxedNmaddVecF16x8:
case RelaxedMaddVecF32x4:
case RelaxedNmaddVecF32x4:
case RelaxedMaddVecF64x2:
case RelaxedNmaddVecF64x2:
case LaneselectI8x16:
case LaneselectI16x8:
case LaneselectI32x4:
case LaneselectI64x2:
case DotI8x16I7x16AddSToVecI32x4:
replace(curr);
return;
default:
break;
}
}

void visitFunction(Function* func) {
ReFinalize().walkFunctionInModule(func, getModule());
}
};

Pass* createRemoveRelaxedSIMDPass() { return new RemoveRelaxedSIMD(); }

} // namespace wasm
3 changes: 3 additions & 0 deletions src/passes/pass.cpp
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Expand Up @@ -408,6 +408,9 @@ void PassRegistry::registerPasses() {
registerPass("remove-non-js-ops",
"removes operations incompatible with js",
createRemoveNonJSOpsPass);
registerPass("remove-relaxed-simd",
"replaces relaxed SIMD instructions with unreachable",
createRemoveRelaxedSIMDPass);
registerPass("remove-imports",
"removes imports and replaces them with nops",
createRemoveImportsPass);
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1 change: 1 addition & 0 deletions src/passes/passes.h
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Expand Up @@ -133,6 +133,7 @@ Pass* createPrintFunctionMapPass();
Pass* createPropagateGlobalsGloballyPass();
Pass* createRandomizeBranchHintsPass();
Pass* createRemoveNonJSOpsPass();
Pass* createRemoveRelaxedSIMDPass();
Pass* createRemoveImportsPass();
Pass* createRemoveMemoryInitPass();
Pass* createRemoveUnusedBrsPass();
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3 changes: 3 additions & 0 deletions test/lit/help/wasm-metadce.test
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Expand Up @@ -391,6 +391,9 @@
;; CHECK-NEXT: --remove-non-js-ops removes operations incompatible
;; CHECK-NEXT: with js
;; CHECK-NEXT:
;; CHECK-NEXT: --remove-relaxed-simd replaces relaxed SIMD
;; CHECK-NEXT: instructions with unreachable
;; CHECK-NEXT:
;; CHECK-NEXT: --remove-unused-brs removes breaks from locations
;; CHECK-NEXT: that are not needed
;; CHECK-NEXT:
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3 changes: 3 additions & 0 deletions test/lit/help/wasm-opt.test
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Expand Up @@ -423,6 +423,9 @@
;; CHECK-NEXT: --remove-non-js-ops removes operations incompatible
;; CHECK-NEXT: with js
;; CHECK-NEXT:
;; CHECK-NEXT: --remove-relaxed-simd replaces relaxed SIMD
;; CHECK-NEXT: instructions with unreachable
;; CHECK-NEXT:
;; CHECK-NEXT: --remove-unused-brs removes breaks from locations
;; CHECK-NEXT: that are not needed
;; CHECK-NEXT:
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3 changes: 3 additions & 0 deletions test/lit/help/wasm2js.test
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Expand Up @@ -355,6 +355,9 @@
;; CHECK-NEXT: --remove-non-js-ops removes operations incompatible
;; CHECK-NEXT: with js
;; CHECK-NEXT:
;; CHECK-NEXT: --remove-relaxed-simd replaces relaxed SIMD
;; CHECK-NEXT: instructions with unreachable
;; CHECK-NEXT:
;; CHECK-NEXT: --remove-unused-brs removes breaks from locations
;; CHECK-NEXT: that are not needed
;; CHECK-NEXT:
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207 changes: 207 additions & 0 deletions test/lit/passes/remove-relaxed-simd.wast
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;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.

;; RUN: wasm-opt %s -all --remove-relaxed-simd -S -o - | filecheck %s

(module
;; CHECK: (import "" "" (func $effect (type $1) (result v128)))
(import "" "" (func $effect (result v128)))
;; CHECK: (func $unary (type $0) (param $0 v128)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (v128.not
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $unary (param v128)
(drop (i32x4.relaxed_trunc_f32x4_s (local.get 0)))
(drop (i32x4.relaxed_trunc_f32x4_u (local.get 0)))
(drop (i32x4.relaxed_trunc_f64x2_s_zero (local.get 0)))
(drop (i32x4.relaxed_trunc_f64x2_u_zero (local.get 0)))
;; Normal SIMD instruction
(drop (v128.not (local.get 0)))
)

;; CHECK: (func $binary (type $2) (param $0 v128) (param $1 v128)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (v128.xor
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: (local.get $1)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $binary (param v128 v128)
(drop (i8x16.relaxed_swizzle (local.get 0) (local.get 1)))
(drop (f32x4.relaxed_min (local.get 0) (local.get 1)))
(drop (f32x4.relaxed_max (local.get 0) (local.get 1)))
(drop (f64x2.relaxed_min (local.get 0) (local.get 1)))
(drop (f64x2.relaxed_max (local.get 0) (local.get 1)))
(drop (i16x8.relaxed_q15mulr_s (local.get 0) (local.get 1)))
(drop (i16x8.dot_i8x16_i7x16_s (local.get 0) (local.get 1)))
;; Normal SIMD instruction
(drop (v128.xor (local.get 0) (local.get 1)))
)

;; CHECK: (func $ternary (type $3) (param $0 v128) (param $1 v128) (param $2 v128)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (v128.bitselect
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: (local.get $1)
;; CHECK-NEXT: (local.get $2)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $ternary (param v128 v128 v128)
(drop (i32x4.dot_i8x16_i7x16_add_s (local.get 0) (local.get 1) (local.get 2)))
(drop (f16x8.relaxed_madd (local.get 0) (local.get 1) (local.get 2)))
(drop (f16x8.relaxed_nmadd (local.get 0) (local.get 1) (local.get 2)))
(drop (f32x4.relaxed_madd (local.get 0) (local.get 1) (local.get 2)))
(drop (f32x4.relaxed_nmadd (local.get 0) (local.get 1) (local.get 2)))
(drop (f64x2.relaxed_madd (local.get 0) (local.get 1) (local.get 2)))
(drop (f64x2.relaxed_nmadd (local.get 0) (local.get 1) (local.get 2)))
;; Normal SIMD instruction
(drop (v128.bitselect (local.get 0) (local.get 1) (local.get 2)))
)

;; CHECK: (func $refinalize (type $0) (param $0 v128)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block $l
;; CHECK-NEXT: (block
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $refinalize (param v128)
(drop
;; This block should become unreachable.
(block $l (result v128)
(i32x4.relaxed_trunc_f32x4_s (local.get 0))
)
)
)
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@kripken kripken Feb 11, 2026

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Please test a case where a child must be kept around due to effects.


;; CHECK: (func $effects (type $0) (param $0 v128)
;; CHECK-NEXT: (local $1 v128)
;; CHECK-NEXT: (local $2 v128)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block
;; CHECK-NEXT: (local.set $1
;; CHECK-NEXT: (call $effect)
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $2
;; CHECK-NEXT: (block (result v128)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (call $effect)
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $effects (param v128)
(drop
(f16x8.relaxed_madd
(call $effect)
(local.get 0)
(block (result v128)
(drop
(call $effect)
)
(local.get 0)
)
)
)
)
)
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