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alexcrichton
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wasm2asm: Implement f32/f64.copysign (WebAssembly#1551)
This commit implements the `copysign` instruction for the wasm2asm binary. The implementation here is a new pass which wholesale replaces `copysign` instructions with the equivalent bit ops and reinterpretation instructions. It's intended that this matches Emscripten's implementation of lowering here.
1 parent 4615f00 commit 95990c4

10 files changed

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‎build-js.sh‎

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@@ -110,6 +110,7 @@ echo "building shared bitcode"
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$BINARYEN_SRC/passes/PrintCallGraph.cpp \
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$BINARYEN_SRC/passes/RedundantSetElimination.cpp \
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$BINARYEN_SRC/passes/RelooperJumpThreading.cpp \
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$BINARYEN_SRC/passes/RemoveCopysign.cpp \
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$BINARYEN_SRC/passes/RemoveImports.cpp \
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$BINARYEN_SRC/passes/RemoveMemory.cpp \
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$BINARYEN_SRC/passes/RemoveUnusedBrs.cpp \

‎src/passes/CMakeLists.txt‎

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@@ -30,6 +30,7 @@ SET(passes_SOURCES
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RedundantSetElimination.cpp
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RelooperJumpThreading.cpp
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ReReloop.cpp
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RemoveCopysign.cpp
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RemoveImports.cpp
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RemoveMemory.cpp
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RemoveUnusedBrs.cpp

‎src/passes/RemoveCopysign.cpp‎

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/*
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* Copyright 2018 WebAssembly Community Group participants
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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//
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// Removes the `f32.copysign` and `f64.copysign` instructions and replaces them
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// with equivalent bit operations. Primarily intended to be used with `wasm2asm`
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// where `Math.copysign` doesn't exist.
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//
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#include <wasm.h>
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#include <pass.h>
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#include "wasm-builder.h"
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namespace wasm {
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struct RemoveCopysignPass : public WalkerPass<PostWalker<RemoveCopysignPass>> {
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bool isFunctionParallel() override { return false; }
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Pass* create() override { return new RemoveCopysignPass; }
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void doWalkModule(Module* module) {
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if (!builder) builder = make_unique<Builder>(*module);
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PostWalker<RemoveCopysignPass>::doWalkModule(module);
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}
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void doWalkFunction(Function* func) {
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if (!builder) builder = make_unique<Builder>(*getModule());
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PostWalker<RemoveCopysignPass>::doWalkFunction(func);
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}
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void visitBinary(Binary *curr) {
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Literal signBit, otherBits;
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UnaryOp int2float, float2int;
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BinaryOp bitAnd, bitOr;
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switch (curr->op) {
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case CopySignFloat32:
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float2int = ReinterpretFloat32;
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int2float = ReinterpretInt32;
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bitAnd = AndInt32;
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bitOr = OrInt32;
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signBit = Literal(uint32_t(1 << 31));
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otherBits = Literal(uint32_t(1 << 31) - 1);
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break;
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case CopySignFloat64:
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float2int = ReinterpretFloat64;
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int2float = ReinterpretInt64;
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bitAnd = AndInt64;
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bitOr = OrInt64;
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signBit = Literal(uint64_t(1) << 63);
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otherBits = Literal((uint64_t(1) << 63) - 1);
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break;
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default: return;
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}
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replaceCurrent(
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builder->makeUnary(
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int2float,
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builder->makeBinary(
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bitOr,
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builder->makeBinary(
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bitAnd,
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builder->makeUnary(
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float2int,
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curr->left
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),
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builder->makeConst(otherBits)
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),
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builder->makeBinary(
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bitAnd,
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builder->makeUnary(
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float2int,
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curr->right
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),
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builder->makeConst(signBit)
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)
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)
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)
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);
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}
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private:
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std::unique_ptr<Builder> builder;
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};
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Pass *createRemoveCopysignPass() {
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return new RemoveCopysignPass();
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}
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} // namespace wasm
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‎src/passes/pass.cpp‎

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@@ -99,6 +99,7 @@ void PassRegistry::registerPasses() {
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registerPass("print-full", "print in full s-expression format", createFullPrinterPass);
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registerPass("print-call-graph", "print call graph", createPrintCallGraphPass);
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registerPass("relooper-jump-threading", "thread relooper jumps (fastcomp output only)", createRelooperJumpThreadingPass);
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registerPass("remove-copysign", "removes the copysign instruction", createRemoveCopysignPass);
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registerPass("remove-imports", "removes imports and replaces them with nops", createRemoveImportsPass);
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registerPass("remove-memory", "removes memory segments", createRemoveMemoryPass);
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registerPass("remove-unused-brs", "removes breaks from locations that are not needed", createRemoveUnusedBrsPass);

‎src/passes/passes.h‎

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@@ -56,6 +56,7 @@ Pass* createPrecomputePropagatePass();
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Pass* createPrinterPass();
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Pass* createPrintCallGraphPass();
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Pass* createRelooperJumpThreadingPass();
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Pass* createRemoveCopysignPass();
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Pass* createRemoveImportsPass();
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Pass* createRemoveMemoryPass();
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Pass* createRemoveUnusedBrsPass();

‎src/wasm2asm.h‎

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@@ -384,6 +384,7 @@ Ref Wasm2AsmBuilder::processWasm(Module* wasm) {
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addWasmCompatibilityFuncs(wasm);
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PassRunner runner(wasm);
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runner.add<AutoDrop>();
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runner.add("remove-copysign"); // must be before i64-to-i32
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runner.add("i64-to-i32-lowering");
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runner.add("flatten");
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runner.add("simplify-locals-notee-nostructure");

‎test/passes/remove-copysign.txt‎

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(module
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(type $0 (func (param f64 f64) (result f64)))
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(type $1 (func (param f32 f32) (result f32)))
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(func $copysign64 (; 0 ;) (type $0) (param $0 f64) (param $1 f64) (result f64)
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(f64.reinterpret/i64
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(i64.or
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(i64.and
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(i64.reinterpret/f64
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(get_local $0)
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)
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(i64.const 9223372036854775807)
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)
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(i64.and
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(i64.reinterpret/f64
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(get_local $1)
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)
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(i64.const -9223372036854775808)
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)
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)
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)
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)
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(func $copysign32 (; 1 ;) (type $1) (param $0 f32) (param $1 f32) (result f32)
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(f32.reinterpret/i32
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(i32.or
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(i32.and
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(i32.reinterpret/f32
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(get_local $0)
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)
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(i32.const 2147483647)
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)
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(i32.and
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(i32.reinterpret/f32
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(get_local $1)
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)
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(i32.const -2147483648)
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)
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)
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)
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)
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)

‎test/passes/remove-copysign.wast‎

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(module
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(func $copysign64 (param $0 f64) (param $1 f64) (result f64)
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(f64.copysign (get_local $0) (get_local $1)))
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(func $copysign32 (param $0 f32) (param $1 f32) (result f32)
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(f32.copysign (get_local $0) (get_local $1)))
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)
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‎test/wasm2asm/float-ops.2asm.js‎

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@@ -206,6 +206,35 @@ function asmFunc(global, env, buffer) {
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return +Math_sqrt($0);
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}
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function copysign64($0, $1) {
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$0 = +$0;
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$1 = +$1;
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var i64toi32_i32$0 = 0, i64toi32_i32$2 = 0, i64toi32_i32$3 = 0, i64toi32_i32$1 = 0;
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HEAPF64[0 >> 3] = $0;
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i64toi32_i32$0 = HEAP32[(0 + 4 | 0) >> 2] | 0;
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i64toi32_i32$2 = HEAP32[0 >> 2] | 0;
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i64toi32_i32$1 = 2147483647;
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i64toi32_i32$3 = 4294967295;
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i64toi32_i32$1 = i64toi32_i32$0 & i64toi32_i32$1 | 0;
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i64toi32_i32$3 = i64toi32_i32$2 & i64toi32_i32$3 | 0;
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HEAPF64[0 >> 3] = $1;
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i64toi32_i32$2 = HEAP32[(0 + 4 | 0) >> 2] | 0;
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i64toi32_i32$3 = HEAP32[0 >> 2] | 0;
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i64toi32_i32$0 = 2147483648;
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i64toi32_i32$0 = i64toi32_i32$2 & i64toi32_i32$0 | 0;
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i64toi32_i32$2 = i64toi32_i32$3 & 0 | 0;
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i64toi32_i32$0 = i64toi32_i32$1 | i64toi32_i32$0 | 0;
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HEAP32[0 >> 2] = i64toi32_i32$3 | i64toi32_i32$2 | 0;
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HEAP32[(0 + 4 | 0) >> 2] = i64toi32_i32$0;
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return +(+HEAPF64[0 >> 3]);
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}
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function copysign32($0, $1) {
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$0 = Math_fround($0);
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$1 = Math_fround($1);
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return Math_fround((HEAP32[0] = (HEAPF32[0] = $0, HEAP32[0]) & 2147483647 | 0 | ((HEAPF32[0] = $1, HEAP32[0]) & 2147483648 | 0) | 0, HEAPF32[0]));
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}
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function __wasm_ctz_i32(x) {
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x = x | 0;
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var $1 = 0;

‎test/wasm2asm/float-ops.wast‎

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(func (export "f64.sqrt") (param $0 f64) (result f64)
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(f64.sqrt (get_local $0)))
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;; copysign
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(func $copysign64 (param $0 f64) (param $1 f64) (result f64)
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(f64.copysign (get_local $0) (get_local $1)))
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(func $copysign32 (param $0 f32) (param $1 f32) (result f32)
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(f32.copysign (get_local $0) (get_local $1)))
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)

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