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/*
* Copyright 2015 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.
*/
//
// Misc optimizations that are useful for and/or are only valid for
// emscripten output.
//
#include <asmjs/shared-constants.h>
#include <ir/import-utils.h>
#include <ir/localize.h>
#include <ir/memory-utils.h>
#include <pass.h>
#include <shared-constants.h>
#include <wasm-builder.h>
#include <wasm.h>
namespace wasm {
namespace {
struct OptimizeCalls : public WalkerPass<PostWalker<OptimizeCalls>> {
bool isFunctionParallel() override { return true; }
Pass* create() override { return new OptimizeCalls; }
void visitCall(Call* curr) {
// special asm.js imports can be optimized
auto* func = getModule()->getFunction(curr->target);
if (!func->imported()) {
return;
}
if (func->module == GLOBAL_MATH) {
if (func->base == POW) {
if (auto* exponent = curr->operands[1]->dynCast<Const>()) {
if (exponent->value == Literal(double(2.0))) {
// This is just a square operation, do a multiply
Localizer localizer(curr->operands[0], getFunction(), getModule());
Builder builder(*getModule());
replaceCurrent(builder.makeBinary(
MulFloat64,
localizer.expr,
builder.makeLocalGet(localizer.index, localizer.expr->type)));
} else if (exponent->value == Literal(double(0.5))) {
// This is just a square root operation
replaceCurrent(
Builder(*getModule()).makeUnary(SqrtFloat64, curr->operands[0]));
}
}
}
}
}
};
} // namespace
struct PostEmscripten : public Pass {
void run(PassRunner* runner, Module* module) override {
// Apply the sbrk ptr, if it was provided.
auto sbrkPtrStr =
runner->options.getArgumentOrDefault("emscripten-sbrk-ptr", "");
if (sbrkPtrStr != "") {
auto sbrkPtr = std::stoi(sbrkPtrStr);
ImportInfo imports(*module);
auto* func = imports.getImportedFunction(ENV, "emscripten_get_sbrk_ptr");
if (func) {
Builder builder(*module);
func->body = builder.makeConst(Literal(int32_t(sbrkPtr)));
func->module = func->base = Name();
}
// Apply the sbrk ptr value, if it was provided. This lets emscripten set
// up sbrk entirely in wasm, without depending on the JS side to init
// anything; this is necessary for standalone wasm mode, in which we do
// not have any JS. Otherwise, the JS would set this value during
// startup.
auto sbrkValStr =
runner->options.getArgumentOrDefault("emscripten-sbrk-val", "");
if (sbrkValStr != "") {
uint32_t sbrkVal = std::stoi(sbrkValStr);
auto end = sbrkPtr + sizeof(sbrkVal);
// Flatten memory to make it simple to write to. Later passes can
// re-optimize it.
MemoryUtils::ensureExists(module->memory);
if (!MemoryUtils::flatten(module->memory, end, module)) {
Fatal() << "cannot apply sbrk-val since memory is not flattenable\n";
}
auto& segment = module->memory.segments[0];
assert(segment.offset->cast<Const>()->value.geti32() == 0);
assert(end <= segment.data.size());
memcpy(segment.data.data() + sbrkPtr, &sbrkVal, sizeof(sbrkVal));
}
}
// Optimize calls
OptimizeCalls().run(runner, module);
}
};
Pass* createPostEmscriptenPass() { return new PostEmscripten(); }
} // namespace wasm
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