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/*
* Copyright 2016 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.
*/
//
// Optimize combinations of instructions
//
#include <algorithm>
#include <wasm.h>
#include <pass.h>
namespace wasm {
struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions>> {
void visitIf(If* curr) {
// flip branches to get rid of an i32.eqz
if (curr->ifFalse) {
auto condition = curr->condition->dynCast<Unary>();
if (condition && condition->op == EqZ && condition->value->type == i32) {
curr->condition = condition->value;
std::swap(curr->ifTrue, curr->ifFalse);
}
}
}
void visitUnary(Unary* curr) {
if (curr->op == EqZ) {
// fold comparisons that flow into an EqZ
auto* child = curr->value->dynCast<Binary>();
if (child && (child->type == i32 || child->type == i64)) {
switch (child->op) {
case Eq: child->op = Ne; break;
case Ne: child->op = Eq; break;
case LtS: child->op = GeS; break;
case LtU: child->op = GeU; break;
case LeS: child->op = GtS; break;
case LeU: child->op = GtU; break;
case GtS: child->op = LeS; break;
case GtU: child->op = LeU; break;
case GeS: child->op = LtS; break;
case GeU: child->op = LtU; break;
default: return;
}
replaceCurrent(child);
}
}
}
};
static RegisterPass<OptimizeInstructions> registerPass("optimize-instructions", "optimizes instruction combinations");
} // namespace wasm
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