241 lines
12 KiB
C++
241 lines
12 KiB
C++
#include "Pass/Optimize/ConstPropagation.h"
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#include "IR.h"
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#include "Pass.h"
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#include <climits>
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#include <cmath>
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namespace sysy {
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char ConstPropagation::ID = 0;
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bool ConstPropagation::runOnFunction(Function *func, AnalysisManager &am) {
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bool changed = false;
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bool localChanged = true;
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while (localChanged) {
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localChanged = false;
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for (auto &bb : func->getBasicBlocks()) {
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for (auto instIter = bb->getInstructions().begin();
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instIter != bb->getInstructions().end();) {
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auto &inst = *instIter;
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bool shouldAdvanceIter = true;
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// 处理二元运算指令
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if (auto *binaryInst = dynamic_cast<BinaryInst *>(inst.get())) {
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auto *lhs = binaryInst->getLhs();
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auto *rhs = binaryInst->getRhs();
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auto *lhsConst = dynamic_cast<ConstantValue *>(lhs);
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auto *rhsConst = dynamic_cast<ConstantValue *>(rhs);
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if (lhsConst && rhsConst) {
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ConstantValue *newConst = nullptr;
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try {
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if (lhs->isInt() && rhs->isInt()) {
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int l = lhsConst->getInt();
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int r = rhsConst->getInt();
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int result;
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bool validOperation = true;
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switch (binaryInst->getKind()) {
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case Instruction::kAdd:
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// 检查加法溢出
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if ((r > 0 && l > INT_MAX - r) || (r < 0 && l < INT_MIN - r)) {
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validOperation = false;
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} else {
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result = l + r;
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}
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break;
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case Instruction::kSub:
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// 检查减法溢出
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if ((r < 0 && l > INT_MAX + r) || (r > 0 && l < INT_MIN + r)) {
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validOperation = false;
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} else {
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result = l - r;
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}
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break;
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case Instruction::kMul:
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// 检查乘法溢出
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if (l != 0 && r != 0 &&
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(std::abs(l) > INT_MAX / std::abs(r))) {
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validOperation = false;
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} else {
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result = l * r;
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}
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break;
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case Instruction::kDiv:
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if (r == 0) {
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validOperation = false;
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} else {
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result = l / r;
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}
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break;
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case Instruction::kRem:
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if (r == 0) {
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validOperation = false;
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} else {
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result = l % r;
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}
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break;
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case Instruction::kICmpEQ: result = (l == r) ? 1 : 0; break;
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case Instruction::kICmpNE: result = (l != r) ? 1 : 0; break;
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case Instruction::kICmpLT: result = (l < r) ? 1 : 0; break;
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case Instruction::kICmpGT: result = (l > r) ? 1 : 0; break;
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case Instruction::kICmpLE: result = (l <= r) ? 1 : 0; break;
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case Instruction::kICmpGE: result = (l >= r) ? 1 : 0; break;
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case Instruction::kAnd: result = (l && r) ? 1 : 0; break;
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case Instruction::kOr: result = (l || r) ? 1 : 0; break;
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default:
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validOperation = false;
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}
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if (validOperation) {
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if (binaryInst->isCmp() || binaryInst->getKind() == Instruction::kAnd ||
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binaryInst->getKind() == Instruction::kOr) {
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newConst = ConstantInteger::get(Type::getIntType(), result);
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} else {
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newConst = ConstantInteger::get(result);
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}
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}
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} else if (lhs->isFloat() && rhs->isFloat()) {
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float l = lhsConst->getFloat();
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float r = rhsConst->getFloat();
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bool validOperation = true;
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switch (binaryInst->getKind()) {
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case Instruction::kFAdd: {
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float result = l + r;
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if (std::isfinite(result)) {
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newConst = ConstantFloating::get(result);
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} else {
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validOperation = false;
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}
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break;
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}
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case Instruction::kFSub: {
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float result = l - r;
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if (std::isfinite(result)) {
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newConst = ConstantFloating::get(result);
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} else {
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validOperation = false;
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}
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break;
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}
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case Instruction::kFMul: {
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float result = l * r;
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if (std::isfinite(result)) {
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newConst = ConstantFloating::get(result);
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} else {
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validOperation = false;
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}
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break;
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}
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case Instruction::kFDiv: {
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if (std::abs(r) < std::numeric_limits<float>::epsilon()) {
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validOperation = false;
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} else {
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float result = l / r;
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if (std::isfinite(result)) {
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newConst = ConstantFloating::get(result);
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} else {
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validOperation = false;
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}
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}
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break;
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}
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case Instruction::kFCmpEQ:
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newConst = ConstantInteger::get(Type::getIntType(), (l == r) ? 1 : 0);
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break;
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case Instruction::kFCmpNE:
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newConst = ConstantInteger::get(Type::getIntType(), (l != r) ? 1 : 0);
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break;
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case Instruction::kFCmpLT:
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newConst = ConstantInteger::get(Type::getIntType(), (l < r) ? 1 : 0);
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break;
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case Instruction::kFCmpGT:
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newConst = ConstantInteger::get(Type::getIntType(), (l > r) ? 1 : 0);
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break;
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case Instruction::kFCmpLE:
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newConst = ConstantInteger::get(Type::getIntType(), (l <= r) ? 1 : 0);
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break;
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case Instruction::kFCmpGE:
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newConst = ConstantInteger::get(Type::getIntType(), (l >= r) ? 1 : 0);
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break;
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default:
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validOperation = false;
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}
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}
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} catch (...) {
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// 捕获可能的异常，跳过优化
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newConst = nullptr;
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}
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if (newConst) {
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binaryInst->replaceAllUsesWith(newConst);
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instIter = bb->getInstructions().erase(instIter);
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shouldAdvanceIter = false;
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localChanged = true;
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}
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}
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}
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// 处理一元运算指令
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else if (auto *unaryInst = dynamic_cast<UnaryInst *>(inst.get())) {
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auto *operand = unaryInst->getOperand();
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auto *operandConst = dynamic_cast<ConstantValue *>(operand);
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if (operandConst) {
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ConstantValue *newConst = nullptr;
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if (operand->isInt()) {
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int val = operandConst->getInt();
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switch (unaryInst->getKind()) {
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case Instruction::kNeg:
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if (val != INT_MIN) { // 避免溢出
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newConst = ConstantInteger::get(-val);
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}
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break;
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case Instruction::kNot:
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newConst = ConstantInteger::get(Type::getIntType(), (!val) ? 1 : 0);
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break;
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default:
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break;
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}
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} else if (operand->isFloat()) {
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float val = operandConst->getFloat();
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switch (unaryInst->getKind()) {
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case Instruction::kFNeg:
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newConst = ConstantFloating::get(-val);
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break;
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default:
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break;
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}
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}
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if (newConst) {
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unaryInst->replaceAllUsesWith(newConst);
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instIter = bb->getInstructions().erase(instIter);
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shouldAdvanceIter = false;
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localChanged = true;
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}
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}
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}
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if (shouldAdvanceIter) {
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++instIter;
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}
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}
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}
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if (localChanged) {
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changed = true;
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}
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}
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return changed;
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}
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} // namespace sysy
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