mirror of
https://github.com/intel/llvm.git
synced 2026-01-21 04:14:03 +08:00
d850ca3622
Summary: Add an implementation for shrink wrapping, a frame optimization that moves callee-saved register spills from hot prologues to cold successors. (cherry picked from FBD4983706)
117 lines
3.2 KiB
C++
117 lines
3.2 KiB
C++
#include "AllocCombiner.h"
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#define DEBUG_TYPE "alloccombiner"
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using namespace llvm;
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namespace opts {
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extern bool shouldProcess(const bolt::BinaryFunction &Function);
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extern cl::opt<bolt::FrameOptimizationType> FrameOptimization;
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} // end namespace opts
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namespace llvm {
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namespace bolt {
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namespace {
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bool getStackAdjustmentSize(const BinaryContext &BC, const MCInst &Inst,
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int64_t &Adjustment) {
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return BC.MIA->evaluateSimple(Inst, Adjustment,
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std::make_pair(BC.MIA->getStackPointer(), 0LL),
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std::make_pair(0, 0LL));
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}
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bool isIndifferentToSP(const MCInst &Inst, const BinaryContext &BC) {
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if (BC.MIA->isCFI(Inst))
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return true;
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const auto II = BC.MII->get(Inst.getOpcode());
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if (BC.MIA->isTerminator(Inst) ||
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II.hasImplicitDefOfPhysReg(BC.MIA->getStackPointer(), BC.MRI.get()) ||
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II.hasImplicitUseOfPhysReg(BC.MIA->getStackPointer()))
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return false;
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for (int I = 0, E = Inst.getNumOperands(); I != E; ++I) {
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const auto &Operand = Inst.getOperand(I);
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if (Operand.isReg() && Operand.getReg() == BC.MIA->getStackPointer()) {
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return false;
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}
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}
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return true;
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}
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bool shouldProc(BinaryFunction &Function) {
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return Function.isSimple() && Function.hasCFG() &&
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opts::shouldProcess(Function) && (Function.getSize() > 0);
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}
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void runForAllWeCare(std::map<uint64_t, BinaryFunction> &BFs,
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std::function<void(BinaryFunction &)> Task) {
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for (auto &It : BFs) {
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auto &Function = It.second;
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if (shouldProc(Function))
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Task(Function);
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}
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}
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} // end anonymous namespace
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void AllocCombinerPass::combineAdjustments(BinaryContext &BC,
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BinaryFunction &BF) {
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for (auto &BB : BF) {
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MCInst *Prev = nullptr;
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for (auto I = BB.rbegin(), E = BB.rend(); I != E; ++I) {
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auto &Inst = *I;
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if (isIndifferentToSP(Inst, BC))
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continue; // Skip updating Prev
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int64_t Adjustment{0LL};
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if (!Prev || !BC.MIA->isStackAdjustment(Inst) ||
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!BC.MIA->isStackAdjustment(*Prev) ||
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!getStackAdjustmentSize(BC, *Prev, Adjustment)) {
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Prev = &Inst;
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continue;
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}
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DEBUG({
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dbgs() << "At \"" << BF.getPrintName() << "\", combining: \n";
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Inst.dump();
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Prev->dump();
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dbgs() << "Adjustment: " << Adjustment << "\n";
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});
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if (BC.MIA->isSUB(Inst))
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Adjustment = -Adjustment;
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BC.MIA->addToImm(Inst, Adjustment, BC.Ctx.get());
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DEBUG({
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dbgs() << "After adjustment:\n";
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Inst.dump();
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});
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BB.eraseInstruction(Prev);
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++NumCombined;
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Prev = &Inst;
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}
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}
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}
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void AllocCombinerPass::runOnFunctions(BinaryContext &BC,
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std::map<uint64_t, BinaryFunction> &BFs,
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std::set<uint64_t> &LargeFunctions) {
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if (opts::FrameOptimization == FOP_NONE)
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return;
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runForAllWeCare(
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BFs, [&](BinaryFunction &Function) { combineAdjustments(BC, Function); });
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outs() << "BOLT-INFO: Allocation combiner: " << NumCoalesced
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<< " empty spaces coalesced.\n";
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}
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} // end namespace bolt
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} // end namespace llvm
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