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//===-- LiveStacks.cpp - Live Stack Slot Analysis -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the live stack slot analysis pass. It is analogous to
// live interval analysis except it's analyzing liveness of stack slots rather
// than registers.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LiveStacks.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "livestacks"
char LiveStacks::ID = 0;
INITIALIZE_PASS_BEGIN(LiveStacks, DEBUG_TYPE,
"Live Stack Slot Analysis", false, false)
INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
INITIALIZE_PASS_END(LiveStacks, DEBUG_TYPE,
"Live Stack Slot Analysis", false, false)
char &llvm::LiveStacksID = LiveStacks::ID;
void LiveStacks::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addPreserved<SlotIndexes>();
AU.addRequiredTransitive<SlotIndexes>();
MachineFunctionPass::getAnalysisUsage(AU);
}
void LiveStacks::releaseMemory() {
// Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
VNInfoAllocator.Reset();
S2IMap.clear();
S2RCMap.clear();
}
bool LiveStacks::runOnMachineFunction(MachineFunction &MF) {
TRI = MF.getSubtarget().getRegisterInfo();
// FIXME: No analysis is being done right now. We are relying on the
// register allocators to provide the information.
return false;
}
LiveInterval &
LiveStacks::getOrCreateInterval(int Slot, const TargetRegisterClass *RC) {
assert(Slot >= 0 && "Spill slot indice must be >= 0");
SS2IntervalMap::iterator I = S2IMap.find(Slot);
if (I == S2IMap.end()) {
I = S2IMap
.emplace(
std::piecewise_construct, std::forward_as_tuple(Slot),
std::forward_as_tuple(Register::index2StackSlot(Slot), 0.0F))
.first;
S2RCMap.insert(std::make_pair(Slot, RC));
} else {
// Use the largest common subclass register class.
const TargetRegisterClass *OldRC = S2RCMap[Slot];
S2RCMap[Slot] = TRI->getCommonSubClass(OldRC, RC);
}
return I->second;
}
/// print - Implement the dump method.
void LiveStacks::print(raw_ostream &OS, const Module*) const {
OS << "********** INTERVALS **********\n";
for (const_iterator I = begin(), E = end(); I != E; ++I) {
I->second.print(OS);
int Slot = I->first;
const TargetRegisterClass *RC = getIntervalRegClass(Slot);
if (RC)
OS << " [" << TRI->getRegClassName(RC) << "]\n";
else
OS << " [Unknown]\n";
}
}
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