1 //===-- LiveStackAnalysis.cpp - Live Stack Slot Analysis ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the live stack slot analysis pass. It is analogous to
11 // live interval analysis except it's analyzing liveness of stack slots rather
14 //===----------------------------------------------------------------------===//
16 #include "llvm/CodeGen/LiveStackAnalysis.h"
17 #include "llvm/ADT/Statistic.h"
18 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
19 #include "llvm/CodeGen/Passes.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include "llvm/Target/TargetRegisterInfo.h"
26 #define DEBUG_TYPE "livestacks"
28 char LiveStacks::ID = 0;
29 INITIALIZE_PASS_BEGIN(LiveStacks, "livestacks",
30 "Live Stack Slot Analysis", false, false)
31 INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
32 INITIALIZE_PASS_END(LiveStacks, "livestacks",
33 "Live Stack Slot Analysis", false, false)
35 char &llvm::LiveStacksID = LiveStacks::ID;
37 void LiveStacks::getAnalysisUsage(AnalysisUsage &AU) const {
39 AU.addPreserved<SlotIndexes>();
40 AU.addRequiredTransitive<SlotIndexes>();
41 MachineFunctionPass::getAnalysisUsage(AU);
44 void LiveStacks::releaseMemory() {
45 // Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
46 VNInfoAllocator.Reset();
51 bool LiveStacks::runOnMachineFunction(MachineFunction &MF) {
52 TRI = MF.getTarget().getRegisterInfo();
53 // FIXME: No analysis is being done right now. We are relying on the
54 // register allocators to provide the information.
59 LiveStacks::getOrCreateInterval(int Slot, const TargetRegisterClass *RC) {
60 assert(Slot >= 0 && "Spill slot indice must be >= 0");
61 SS2IntervalMap::iterator I = S2IMap.find(Slot);
62 if (I == S2IMap.end()) {
63 I = S2IMap.insert(I, std::make_pair(Slot,
64 LiveInterval(TargetRegisterInfo::index2StackSlot(Slot), 0.0F)));
65 S2RCMap.insert(std::make_pair(Slot, RC));
67 // Use the largest common subclass register class.
68 const TargetRegisterClass *OldRC = S2RCMap[Slot];
69 S2RCMap[Slot] = TRI->getCommonSubClass(OldRC, RC);
74 /// print - Implement the dump method.
75 void LiveStacks::print(raw_ostream &OS, const Module*) const {
77 OS << "********** INTERVALS **********\n";
78 for (const_iterator I = begin(), E = end(); I != E; ++I) {
81 const TargetRegisterClass *RC = getIntervalRegClass(Slot);
83 OS << " [" << RC->getName() << "]\n";