LLVM  3.7.0
LiveStackAnalysis.cpp
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1 //===-- LiveStackAnalysis.cpp - Live Stack Slot Analysis ------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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
12 // than registers.
13 //
14 //===----------------------------------------------------------------------===//
15 
17 #include "llvm/ADT/Statistic.h"
19 #include "llvm/CodeGen/Passes.h"
20 #include "llvm/Support/Debug.h"
24 #include <limits>
25 using namespace llvm;
26 
27 #define DEBUG_TYPE "livestacks"
28 
29 char LiveStacks::ID = 0;
30 INITIALIZE_PASS_BEGIN(LiveStacks, "livestacks",
31  "Live Stack Slot Analysis", false, false)
34  "Live Stack Slot Analysis", false, false)
35 
36 char &llvm::LiveStacksID = LiveStacks::ID;
37 
38 void LiveStacks::getAnalysisUsage(AnalysisUsage &AU) const {
39  AU.setPreservesAll();
40  AU.addPreserved<SlotIndexes>();
41  AU.addRequiredTransitive<SlotIndexes>();
43 }
44 
46  // Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
47  VNInfoAllocator.Reset();
48  S2IMap.clear();
49  S2RCMap.clear();
50 }
51 
53  TRI = MF.getSubtarget().getRegisterInfo();
54  // FIXME: No analysis is being done right now. We are relying on the
55  // register allocators to provide the information.
56  return false;
57 }
58 
61  assert(Slot >= 0 && "Spill slot indice must be >= 0");
62  SS2IntervalMap::iterator I = S2IMap.find(Slot);
63  if (I == S2IMap.end()) {
64  I = S2IMap.emplace(std::piecewise_construct, std::forward_as_tuple(Slot),
65  std::forward_as_tuple(
67  .first;
68  S2RCMap.insert(std::make_pair(Slot, RC));
69  } else {
70  // Use the largest common subclass register class.
71  const TargetRegisterClass *OldRC = S2RCMap[Slot];
72  S2RCMap[Slot] = TRI->getCommonSubClass(OldRC, RC);
73  }
74  return I->second;
75 }
76 
77 /// print - Implement the dump method.
78 void LiveStacks::print(raw_ostream &OS, const Module*) const {
79 
80  OS << "********** INTERVALS **********\n";
81  for (const_iterator I = begin(), E = end(); I != E; ++I) {
82  I->second.print(OS);
83  int Slot = I->first;
84  const TargetRegisterClass *RC = getIntervalRegClass(Slot);
85  if (RC)
86  OS << " [" << TRI->getRegClassName(RC) << "]\n";
87  else
88  OS << " [Unknown]\n";
89  }
90 }
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:114
LiveInterval - This class represents the liveness of a register, or stack slot.
Definition: LiveInterval.h:588
INITIALIZE_PASS_BEGIN(LiveStacks,"livestacks","Live Stack Slot Analysis", false, false) INITIALIZE_PASS_END(LiveStacks
const TargetRegisterClass * getCommonSubClass(const TargetRegisterClass *A, const TargetRegisterClass *B) const
getCommonSubClass - find the largest common subclass of A and B.
F(f)
const_iterator end() const
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:70
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
const TargetRegisterClass * getIntervalRegClass(int Slot) const
void Reset()
Deallocate all but the current slab and reset the current pointer to the beginning of it...
Definition: Allocator.h:189
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:75
LiveInterval & getOrCreateInterval(int Slot, const TargetRegisterClass *RC)
SlotIndexes pass.
Definition: SlotIndexes.h:334
const char * getRegClassName(const TargetRegisterClass *Class) const
getRegClassName - Returns the name of the register class.
SS2IntervalMap::const_iterator const_iterator
Live Stack Slot Analysis
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - Subclasses that override getAnalysisUsage must call this.
char & LiveStacksID
LiveStacks pass. An analysis keeping track of the liveness of stack slots.
Represent the analysis usage information of a pass.
bool runOnMachineFunction(MachineFunction &) override
runOnMachineFunction - pass entry point
Live Stack Slot false
#define I(x, y, z)
Definition: MD5.cpp:54
const_iterator begin() const
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:38
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
virtual const TargetRegisterInfo * getRegisterInfo() const
getRegisterInfo - If register information is available, return it.
void print(raw_ostream &O, const Module *=nullptr) const override
print - Implement the dump method.
static unsigned index2StackSlot(int FI)
index2StackSlot - Convert a non-negative frame index to a stack slot register value.