ErlangGC.cpp revision 280031 
1//===-- ErlangGC.cpp - Erlang/OTP GC strategy -------------------*- C++ -*-===//
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 Erlang/OTP runtime-compatible garbage collector
11// (e.g. defines safe points, root initialization etc.)
12//
13// The frametable emitter is in ErlangGCPrinter.cpp.
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/CodeGen/GCs.h"
18#include "llvm/CodeGen/GCStrategy.h"
19#include "llvm/CodeGen/MachineInstrBuilder.h"
20#include "llvm/MC/MCContext.h"
21#include "llvm/MC/MCSymbol.h"
22#include "llvm/Target/TargetInstrInfo.h"
23#include "llvm/Target/TargetMachine.h"
24#include "llvm/Target/TargetSubtargetInfo.h"
25
26using namespace llvm;
27
28namespace {
29
30  class ErlangGC : public GCStrategy {
31    MCSymbol *InsertLabel(MachineBasicBlock &MBB,
32                          MachineBasicBlock::iterator MI,
33                          DebugLoc DL) const;
34  public:
35    ErlangGC();
36    bool findCustomSafePoints(GCFunctionInfo &FI, MachineFunction &MF) override;
37  };
38
39}
40
41static GCRegistry::Add<ErlangGC>
42X("erlang", "erlang-compatible garbage collector");
43
44void llvm::linkErlangGC() { }
45
46ErlangGC::ErlangGC() {
47  InitRoots = false;
48  NeededSafePoints = 1 << GC::PostCall;
49  UsesMetadata = true;
50  CustomRoots = false;
51  CustomSafePoints = true;
52}
53
54MCSymbol *ErlangGC::InsertLabel(MachineBasicBlock &MBB,
55                                MachineBasicBlock::iterator MI,
56                                DebugLoc DL) const {
57  const TargetInstrInfo *TII = MBB.getParent()->getSubtarget().getInstrInfo();
58  MCSymbol *Label = MBB.getParent()->getContext().CreateTempSymbol();
59  BuildMI(MBB, MI, DL, TII->get(TargetOpcode::GC_LABEL)).addSym(Label);
60  return Label;
61}
62
63bool ErlangGC::findCustomSafePoints(GCFunctionInfo &FI, MachineFunction &MF) {
64  for (MachineFunction::iterator BBI = MF.begin(), BBE = MF.end(); BBI != BBE;
65       ++BBI)
66    for (MachineBasicBlock::iterator MI = BBI->begin(), ME = BBI->end();
67         MI != ME; ++MI)
68
69      if (MI->getDesc().isCall()) {
70
71        // Do not treat tail call sites as safe points.
72        if (MI->getDesc().isTerminator())
73          continue;
74
75        /* Code copied from VisitCallPoint(...) */
76        MachineBasicBlock::iterator RAI = MI; ++RAI;
77        MCSymbol* Label = InsertLabel(*MI->getParent(), RAI, MI->getDebugLoc());
78        FI.addSafePoint(GC::PostCall, Label, MI->getDebugLoc());
79      }
80
81  return false;
82}
83