1//===-- CallingConvLower.cpp - Calling Conventions ------------------------===//
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 CCState class, used for lowering and implementing
11// calling conventions.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/CodeGen/CallingConvLower.h"
16#include "llvm/CodeGen/MachineFrameInfo.h"
17#include "llvm/CodeGen/MachineRegisterInfo.h"
18#include "llvm/IR/DataLayout.h"
19#include "llvm/Support/Debug.h"
20#include "llvm/Support/ErrorHandling.h"
21#include "llvm/Support/SaveAndRestore.h"
22#include "llvm/Support/raw_ostream.h"
23#include "llvm/Target/TargetLowering.h"
24#include "llvm/Target/TargetRegisterInfo.h"
25#include "llvm/Target/TargetSubtargetInfo.h"
26using namespace llvm;
27
28CCState::CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &mf,
29                 SmallVectorImpl<CCValAssign> &locs, LLVMContext &C)
30    : CallingConv(CC), IsVarArg(isVarArg), MF(mf),
31      TRI(*MF.getSubtarget().getRegisterInfo()), Locs(locs), Context(C),
32      CallOrPrologue(Unknown) {
33  // No stack is used.
34  StackOffset = 0;
35
36  clearByValRegsInfo();
37  UsedRegs.resize((TRI.getNumRegs()+31)/32);
38}
39
40// HandleByVal - Allocate space on the stack large enough to pass an argument
41// by value. The size and alignment information of the argument is encoded in
42// its parameter attribute.
43void CCState::HandleByVal(unsigned ValNo, MVT ValVT,
44                          MVT LocVT, CCValAssign::LocInfo LocInfo,
45                          int MinSize, int MinAlign,
46                          ISD::ArgFlagsTy ArgFlags) {
47  unsigned Align = ArgFlags.getByValAlign();
48  unsigned Size  = ArgFlags.getByValSize();
49  if (MinSize > (int)Size)
50    Size = MinSize;
51  if (MinAlign > (int)Align)
52    Align = MinAlign;
53  MF.getFrameInfo()->ensureMaxAlignment(Align);
54  MF.getSubtarget().getTargetLowering()->HandleByVal(this, Size, Align);
55  Size = unsigned(RoundUpToAlignment(Size, MinAlign));
56  unsigned Offset = AllocateStack(Size, Align);
57  addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
58}
59
60/// MarkAllocated - Mark a register and all of its aliases as allocated.
61void CCState::MarkAllocated(unsigned Reg) {
62  for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
63    UsedRegs[*AI/32] |= 1 << (*AI&31);
64}
65
66/// AnalyzeFormalArguments - Analyze an array of argument values,
67/// incorporating info about the formals into this state.
68void
69CCState::AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
70                                CCAssignFn Fn) {
71  unsigned NumArgs = Ins.size();
72
73  for (unsigned i = 0; i != NumArgs; ++i) {
74    MVT ArgVT = Ins[i].VT;
75    ISD::ArgFlagsTy ArgFlags = Ins[i].Flags;
76    if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
77#ifndef NDEBUG
78      dbgs() << "Formal argument #" << i << " has unhandled type "
79             << EVT(ArgVT).getEVTString() << '\n';
80#endif
81      llvm_unreachable(nullptr);
82    }
83  }
84}
85
86/// CheckReturn - Analyze the return values of a function, returning true if
87/// the return can be performed without sret-demotion, and false otherwise.
88bool CCState::CheckReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
89                          CCAssignFn Fn) {
90  // Determine which register each value should be copied into.
91  for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
92    MVT VT = Outs[i].VT;
93    ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
94    if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
95      return false;
96  }
97  return true;
98}
99
100/// AnalyzeReturn - Analyze the returned values of a return,
101/// incorporating info about the result values into this state.
102void CCState::AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
103                            CCAssignFn Fn) {
104  // Determine which register each value should be copied into.
105  for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
106    MVT VT = Outs[i].VT;
107    ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
108    if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this)) {
109#ifndef NDEBUG
110      dbgs() << "Return operand #" << i << " has unhandled type "
111             << EVT(VT).getEVTString() << '\n';
112#endif
113      llvm_unreachable(nullptr);
114    }
115  }
116}
117
118/// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
119/// incorporating info about the passed values into this state.
120void CCState::AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
121                                  CCAssignFn Fn) {
122  unsigned NumOps = Outs.size();
123  for (unsigned i = 0; i != NumOps; ++i) {
124    MVT ArgVT = Outs[i].VT;
125    ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
126    if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
127#ifndef NDEBUG
128      dbgs() << "Call operand #" << i << " has unhandled type "
129             << EVT(ArgVT).getEVTString() << '\n';
130#endif
131      llvm_unreachable(nullptr);
132    }
133  }
134}
135
136/// AnalyzeCallOperands - Same as above except it takes vectors of types
137/// and argument flags.
138void CCState::AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
139                                  SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
140                                  CCAssignFn Fn) {
141  unsigned NumOps = ArgVTs.size();
142  for (unsigned i = 0; i != NumOps; ++i) {
143    MVT ArgVT = ArgVTs[i];
144    ISD::ArgFlagsTy ArgFlags = Flags[i];
145    if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
146#ifndef NDEBUG
147      dbgs() << "Call operand #" << i << " has unhandled type "
148             << EVT(ArgVT).getEVTString() << '\n';
149#endif
150      llvm_unreachable(nullptr);
151    }
152  }
153}
154
155/// AnalyzeCallResult - Analyze the return values of a call,
156/// incorporating info about the passed values into this state.
157void CCState::AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
158                                CCAssignFn Fn) {
159  for (unsigned i = 0, e = Ins.size(); i != e; ++i) {
160    MVT VT = Ins[i].VT;
161    ISD::ArgFlagsTy Flags = Ins[i].Flags;
162    if (Fn(i, VT, VT, CCValAssign::Full, Flags, *this)) {
163#ifndef NDEBUG
164      dbgs() << "Call result #" << i << " has unhandled type "
165             << EVT(VT).getEVTString() << '\n';
166#endif
167      llvm_unreachable(nullptr);
168    }
169  }
170}
171
172/// AnalyzeCallResult - Same as above except it's specialized for calls which
173/// produce a single value.
174void CCState::AnalyzeCallResult(MVT VT, CCAssignFn Fn) {
175  if (Fn(0, VT, VT, CCValAssign::Full, ISD::ArgFlagsTy(), *this)) {
176#ifndef NDEBUG
177    dbgs() << "Call result has unhandled type "
178           << EVT(VT).getEVTString() << '\n';
179#endif
180    llvm_unreachable(nullptr);
181  }
182}
183
184static bool isValueTypeInRegForCC(CallingConv::ID CC, MVT VT) {
185  if (VT.isVector())
186    return true; // Assume -msse-regparm might be in effect.
187  if (!VT.isInteger())
188    return false;
189  if (CC == CallingConv::X86_VectorCall || CC == CallingConv::X86_FastCall)
190    return true;
191  return false;
192}
193
194void CCState::getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> &Regs,
195                                          MVT VT, CCAssignFn Fn) {
196  unsigned SavedStackOffset = StackOffset;
197  unsigned NumLocs = Locs.size();
198
199  // Set the 'inreg' flag if it is used for this calling convention.
200  ISD::ArgFlagsTy Flags;
201  if (isValueTypeInRegForCC(CallingConv, VT))
202    Flags.setInReg();
203
204  // Allocate something of this value type repeatedly until we get assigned a
205  // location in memory.
206  bool HaveRegParm = true;
207  while (HaveRegParm) {
208    if (Fn(0, VT, VT, CCValAssign::Full, Flags, *this)) {
209#ifndef NDEBUG
210      dbgs() << "Call has unhandled type " << EVT(VT).getEVTString()
211             << " while computing remaining regparms\n";
212#endif
213      llvm_unreachable(nullptr);
214    }
215    HaveRegParm = Locs.back().isRegLoc();
216  }
217
218  // Copy all the registers from the value locations we added.
219  assert(NumLocs < Locs.size() && "CC assignment failed to add location");
220  for (unsigned I = NumLocs, E = Locs.size(); I != E; ++I)
221    if (Locs[I].isRegLoc())
222      Regs.push_back(MCPhysReg(Locs[I].getLocReg()));
223
224  // Clear the assigned values and stack memory. We leave the registers marked
225  // as allocated so that future queries don't return the same registers, i.e.
226  // when i64 and f64 are both passed in GPRs.
227  StackOffset = SavedStackOffset;
228  Locs.resize(NumLocs);
229}
230
231void CCState::analyzeMustTailForwardedRegisters(
232    SmallVectorImpl<ForwardedRegister> &Forwards, ArrayRef<MVT> RegParmTypes,
233    CCAssignFn Fn) {
234  // Oftentimes calling conventions will not user register parameters for
235  // variadic functions, so we need to assume we're not variadic so that we get
236  // all the registers that might be used in a non-variadic call.
237  SaveAndRestore<bool> SavedVarArg(IsVarArg, false);
238
239  for (MVT RegVT : RegParmTypes) {
240    SmallVector<MCPhysReg, 8> RemainingRegs;
241    getRemainingRegParmsForType(RemainingRegs, RegVT, Fn);
242    const TargetLowering *TL = MF.getSubtarget().getTargetLowering();
243    const TargetRegisterClass *RC = TL->getRegClassFor(RegVT);
244    for (MCPhysReg PReg : RemainingRegs) {
245      unsigned VReg = MF.addLiveIn(PReg, RC);
246      Forwards.push_back(ForwardedRegister(VReg, PReg, RegVT));
247    }
248  }
249}
250