1//===-- llvm/CallingConvLower.h - Calling Conventions -----------*- 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 declares the CCState and CCValAssign classes, used for lowering
11// and implementing calling conventions.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CODEGEN_CALLINGCONVLOWER_H
16#define LLVM_CODEGEN_CALLINGCONVLOWER_H
17
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/CodeGen/MachineFrameInfo.h"
20#include "llvm/CodeGen/MachineFunction.h"
21#include "llvm/CodeGen/ValueTypes.h"
22#include "llvm/IR/CallingConv.h"
23#include "llvm/Target/TargetCallingConv.h"
24
25namespace llvm {
26  class TargetRegisterInfo;
27  class TargetMachine;
28  class CCState;
29
30/// CCValAssign - Represent assignment of one arg/retval to a location.
31class CCValAssign {
32public:
33  enum LocInfo {
34    Full,   // The value fills the full location.
35    SExt,   // The value is sign extended in the location.
36    ZExt,   // The value is zero extended in the location.
37    AExt,   // The value is extended with undefined upper bits.
38    BCvt,   // The value is bit-converted in the location.
39    VExt,   // The value is vector-widened in the location.
40            // FIXME: Not implemented yet. Code that uses AExt to mean
41            // vector-widen should be fixed to use VExt instead.
42    Indirect // The location contains pointer to the value.
43    // TODO: a subset of the value is in the location.
44  };
45private:
46  /// ValNo - This is the value number begin assigned (e.g. an argument number).
47  unsigned ValNo;
48
49  /// Loc is either a stack offset or a register number.
50  unsigned Loc;
51
52  /// isMem - True if this is a memory loc, false if it is a register loc.
53  unsigned isMem : 1;
54
55  /// isCustom - True if this arg/retval requires special handling.
56  unsigned isCustom : 1;
57
58  /// Information about how the value is assigned.
59  LocInfo HTP : 6;
60
61  /// ValVT - The type of the value being assigned.
62  MVT ValVT;
63
64  /// LocVT - The type of the location being assigned to.
65  MVT LocVT;
66public:
67
68  static CCValAssign getReg(unsigned ValNo, MVT ValVT,
69                            unsigned RegNo, MVT LocVT,
70                            LocInfo HTP) {
71    CCValAssign Ret;
72    Ret.ValNo = ValNo;
73    Ret.Loc = RegNo;
74    Ret.isMem = false;
75    Ret.isCustom = false;
76    Ret.HTP = HTP;
77    Ret.ValVT = ValVT;
78    Ret.LocVT = LocVT;
79    return Ret;
80  }
81
82  static CCValAssign getCustomReg(unsigned ValNo, MVT ValVT,
83                                  unsigned RegNo, MVT LocVT,
84                                  LocInfo HTP) {
85    CCValAssign Ret;
86    Ret = getReg(ValNo, ValVT, RegNo, LocVT, HTP);
87    Ret.isCustom = true;
88    return Ret;
89  }
90
91  static CCValAssign getMem(unsigned ValNo, MVT ValVT,
92                            unsigned Offset, MVT LocVT,
93                            LocInfo HTP) {
94    CCValAssign Ret;
95    Ret.ValNo = ValNo;
96    Ret.Loc = Offset;
97    Ret.isMem = true;
98    Ret.isCustom = false;
99    Ret.HTP = HTP;
100    Ret.ValVT = ValVT;
101    Ret.LocVT = LocVT;
102    return Ret;
103  }
104
105  static CCValAssign getCustomMem(unsigned ValNo, MVT ValVT,
106                                  unsigned Offset, MVT LocVT,
107                                  LocInfo HTP) {
108    CCValAssign Ret;
109    Ret = getMem(ValNo, ValVT, Offset, LocVT, HTP);
110    Ret.isCustom = true;
111    return Ret;
112  }
113
114  unsigned getValNo() const { return ValNo; }
115  MVT getValVT() const { return ValVT; }
116
117  bool isRegLoc() const { return !isMem; }
118  bool isMemLoc() const { return isMem; }
119
120  bool needsCustom() const { return isCustom; }
121
122  unsigned getLocReg() const { assert(isRegLoc()); return Loc; }
123  unsigned getLocMemOffset() const { assert(isMemLoc()); return Loc; }
124  MVT getLocVT() const { return LocVT; }
125
126  LocInfo getLocInfo() const { return HTP; }
127  bool isExtInLoc() const {
128    return (HTP == AExt || HTP == SExt || HTP == ZExt);
129  }
130
131};
132
133/// CCAssignFn - This function assigns a location for Val, updating State to
134/// reflect the change.  It returns 'true' if it failed to handle Val.
135typedef bool CCAssignFn(unsigned ValNo, MVT ValVT,
136                        MVT LocVT, CCValAssign::LocInfo LocInfo,
137                        ISD::ArgFlagsTy ArgFlags, CCState &State);
138
139/// CCCustomFn - This function assigns a location for Val, possibly updating
140/// all args to reflect changes and indicates if it handled it. It must set
141/// isCustom if it handles the arg and returns true.
142typedef bool CCCustomFn(unsigned &ValNo, MVT &ValVT,
143                        MVT &LocVT, CCValAssign::LocInfo &LocInfo,
144                        ISD::ArgFlagsTy &ArgFlags, CCState &State);
145
146/// ParmContext - This enum tracks whether calling convention lowering is in
147/// the context of prologue or call generation. Not all backends make use of
148/// this information.
149typedef enum { Unknown, Prologue, Call } ParmContext;
150
151/// CCState - This class holds information needed while lowering arguments and
152/// return values.  It captures which registers are already assigned and which
153/// stack slots are used.  It provides accessors to allocate these values.
154class CCState {
155private:
156  CallingConv::ID CallingConv;
157  bool IsVarArg;
158  MachineFunction &MF;
159  const TargetMachine &TM;
160  const TargetRegisterInfo &TRI;
161  SmallVector<CCValAssign, 16> &Locs;
162  LLVMContext &Context;
163
164  unsigned StackOffset;
165  SmallVector<uint32_t, 16> UsedRegs;
166  unsigned FirstByValReg;
167  bool FirstByValRegValid;
168
169protected:
170  ParmContext CallOrPrologue;
171
172public:
173  CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &MF,
174          const TargetMachine &TM, SmallVector<CCValAssign, 16> &locs,
175          LLVMContext &C);
176
177  void addLoc(const CCValAssign &V) {
178    Locs.push_back(V);
179  }
180
181  LLVMContext &getContext() const { return Context; }
182  const TargetMachine &getTarget() const { return TM; }
183  MachineFunction &getMachineFunction() const { return MF; }
184  CallingConv::ID getCallingConv() const { return CallingConv; }
185  bool isVarArg() const { return IsVarArg; }
186
187  unsigned getNextStackOffset() const { return StackOffset; }
188
189  /// isAllocated - Return true if the specified register (or an alias) is
190  /// allocated.
191  bool isAllocated(unsigned Reg) const {
192    return UsedRegs[Reg/32] & (1 << (Reg&31));
193  }
194
195  /// AnalyzeFormalArguments - Analyze an array of argument values,
196  /// incorporating info about the formals into this state.
197  void AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
198                              CCAssignFn Fn);
199
200  /// AnalyzeReturn - Analyze the returned values of a return,
201  /// incorporating info about the result values into this state.
202  void AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
203                     CCAssignFn Fn);
204
205  /// CheckReturn - Analyze the return values of a function, returning
206  /// true if the return can be performed without sret-demotion, and
207  /// false otherwise.
208  bool CheckReturn(const SmallVectorImpl<ISD::OutputArg> &ArgsFlags,
209                   CCAssignFn Fn);
210
211  /// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
212  /// incorporating info about the passed values into this state.
213  void AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
214                           CCAssignFn Fn);
215
216  /// AnalyzeCallOperands - Same as above except it takes vectors of types
217  /// and argument flags.
218  void AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
219                           SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
220                           CCAssignFn Fn);
221
222  /// AnalyzeCallResult - Analyze the return values of a call,
223  /// incorporating info about the passed values into this state.
224  void AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
225                         CCAssignFn Fn);
226
227  /// AnalyzeCallResult - Same as above except it's specialized for calls which
228  /// produce a single value.
229  void AnalyzeCallResult(MVT VT, CCAssignFn Fn);
230
231  /// getFirstUnallocated - Return the first unallocated register in the set, or
232  /// NumRegs if they are all allocated.
233  unsigned getFirstUnallocated(const uint16_t *Regs, unsigned NumRegs) const {
234    for (unsigned i = 0; i != NumRegs; ++i)
235      if (!isAllocated(Regs[i]))
236        return i;
237    return NumRegs;
238  }
239
240  /// AllocateReg - Attempt to allocate one register.  If it is not available,
241  /// return zero.  Otherwise, return the register, marking it and any aliases
242  /// as allocated.
243  unsigned AllocateReg(unsigned Reg) {
244    if (isAllocated(Reg)) return 0;
245    MarkAllocated(Reg);
246    return Reg;
247  }
248
249  /// Version of AllocateReg with extra register to be shadowed.
250  unsigned AllocateReg(unsigned Reg, unsigned ShadowReg) {
251    if (isAllocated(Reg)) return 0;
252    MarkAllocated(Reg);
253    MarkAllocated(ShadowReg);
254    return Reg;
255  }
256
257  /// AllocateReg - Attempt to allocate one of the specified registers.  If none
258  /// are available, return zero.  Otherwise, return the first one available,
259  /// marking it and any aliases as allocated.
260  unsigned AllocateReg(const uint16_t *Regs, unsigned NumRegs) {
261    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
262    if (FirstUnalloc == NumRegs)
263      return 0;    // Didn't find the reg.
264
265    // Mark the register and any aliases as allocated.
266    unsigned Reg = Regs[FirstUnalloc];
267    MarkAllocated(Reg);
268    return Reg;
269  }
270
271  /// Version of AllocateReg with list of registers to be shadowed.
272  unsigned AllocateReg(const uint16_t *Regs, const uint16_t *ShadowRegs,
273                       unsigned NumRegs) {
274    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
275    if (FirstUnalloc == NumRegs)
276      return 0;    // Didn't find the reg.
277
278    // Mark the register and any aliases as allocated.
279    unsigned Reg = Regs[FirstUnalloc], ShadowReg = ShadowRegs[FirstUnalloc];
280    MarkAllocated(Reg);
281    MarkAllocated(ShadowReg);
282    return Reg;
283  }
284
285  /// AllocateStack - Allocate a chunk of stack space with the specified size
286  /// and alignment.
287  unsigned AllocateStack(unsigned Size, unsigned Align) {
288    assert(Align && ((Align-1) & Align) == 0); // Align is power of 2.
289    StackOffset = ((StackOffset + Align-1) & ~(Align-1));
290    unsigned Result = StackOffset;
291    StackOffset += Size;
292    MF.getFrameInfo()->ensureMaxAlignment(Align);
293    return Result;
294  }
295
296  /// Version of AllocateStack with extra register to be shadowed.
297  unsigned AllocateStack(unsigned Size, unsigned Align, unsigned ShadowReg) {
298    MarkAllocated(ShadowReg);
299    return AllocateStack(Size, Align);
300  }
301
302  // HandleByVal - Allocate a stack slot large enough to pass an argument by
303  // value. The size and alignment information of the argument is encoded in its
304  // parameter attribute.
305  void HandleByVal(unsigned ValNo, MVT ValVT,
306                   MVT LocVT, CCValAssign::LocInfo LocInfo,
307                   int MinSize, int MinAlign, ISD::ArgFlagsTy ArgFlags);
308
309  // First GPR that carries part of a byval aggregate that's split
310  // between registers and memory.
311  unsigned getFirstByValReg() const { return FirstByValRegValid ? FirstByValReg : 0; }
312  void setFirstByValReg(unsigned r) { FirstByValReg = r; FirstByValRegValid = true; }
313  void clearFirstByValReg() { FirstByValReg = 0; FirstByValRegValid = false; }
314  bool isFirstByValRegValid() const { return FirstByValRegValid; }
315
316  ParmContext getCallOrPrologue() const { return CallOrPrologue; }
317
318private:
319  /// MarkAllocated - Mark a register and all of its aliases as allocated.
320  void MarkAllocated(unsigned Reg);
321};
322
323
324
325} // end namespace llvm
326
327#endif
328