CallingConvLower.h revision 234353 
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/MachineFunction.h"
20#include "llvm/CodeGen/ValueTypes.h"
21#include "llvm/Target/TargetCallingConv.h"
22#include "llvm/CallingConv.h"
23
24namespace llvm {
25  class TargetRegisterInfo;
26  class TargetMachine;
27  class CCState;
28
29/// CCValAssign - Represent assignment of one arg/retval to a location.
30class CCValAssign {
31public:
32  enum LocInfo {
33    Full,   // The value fills the full location.
34    SExt,   // The value is sign extended in the location.
35    ZExt,   // The value is zero extended in the location.
36    AExt,   // The value is extended with undefined upper bits.
37    BCvt,   // The value is bit-converted in the location.
38    VExt,   // The value is vector-widened in the location.
39            // FIXME: Not implemented yet. Code that uses AExt to mean
40            // vector-widen should be fixed to use VExt instead.
41    Indirect // The location contains pointer to the value.
42    // TODO: a subset of the value is in the location.
43  };
44private:
45  /// ValNo - This is the value number begin assigned (e.g. an argument number).
46  unsigned ValNo;
47
48  /// Loc is either a stack offset or a register number.
49  unsigned Loc;
50
51  /// isMem - True if this is a memory loc, false if it is a register loc.
52  bool isMem : 1;
53
54  /// isCustom - True if this arg/retval requires special handling.
55  bool isCustom : 1;
56
57  /// Information about how the value is assigned.
58  LocInfo HTP : 6;
59
60  /// ValVT - The type of the value being assigned.
61  MVT ValVT;
62
63  /// LocVT - The type of the location being assigned to.
64  MVT LocVT;
65public:
66
67  static CCValAssign getReg(unsigned ValNo, MVT ValVT,
68                            unsigned RegNo, MVT LocVT,
69                            LocInfo HTP) {
70    CCValAssign Ret;
71    Ret.ValNo = ValNo;
72    Ret.Loc = RegNo;
73    Ret.isMem = false;
74    Ret.isCustom = false;
75    Ret.HTP = HTP;
76    Ret.ValVT = ValVT;
77    Ret.LocVT = LocVT;
78    return Ret;
79  }
80
81  static CCValAssign getCustomReg(unsigned ValNo, MVT ValVT,
82                                  unsigned RegNo, MVT LocVT,
83                                  LocInfo HTP) {
84    CCValAssign Ret;
85    Ret = getReg(ValNo, ValVT, RegNo, LocVT, HTP);
86    Ret.isCustom = true;
87    return Ret;
88  }
89
90  static CCValAssign getMem(unsigned ValNo, MVT ValVT,
91                            unsigned Offset, MVT LocVT,
92                            LocInfo HTP) {
93    CCValAssign Ret;
94    Ret.ValNo = ValNo;
95    Ret.Loc = Offset;
96    Ret.isMem = true;
97    Ret.isCustom = false;
98    Ret.HTP = HTP;
99    Ret.ValVT = ValVT;
100    Ret.LocVT = LocVT;
101    return Ret;
102  }
103
104  static CCValAssign getCustomMem(unsigned ValNo, MVT ValVT,
105                                  unsigned Offset, MVT LocVT,
106                                  LocInfo HTP) {
107    CCValAssign Ret;
108    Ret = getMem(ValNo, ValVT, Offset, LocVT, HTP);
109    Ret.isCustom = true;
110    return Ret;
111  }
112
113  unsigned getValNo() const { return ValNo; }
114  MVT getValVT() const { return ValVT; }
115
116  bool isRegLoc() const { return !isMem; }
117  bool isMemLoc() const { return isMem; }
118
119  bool needsCustom() const { return isCustom; }
120
121  unsigned getLocReg() const { assert(isRegLoc()); return Loc; }
122  unsigned getLocMemOffset() const { assert(isMemLoc()); return Loc; }
123  MVT getLocVT() const { return LocVT; }
124
125  LocInfo getLocInfo() const { return HTP; }
126  bool isExtInLoc() const {
127    return (HTP == AExt || HTP == SExt || HTP == ZExt);
128  }
129
130};
131
132/// CCAssignFn - This function assigns a location for Val, updating State to
133/// reflect the change.  It returns 'true' if it failed to handle Val.
134typedef bool CCAssignFn(unsigned ValNo, MVT ValVT,
135                        MVT LocVT, CCValAssign::LocInfo LocInfo,
136                        ISD::ArgFlagsTy ArgFlags, CCState &State);
137
138/// CCCustomFn - This function assigns a location for Val, possibly updating
139/// all args to reflect changes and indicates if it handled it. It must set
140/// isCustom if it handles the arg and returns true.
141typedef bool CCCustomFn(unsigned &ValNo, MVT &ValVT,
142                        MVT &LocVT, CCValAssign::LocInfo &LocInfo,
143                        ISD::ArgFlagsTy &ArgFlags, CCState &State);
144
145/// ParmContext - This enum tracks whether calling convention lowering is in
146/// the context of prologue or call generation. Not all backends make use of
147/// this information.
148typedef enum { Unknown, Prologue, Call } ParmContext;
149
150/// CCState - This class holds information needed while lowering arguments and
151/// return values.  It captures which registers are already assigned and which
152/// stack slots are used.  It provides accessors to allocate these values.
153class CCState {
154private:
155  CallingConv::ID CallingConv;
156  bool IsVarArg;
157  MachineFunction &MF;
158  const TargetMachine &TM;
159  const TargetRegisterInfo &TRI;
160  SmallVector<CCValAssign, 16> &Locs;
161  LLVMContext &Context;
162
163  unsigned StackOffset;
164  SmallVector<uint32_t, 16> UsedRegs;
165  unsigned FirstByValReg;
166  bool FirstByValRegValid;
167
168protected:
169  ParmContext CallOrPrologue;
170
171public:
172  CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &MF,
173          const TargetMachine &TM, SmallVector<CCValAssign, 16> &locs,
174          LLVMContext &C);
175
176  void addLoc(const CCValAssign &V) {
177    Locs.push_back(V);
178  }
179
180  LLVMContext &getContext() const { return Context; }
181  const TargetMachine &getTarget() const { return TM; }
182  MachineFunction &getMachineFunction() const { return MF; }
183  CallingConv::ID getCallingConv() const { return CallingConv; }
184  bool isVarArg() const { return IsVarArg; }
185
186  unsigned getNextStackOffset() const { return StackOffset; }
187
188  /// isAllocated - Return true if the specified register (or an alias) is
189  /// allocated.
190  bool isAllocated(unsigned Reg) const {
191    return UsedRegs[Reg/32] & (1 << (Reg&31));
192  }
193
194  /// AnalyzeFormalArguments - Analyze an array of argument values,
195  /// incorporating info about the formals into this state.
196  void AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
197                              CCAssignFn Fn);
198
199  /// AnalyzeReturn - Analyze the returned values of a return,
200  /// incorporating info about the result values into this state.
201  void AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
202                     CCAssignFn Fn);
203
204  /// CheckReturn - Analyze the return values of a function, returning
205  /// true if the return can be performed without sret-demotion, and
206  /// false otherwise.
207  bool CheckReturn(const SmallVectorImpl<ISD::OutputArg> &ArgsFlags,
208                   CCAssignFn Fn);
209
210  /// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
211  /// incorporating info about the passed values into this state.
212  void AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
213                           CCAssignFn Fn);
214
215  /// AnalyzeCallOperands - Same as above except it takes vectors of types
216  /// and argument flags.
217  void AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
218                           SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
219                           CCAssignFn Fn);
220
221  /// AnalyzeCallResult - Analyze the return values of a call,
222  /// incorporating info about the passed values into this state.
223  void AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
224                         CCAssignFn Fn);
225
226  /// AnalyzeCallResult - Same as above except it's specialized for calls which
227  /// produce a single value.
228  void AnalyzeCallResult(MVT VT, CCAssignFn Fn);
229
230  /// getFirstUnallocated - Return the first unallocated register in the set, or
231  /// NumRegs if they are all allocated.
232  unsigned getFirstUnallocated(const uint16_t *Regs, unsigned NumRegs) const {
233    for (unsigned i = 0; i != NumRegs; ++i)
234      if (!isAllocated(Regs[i]))
235        return i;
236    return NumRegs;
237  }
238
239  /// AllocateReg - Attempt to allocate one register.  If it is not available,
240  /// return zero.  Otherwise, return the register, marking it and any aliases
241  /// as allocated.
242  unsigned AllocateReg(unsigned Reg) {
243    if (isAllocated(Reg)) return 0;
244    MarkAllocated(Reg);
245    return Reg;
246  }
247
248  /// Version of AllocateReg with extra register to be shadowed.
249  unsigned AllocateReg(unsigned Reg, unsigned ShadowReg) {
250    if (isAllocated(Reg)) return 0;
251    MarkAllocated(Reg);
252    MarkAllocated(ShadowReg);
253    return Reg;
254  }
255
256  /// AllocateReg - Attempt to allocate one of the specified registers.  If none
257  /// are available, return zero.  Otherwise, return the first one available,
258  /// marking it and any aliases as allocated.
259  unsigned AllocateReg(const uint16_t *Regs, unsigned NumRegs) {
260    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
261    if (FirstUnalloc == NumRegs)
262      return 0;    // Didn't find the reg.
263
264    // Mark the register and any aliases as allocated.
265    unsigned Reg = Regs[FirstUnalloc];
266    MarkAllocated(Reg);
267    return Reg;
268  }
269
270  /// Version of AllocateReg with list of registers to be shadowed.
271  unsigned AllocateReg(const uint16_t *Regs, const uint16_t *ShadowRegs,
272                       unsigned NumRegs) {
273    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
274    if (FirstUnalloc == NumRegs)
275      return 0;    // Didn't find the reg.
276
277    // Mark the register and any aliases as allocated.
278    unsigned Reg = Regs[FirstUnalloc], ShadowReg = ShadowRegs[FirstUnalloc];
279    MarkAllocated(Reg);
280    MarkAllocated(ShadowReg);
281    return Reg;
282  }
283
284  /// AllocateStack - Allocate a chunk of stack space with the specified size
285  /// and alignment.
286  unsigned AllocateStack(unsigned Size, unsigned Align) {
287    assert(Align && ((Align-1) & Align) == 0); // Align is power of 2.
288    StackOffset = ((StackOffset + Align-1) & ~(Align-1));
289    unsigned Result = StackOffset;
290    StackOffset += Size;
291    return Result;
292  }
293
294  /// Version of AllocateStack with extra register to be shadowed.
295  unsigned AllocateStack(unsigned Size, unsigned Align, unsigned ShadowReg) {
296    MarkAllocated(ShadowReg);
297    return AllocateStack(Size, Align);
298  }
299
300  // HandleByVal - Allocate a stack slot large enough to pass an argument by
301  // value. The size and alignment information of the argument is encoded in its
302  // parameter attribute.
303  void HandleByVal(unsigned ValNo, MVT ValVT,
304                   MVT LocVT, CCValAssign::LocInfo LocInfo,
305                   int MinSize, int MinAlign, ISD::ArgFlagsTy ArgFlags);
306
307  // First GPR that carries part of a byval aggregate that's split
308  // between registers and memory.
309  unsigned getFirstByValReg() const { return FirstByValRegValid ? FirstByValReg : 0; }
310  void setFirstByValReg(unsigned r) { FirstByValReg = r; FirstByValRegValid = true; }
311  void clearFirstByValReg() { FirstByValReg = 0; FirstByValRegValid = false; }
312  bool isFirstByValRegValid() const { return FirstByValRegValid; }
313
314  ParmContext getCallOrPrologue() const { return CallOrPrologue; }
315
316private:
317  /// MarkAllocated - Mark a register and all of its aliases as allocated.
318  void MarkAllocated(unsigned Reg);
319};
320
321
322
323} // end namespace llvm
324
325#endif
326