CallingConvLower.h revision 210299 
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/ValueTypes.h"
20#include "llvm/Target/TargetCallingConv.h"
21#include "llvm/CallingConv.h"
22
23namespace llvm {
24  class TargetRegisterInfo;
25  class TargetMachine;
26  class CCState;
27
28/// CCValAssign - Represent assignment of one arg/retval to a location.
29class CCValAssign {
30public:
31  enum LocInfo {
32    Full,   // The value fills the full location.
33    SExt,   // The value is sign extended in the location.
34    ZExt,   // The value is zero extended in the location.
35    AExt,   // The value is extended with undefined upper bits.
36    BCvt,   // The value is bit-converted in the location.
37    VExt,   // The value is vector-widened in the location.
38            // FIXME: Not implemented yet. Code that uses AExt to mean
39            // vector-widen should be fixed to use VExt instead.
40    Indirect // The location contains pointer to the value.
41    // TODO: a subset of the value is in the location.
42  };
43private:
44  /// ValNo - This is the value number begin assigned (e.g. an argument number).
45  unsigned ValNo;
46
47  /// Loc is either a stack offset or a register number.
48  unsigned Loc;
49
50  /// isMem - True if this is a memory loc, false if it is a register loc.
51  bool isMem : 1;
52
53  /// isCustom - True if this arg/retval requires special handling.
54  bool isCustom : 1;
55
56  /// Information about how the value is assigned.
57  LocInfo HTP : 6;
58
59  /// ValVT - The type of the value being assigned.
60  EVT ValVT;
61
62  /// LocVT - The type of the location being assigned to.
63  EVT LocVT;
64public:
65
66  static CCValAssign getReg(unsigned ValNo, EVT ValVT,
67                            unsigned RegNo, EVT LocVT,
68                            LocInfo HTP) {
69    CCValAssign Ret;
70    Ret.ValNo = ValNo;
71    Ret.Loc = RegNo;
72    Ret.isMem = false;
73    Ret.isCustom = false;
74    Ret.HTP = HTP;
75    Ret.ValVT = ValVT;
76    Ret.LocVT = LocVT;
77    return Ret;
78  }
79
80  static CCValAssign getCustomReg(unsigned ValNo, EVT ValVT,
81                                  unsigned RegNo, EVT LocVT,
82                                  LocInfo HTP) {
83    CCValAssign Ret;
84    Ret = getReg(ValNo, ValVT, RegNo, LocVT, HTP);
85    Ret.isCustom = true;
86    return Ret;
87  }
88
89  static CCValAssign getMem(unsigned ValNo, EVT ValVT,
90                            unsigned Offset, EVT LocVT,
91                            LocInfo HTP) {
92    CCValAssign Ret;
93    Ret.ValNo = ValNo;
94    Ret.Loc = Offset;
95    Ret.isMem = true;
96    Ret.isCustom = false;
97    Ret.HTP = HTP;
98    Ret.ValVT = ValVT;
99    Ret.LocVT = LocVT;
100    return Ret;
101  }
102
103  static CCValAssign getCustomMem(unsigned ValNo, EVT ValVT,
104                                  unsigned Offset, EVT LocVT,
105                                  LocInfo HTP) {
106    CCValAssign Ret;
107    Ret = getMem(ValNo, ValVT, Offset, LocVT, HTP);
108    Ret.isCustom = true;
109    return Ret;
110  }
111
112  unsigned getValNo() const { return ValNo; }
113  EVT getValVT() const { return ValVT; }
114
115  bool isRegLoc() const { return !isMem; }
116  bool isMemLoc() const { return isMem; }
117
118  bool needsCustom() const { return isCustom; }
119
120  unsigned getLocReg() const { assert(isRegLoc()); return Loc; }
121  unsigned getLocMemOffset() const { assert(isMemLoc()); return Loc; }
122  EVT getLocVT() const { return LocVT; }
123
124  LocInfo getLocInfo() const { return HTP; }
125  bool isExtInLoc() const {
126    return (HTP == AExt || HTP == SExt || HTP == ZExt);
127  }
128
129};
130
131/// CCAssignFn - This function assigns a location for Val, updating State to
132/// reflect the change.
133typedef bool CCAssignFn(unsigned ValNo, EVT ValVT,
134                        EVT LocVT, CCValAssign::LocInfo LocInfo,
135                        ISD::ArgFlagsTy ArgFlags, CCState &State);
136
137/// CCCustomFn - This function assigns a location for Val, possibly updating
138/// all args to reflect changes and indicates if it handled it. It must set
139/// isCustom if it handles the arg and returns true.
140typedef bool CCCustomFn(unsigned &ValNo, EVT &ValVT,
141                        EVT &LocVT, CCValAssign::LocInfo &LocInfo,
142                        ISD::ArgFlagsTy &ArgFlags, CCState &State);
143
144/// CCState - This class holds information needed while lowering arguments and
145/// return values.  It captures which registers are already assigned and which
146/// stack slots are used.  It provides accessors to allocate these values.
147class CCState {
148  CallingConv::ID CallingConv;
149  bool IsVarArg;
150  const TargetMachine &TM;
151  const TargetRegisterInfo &TRI;
152  SmallVector<CCValAssign, 16> &Locs;
153  LLVMContext &Context;
154
155  unsigned StackOffset;
156  SmallVector<uint32_t, 16> UsedRegs;
157public:
158  CCState(CallingConv::ID CC, bool isVarArg, const TargetMachine &TM,
159          SmallVector<CCValAssign, 16> &locs, LLVMContext &C);
160
161  void addLoc(const CCValAssign &V) {
162    Locs.push_back(V);
163  }
164
165  LLVMContext &getContext() const { return Context; }
166  const TargetMachine &getTarget() const { return TM; }
167  CallingConv::ID getCallingConv() const { return CallingConv; }
168  bool isVarArg() const { return IsVarArg; }
169
170  unsigned getNextStackOffset() const { return StackOffset; }
171
172  /// isAllocated - Return true if the specified register (or an alias) is
173  /// allocated.
174  bool isAllocated(unsigned Reg) const {
175    return UsedRegs[Reg/32] & (1 << (Reg&31));
176  }
177
178  /// AnalyzeFormalArguments - Analyze an array of argument values,
179  /// incorporating info about the formals into this state.
180  void AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
181                              CCAssignFn Fn);
182
183  /// AnalyzeReturn - Analyze the returned values of a return,
184  /// incorporating info about the result values into this state.
185  void AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
186                     CCAssignFn Fn);
187
188  /// CheckReturn - Analyze the return values of a function, returning
189  /// true if the return can be performed without sret-demotion, and
190  /// false otherwise.
191  bool CheckReturn(const SmallVectorImpl<ISD::OutputArg> &ArgsFlags,
192                   CCAssignFn Fn);
193
194  /// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
195  /// incorporating info about the passed values into this state.
196  void AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
197                           CCAssignFn Fn);
198
199  /// AnalyzeCallOperands - Same as above except it takes vectors of types
200  /// and argument flags.
201  void AnalyzeCallOperands(SmallVectorImpl<EVT> &ArgVTs,
202                           SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
203                           CCAssignFn Fn);
204
205  /// AnalyzeCallResult - Analyze the return values of a call,
206  /// incorporating info about the passed values into this state.
207  void AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
208                         CCAssignFn Fn);
209
210  /// AnalyzeCallResult - Same as above except it's specialized for calls which
211  /// produce a single value.
212  void AnalyzeCallResult(EVT VT, CCAssignFn Fn);
213
214  /// getFirstUnallocated - Return the first unallocated register in the set, or
215  /// NumRegs if they are all allocated.
216  unsigned getFirstUnallocated(const unsigned *Regs, unsigned NumRegs) const {
217    for (unsigned i = 0; i != NumRegs; ++i)
218      if (!isAllocated(Regs[i]))
219        return i;
220    return NumRegs;
221  }
222
223  /// AllocateReg - Attempt to allocate one register.  If it is not available,
224  /// return zero.  Otherwise, return the register, marking it and any aliases
225  /// as allocated.
226  unsigned AllocateReg(unsigned Reg) {
227    if (isAllocated(Reg)) return 0;
228    MarkAllocated(Reg);
229    return Reg;
230  }
231
232  /// Version of AllocateReg with extra register to be shadowed.
233  unsigned AllocateReg(unsigned Reg, unsigned ShadowReg) {
234    if (isAllocated(Reg)) return 0;
235    MarkAllocated(Reg);
236    MarkAllocated(ShadowReg);
237    return Reg;
238  }
239
240  /// AllocateReg - Attempt to allocate one of the specified registers.  If none
241  /// are available, return zero.  Otherwise, return the first one available,
242  /// marking it and any aliases as allocated.
243  unsigned AllocateReg(const unsigned *Regs, unsigned NumRegs) {
244    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
245    if (FirstUnalloc == NumRegs)
246      return 0;    // Didn't find the reg.
247
248    // Mark the register and any aliases as allocated.
249    unsigned Reg = Regs[FirstUnalloc];
250    MarkAllocated(Reg);
251    return Reg;
252  }
253
254  /// Version of AllocateReg with list of registers to be shadowed.
255  unsigned AllocateReg(const unsigned *Regs, const unsigned *ShadowRegs,
256                       unsigned NumRegs) {
257    unsigned FirstUnalloc = getFirstUnallocated(Regs, NumRegs);
258    if (FirstUnalloc == NumRegs)
259      return 0;    // Didn't find the reg.
260
261    // Mark the register and any aliases as allocated.
262    unsigned Reg = Regs[FirstUnalloc], ShadowReg = ShadowRegs[FirstUnalloc];
263    MarkAllocated(Reg);
264    MarkAllocated(ShadowReg);
265    return Reg;
266  }
267
268  /// AllocateStack - Allocate a chunk of stack space with the specified size
269  /// and alignment.
270  unsigned AllocateStack(unsigned Size, unsigned Align) {
271    assert(Align && ((Align-1) & Align) == 0); // Align is power of 2.
272    StackOffset = ((StackOffset + Align-1) & ~(Align-1));
273    unsigned Result = StackOffset;
274    StackOffset += Size;
275    return Result;
276  }
277
278  // HandleByVal - Allocate a stack slot large enough to pass an argument by
279  // value. The size and alignment information of the argument is encoded in its
280  // parameter attribute.
281  void HandleByVal(unsigned ValNo, EVT ValVT,
282                   EVT LocVT, CCValAssign::LocInfo LocInfo,
283                   int MinSize, int MinAlign, ISD::ArgFlagsTy ArgFlags);
284
285private:
286  /// MarkAllocated - Mark a register and all of its aliases as allocated.
287  void MarkAllocated(unsigned Reg);
288};
289
290
291
292} // end namespace llvm
293
294#endif
295