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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 
24 namespace llvm {
25   class TargetRegisterInfo;
26   class TargetMachine;
27   class CCState;
28 
29 /// CCValAssign - Represent assignment of one arg/retval to a location.
30 class CCValAssign {
31 public:
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   };
44 private:
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;
65 public:
66 
getReg(unsigned ValNo,MVT ValVT,unsigned RegNo,MVT LocVT,LocInfo HTP)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 
getCustomReg(unsigned ValNo,MVT ValVT,unsigned RegNo,MVT LocVT,LocInfo HTP)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 
getMem(unsigned ValNo,MVT ValVT,unsigned Offset,MVT LocVT,LocInfo HTP)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 
getCustomMem(unsigned ValNo,MVT ValVT,unsigned Offset,MVT LocVT,LocInfo HTP)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 
getValNo()113   unsigned getValNo() const { return ValNo; }
getValVT()114   MVT getValVT() const { return ValVT; }
115 
isRegLoc()116   bool isRegLoc() const { return !isMem; }
isMemLoc()117   bool isMemLoc() const { return isMem; }
118 
needsCustom()119   bool needsCustom() const { return isCustom; }
120 
getLocReg()121   unsigned getLocReg() const { assert(isRegLoc()); return Loc; }
getLocMemOffset()122   unsigned getLocMemOffset() const { assert(isMemLoc()); return Loc; }
getLocVT()123   MVT getLocVT() const { return LocVT; }
124 
getLocInfo()125   LocInfo getLocInfo() const { return HTP; }
isExtInLoc()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.
134 typedef 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.
141 typedef 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.
148 typedef 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.
153 class CCState {
154 private:
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 
168 protected:
169   ParmContext CallOrPrologue;
170 
171 public:
172   CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &MF,
173           const TargetMachine &TM, SmallVector<CCValAssign, 16> &locs,
174           LLVMContext &C);
175 
addLoc(const CCValAssign & V)176   void addLoc(const CCValAssign &V) {
177     Locs.push_back(V);
178   }
179 
getContext()180   LLVMContext &getContext() const { return Context; }
getTarget()181   const TargetMachine &getTarget() const { return TM; }
getMachineFunction()182   MachineFunction &getMachineFunction() const { return MF; }
getCallingConv()183   CallingConv::ID getCallingConv() const { return CallingConv; }
isVarArg()184   bool isVarArg() const { return IsVarArg; }
185 
getNextStackOffset()186   unsigned getNextStackOffset() const { return StackOffset; }
187 
188   /// isAllocated - Return true if the specified register (or an alias) is
189   /// allocated.
isAllocated(unsigned Reg)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.
getFirstUnallocated(const unsigned * Regs,unsigned NumRegs)232   unsigned getFirstUnallocated(const unsigned *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.
AllocateReg(unsigned Reg)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.
AllocateReg(unsigned Reg,unsigned ShadowReg)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.
AllocateReg(const unsigned * Regs,unsigned NumRegs)259   unsigned AllocateReg(const unsigned *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.
AllocateReg(const unsigned * Regs,const unsigned * ShadowRegs,unsigned NumRegs)271   unsigned AllocateReg(const unsigned *Regs, const unsigned *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.
AllocateStack(unsigned Size,unsigned Align)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.
AllocateStack(unsigned Size,unsigned Align,unsigned ShadowReg)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.
getFirstByValReg()309   unsigned getFirstByValReg() { return FirstByValRegValid ? FirstByValReg : 0; }
setFirstByValReg(unsigned r)310   void setFirstByValReg(unsigned r) { FirstByValReg = r; FirstByValRegValid = true; }
clearFirstByValReg()311   void clearFirstByValReg() { FirstByValReg = 0; FirstByValRegValid = false; }
isFirstByValRegValid()312   bool isFirstByValRegValid() { return FirstByValRegValid; }
313 
getCallOrPrologue()314   ParmContext getCallOrPrologue() { return CallOrPrologue; }
315 
316 private:
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