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/IR/DataLayout.h"
18 #include "llvm/Support/Debug.h"
19 #include "llvm/Support/ErrorHandling.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include "llvm/Target/TargetLowering.h"
22 #include "llvm/Target/TargetMachine.h"
23 #include "llvm/Target/TargetRegisterInfo.h"
24 #include "llvm/Target/TargetSubtargetInfo.h"
25 using namespace llvm;
26 
27 CCState::CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &mf,
28                  SmallVectorImpl<CCValAssign> &locs, LLVMContext &C)
29     : CallingConv(CC), IsVarArg(isVarArg), MF(mf),
30       TRI(*MF.getSubtarget().getRegisterInfo()), Locs(locs), Context(C),
31       CallOrPrologue(Unknown) {
32   // No stack is used.
33   StackOffset = 0;
34 
35   clearByValRegsInfo();
36   UsedRegs.resize((TRI.getNumRegs()+31)/32);
37 }
38 
39 // HandleByVal - Allocate space on the stack large enough to pass an argument
40 // by value. The size and alignment information of the argument is encoded in
41 // its parameter attribute.
42 void CCState::HandleByVal(unsigned ValNo, MVT ValVT,
43                           MVT LocVT, CCValAssign::LocInfo LocInfo,
44                           int MinSize, int MinAlign,
45                           ISD::ArgFlagsTy ArgFlags) {
46   unsigned Align = ArgFlags.getByValAlign();
47   unsigned Size  = ArgFlags.getByValSize();
48   if (MinSize > (int)Size)
49     Size = MinSize;
50   if (MinAlign > (int)Align)
51     Align = MinAlign;
52   MF.getFrameInfo()->ensureMaxAlignment(Align);
53   MF.getSubtarget().getTargetLowering()->HandleByVal(this, Size, Align);
54   Size = unsigned(RoundUpToAlignment(Size, MinAlign));
55   unsigned Offset = AllocateStack(Size, Align);
56   addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
57 }
58 
59 /// MarkAllocated - Mark a register and all of its aliases as allocated.
60 void CCState::MarkAllocated(unsigned Reg) {
61   for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
62     UsedRegs[*AI/32] |= 1 << (*AI&31);
63 }
64 
65 /// AnalyzeFormalArguments - Analyze an array of argument values,
66 /// incorporating info about the formals into this state.
67 void
68 CCState::AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
69                                 CCAssignFn Fn) {
70   unsigned NumArgs = Ins.size();
71 
72   for (unsigned i = 0; i != NumArgs; ++i) {
73     MVT ArgVT = Ins[i].VT;
74     ISD::ArgFlagsTy ArgFlags = Ins[i].Flags;
75     if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
76 #ifndef NDEBUG
77       dbgs() << "Formal argument #" << i << " has unhandled type "
78              << EVT(ArgVT).getEVTString() << '\n';
79 #endif
80       llvm_unreachable(nullptr);
81     }
82   }
83 }
84 
85 /// CheckReturn - Analyze the return values of a function, returning true if
86 /// the return can be performed without sret-demotion, and false otherwise.
87 bool CCState::CheckReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
88                           CCAssignFn Fn) {
89   // Determine which register each value should be copied into.
90   for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
91     MVT VT = Outs[i].VT;
92     ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
93     if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
94       return false;
95   }
96   return true;
97 }
98 
99 /// AnalyzeReturn - Analyze the returned values of a return,
100 /// incorporating info about the result values into this state.
101 void CCState::AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
102                             CCAssignFn Fn) {
103   // Determine which register each value should be copied into.
104   for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
105     MVT VT = Outs[i].VT;
106     ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
107     if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this)) {
108 #ifndef NDEBUG
109       dbgs() << "Return operand #" << i << " has unhandled type "
110              << EVT(VT).getEVTString() << '\n';
111 #endif
112       llvm_unreachable(nullptr);
113     }
114   }
115 }
116 
117 /// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
118 /// incorporating info about the passed values into this state.
119 void CCState::AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
120                                   CCAssignFn Fn) {
121   unsigned NumOps = Outs.size();
122   for (unsigned i = 0; i != NumOps; ++i) {
123     MVT ArgVT = Outs[i].VT;
124     ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
125     if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
126 #ifndef NDEBUG
127       dbgs() << "Call operand #" << i << " has unhandled type "
128              << EVT(ArgVT).getEVTString() << '\n';
129 #endif
130       llvm_unreachable(nullptr);
131     }
132   }
133 }
134 
135 /// AnalyzeCallOperands - Same as above except it takes vectors of types
136 /// and argument flags.
137 void CCState::AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
138                                   SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
139                                   CCAssignFn Fn) {
140   unsigned NumOps = ArgVTs.size();
141   for (unsigned i = 0; i != NumOps; ++i) {
142     MVT ArgVT = ArgVTs[i];
143     ISD::ArgFlagsTy ArgFlags = Flags[i];
144     if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
145 #ifndef NDEBUG
146       dbgs() << "Call operand #" << i << " has unhandled type "
147              << EVT(ArgVT).getEVTString() << '\n';
148 #endif
149       llvm_unreachable(nullptr);
150     }
151   }
152 }
153 
154 /// AnalyzeCallResult - Analyze the return values of a call,
155 /// incorporating info about the passed values into this state.
156 void CCState::AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
157                                 CCAssignFn Fn) {
158   for (unsigned i = 0, e = Ins.size(); i != e; ++i) {
159     MVT VT = Ins[i].VT;
160     ISD::ArgFlagsTy Flags = Ins[i].Flags;
161     if (Fn(i, VT, VT, CCValAssign::Full, Flags, *this)) {
162 #ifndef NDEBUG
163       dbgs() << "Call result #" << i << " has unhandled type "
164              << EVT(VT).getEVTString() << '\n';
165 #endif
166       llvm_unreachable(nullptr);
167     }
168   }
169 }
170 
171 /// AnalyzeCallResult - Same as above except it's specialized for calls which
172 /// produce a single value.
173 void CCState::AnalyzeCallResult(MVT VT, CCAssignFn Fn) {
174   if (Fn(0, VT, VT, CCValAssign::Full, ISD::ArgFlagsTy(), *this)) {
175 #ifndef NDEBUG
176     dbgs() << "Call result has unhandled type "
177            << EVT(VT).getEVTString() << '\n';
178 #endif
179     llvm_unreachable(nullptr);
180   }
181 }
182