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/CodeGen/MachineRegisterInfo.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/SaveAndRestore.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include "llvm/Target/TargetLowering.h"
24 #include "llvm/Target/TargetRegisterInfo.h"
25 #include "llvm/Target/TargetSubtargetInfo.h"
26 using namespace llvm;
27
CCState(CallingConv::ID CC,bool isVarArg,MachineFunction & mf,SmallVectorImpl<CCValAssign> & locs,LLVMContext & C)28 CCState::CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &mf,
29 SmallVectorImpl<CCValAssign> &locs, LLVMContext &C)
30 : CallingConv(CC), IsVarArg(isVarArg), MF(mf),
31 TRI(*MF.getSubtarget().getRegisterInfo()), Locs(locs), Context(C),
32 CallOrPrologue(Unknown) {
33 // No stack is used.
34 StackOffset = 0;
35
36 clearByValRegsInfo();
37 UsedRegs.resize((TRI.getNumRegs()+31)/32);
38 }
39
40 // HandleByVal - Allocate space on the stack large enough to pass an argument
41 // by value. The size and alignment information of the argument is encoded in
42 // its parameter attribute.
HandleByVal(unsigned ValNo,MVT ValVT,MVT LocVT,CCValAssign::LocInfo LocInfo,int MinSize,int MinAlign,ISD::ArgFlagsTy ArgFlags)43 void CCState::HandleByVal(unsigned ValNo, MVT ValVT,
44 MVT LocVT, CCValAssign::LocInfo LocInfo,
45 int MinSize, int MinAlign,
46 ISD::ArgFlagsTy ArgFlags) {
47 unsigned Align = ArgFlags.getByValAlign();
48 unsigned Size = ArgFlags.getByValSize();
49 if (MinSize > (int)Size)
50 Size = MinSize;
51 if (MinAlign > (int)Align)
52 Align = MinAlign;
53 MF.getFrameInfo()->ensureMaxAlignment(Align);
54 MF.getSubtarget().getTargetLowering()->HandleByVal(this, Size, Align);
55 Size = unsigned(RoundUpToAlignment(Size, MinAlign));
56 unsigned Offset = AllocateStack(Size, Align);
57 addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
58 }
59
60 /// MarkAllocated - Mark a register and all of its aliases as allocated.
MarkAllocated(unsigned Reg)61 void CCState::MarkAllocated(unsigned Reg) {
62 for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
63 UsedRegs[*AI/32] |= 1 << (*AI&31);
64 }
65
66 /// AnalyzeFormalArguments - Analyze an array of argument values,
67 /// incorporating info about the formals into this state.
68 void
AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> & Ins,CCAssignFn Fn)69 CCState::AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
70 CCAssignFn Fn) {
71 unsigned NumArgs = Ins.size();
72
73 for (unsigned i = 0; i != NumArgs; ++i) {
74 MVT ArgVT = Ins[i].VT;
75 ISD::ArgFlagsTy ArgFlags = Ins[i].Flags;
76 if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
77 #ifndef NDEBUG
78 dbgs() << "Formal argument #" << i << " has unhandled type "
79 << EVT(ArgVT).getEVTString() << '\n';
80 #endif
81 llvm_unreachable(nullptr);
82 }
83 }
84 }
85
86 /// CheckReturn - Analyze the return values of a function, returning true if
87 /// the return can be performed without sret-demotion, and false otherwise.
CheckReturn(const SmallVectorImpl<ISD::OutputArg> & Outs,CCAssignFn Fn)88 bool CCState::CheckReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
89 CCAssignFn Fn) {
90 // Determine which register each value should be copied into.
91 for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
92 MVT VT = Outs[i].VT;
93 ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
94 if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
95 return false;
96 }
97 return true;
98 }
99
100 /// AnalyzeReturn - Analyze the returned values of a return,
101 /// incorporating info about the result values into this state.
AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> & Outs,CCAssignFn Fn)102 void CCState::AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
103 CCAssignFn Fn) {
104 // Determine which register each value should be copied into.
105 for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
106 MVT VT = Outs[i].VT;
107 ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
108 if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this)) {
109 #ifndef NDEBUG
110 dbgs() << "Return operand #" << i << " has unhandled type "
111 << EVT(VT).getEVTString() << '\n';
112 #endif
113 llvm_unreachable(nullptr);
114 }
115 }
116 }
117
118 /// AnalyzeCallOperands - Analyze the outgoing arguments to a call,
119 /// incorporating info about the passed values into this state.
AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> & Outs,CCAssignFn Fn)120 void CCState::AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
121 CCAssignFn Fn) {
122 unsigned NumOps = Outs.size();
123 for (unsigned i = 0; i != NumOps; ++i) {
124 MVT ArgVT = Outs[i].VT;
125 ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
126 if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
127 #ifndef NDEBUG
128 dbgs() << "Call operand #" << i << " has unhandled type "
129 << EVT(ArgVT).getEVTString() << '\n';
130 #endif
131 llvm_unreachable(nullptr);
132 }
133 }
134 }
135
136 /// AnalyzeCallOperands - Same as above except it takes vectors of types
137 /// and argument flags.
AnalyzeCallOperands(SmallVectorImpl<MVT> & ArgVTs,SmallVectorImpl<ISD::ArgFlagsTy> & Flags,CCAssignFn Fn)138 void CCState::AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
139 SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
140 CCAssignFn Fn) {
141 unsigned NumOps = ArgVTs.size();
142 for (unsigned i = 0; i != NumOps; ++i) {
143 MVT ArgVT = ArgVTs[i];
144 ISD::ArgFlagsTy ArgFlags = Flags[i];
145 if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
146 #ifndef NDEBUG
147 dbgs() << "Call operand #" << i << " has unhandled type "
148 << EVT(ArgVT).getEVTString() << '\n';
149 #endif
150 llvm_unreachable(nullptr);
151 }
152 }
153 }
154
155 /// AnalyzeCallResult - Analyze the return values of a call,
156 /// incorporating info about the passed values into this state.
AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> & Ins,CCAssignFn Fn)157 void CCState::AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
158 CCAssignFn Fn) {
159 for (unsigned i = 0, e = Ins.size(); i != e; ++i) {
160 MVT VT = Ins[i].VT;
161 ISD::ArgFlagsTy Flags = Ins[i].Flags;
162 if (Fn(i, VT, VT, CCValAssign::Full, Flags, *this)) {
163 #ifndef NDEBUG
164 dbgs() << "Call result #" << i << " has unhandled type "
165 << EVT(VT).getEVTString() << '\n';
166 #endif
167 llvm_unreachable(nullptr);
168 }
169 }
170 }
171
172 /// AnalyzeCallResult - Same as above except it's specialized for calls which
173 /// produce a single value.
AnalyzeCallResult(MVT VT,CCAssignFn Fn)174 void CCState::AnalyzeCallResult(MVT VT, CCAssignFn Fn) {
175 if (Fn(0, VT, VT, CCValAssign::Full, ISD::ArgFlagsTy(), *this)) {
176 #ifndef NDEBUG
177 dbgs() << "Call result has unhandled type "
178 << EVT(VT).getEVTString() << '\n';
179 #endif
180 llvm_unreachable(nullptr);
181 }
182 }
183
isValueTypeInRegForCC(CallingConv::ID CC,MVT VT)184 static bool isValueTypeInRegForCC(CallingConv::ID CC, MVT VT) {
185 if (VT.isVector())
186 return true; // Assume -msse-regparm might be in effect.
187 if (!VT.isInteger())
188 return false;
189 if (CC == CallingConv::X86_VectorCall || CC == CallingConv::X86_FastCall)
190 return true;
191 return false;
192 }
193
getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> & Regs,MVT VT,CCAssignFn Fn)194 void CCState::getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> &Regs,
195 MVT VT, CCAssignFn Fn) {
196 unsigned SavedStackOffset = StackOffset;
197 unsigned NumLocs = Locs.size();
198
199 // Set the 'inreg' flag if it is used for this calling convention.
200 ISD::ArgFlagsTy Flags;
201 if (isValueTypeInRegForCC(CallingConv, VT))
202 Flags.setInReg();
203
204 // Allocate something of this value type repeatedly until we get assigned a
205 // location in memory.
206 bool HaveRegParm = true;
207 while (HaveRegParm) {
208 if (Fn(0, VT, VT, CCValAssign::Full, Flags, *this)) {
209 #ifndef NDEBUG
210 dbgs() << "Call has unhandled type " << EVT(VT).getEVTString()
211 << " while computing remaining regparms\n";
212 #endif
213 llvm_unreachable(nullptr);
214 }
215 HaveRegParm = Locs.back().isRegLoc();
216 }
217
218 // Copy all the registers from the value locations we added.
219 assert(NumLocs < Locs.size() && "CC assignment failed to add location");
220 for (unsigned I = NumLocs, E = Locs.size(); I != E; ++I)
221 if (Locs[I].isRegLoc())
222 Regs.push_back(MCPhysReg(Locs[I].getLocReg()));
223
224 // Clear the assigned values and stack memory. We leave the registers marked
225 // as allocated so that future queries don't return the same registers, i.e.
226 // when i64 and f64 are both passed in GPRs.
227 StackOffset = SavedStackOffset;
228 Locs.resize(NumLocs);
229 }
230
analyzeMustTailForwardedRegisters(SmallVectorImpl<ForwardedRegister> & Forwards,ArrayRef<MVT> RegParmTypes,CCAssignFn Fn)231 void CCState::analyzeMustTailForwardedRegisters(
232 SmallVectorImpl<ForwardedRegister> &Forwards, ArrayRef<MVT> RegParmTypes,
233 CCAssignFn Fn) {
234 // Oftentimes calling conventions will not user register parameters for
235 // variadic functions, so we need to assume we're not variadic so that we get
236 // all the registers that might be used in a non-variadic call.
237 SaveAndRestore<bool> SavedVarArg(IsVarArg, false);
238
239 for (MVT RegVT : RegParmTypes) {
240 SmallVector<MCPhysReg, 8> RemainingRegs;
241 getRemainingRegParmsForType(RemainingRegs, RegVT, Fn);
242 const TargetLowering *TL = MF.getSubtarget().getTargetLowering();
243 const TargetRegisterClass *RC = TL->getRegClassFor(RegVT);
244 for (MCPhysReg PReg : RemainingRegs) {
245 unsigned VReg = MF.addLiveIn(PReg, RC);
246 Forwards.push_back(ForwardedRegister(VReg, PReg, RegVT));
247 }
248 }
249 }
250