lib/CodeGen/CallingConvLower.cpp

   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/CodeGen/TargetLowering.h"
  19 #include "llvm/CodeGen/TargetRegisterInfo.h"
  20 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  21 #include "llvm/IR/DataLayout.h"
  22 #include "llvm/Support/Debug.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 #include "llvm/Support/SaveAndRestore.h"
  25 #include "llvm/Support/raw_ostream.h"
  26 #include <algorithm>
  27
  28 using namespace llvm;
  29
  30 CCState::CCState(CallingConv::ID CC, bool isVarArg, MachineFunction &mf,
  31                  SmallVectorImpl<CCValAssign> &locs, LLVMContext &C)
  32     : CallingConv(CC), IsVarArg(isVarArg), MF(mf),
  33       TRI(*MF.getSubtarget().getRegisterInfo()), Locs(locs), Context(C) {
  34   // No stack is used.
  35   StackOffset = 0;
  36   MaxStackArgAlign = 1;
  37
  38   clearByValRegsInfo();
  39   UsedRegs.resize((TRI.getNumRegs()+31)/32);
  40 }
  41
  42 /// Allocate space on the stack large enough to pass an argument by value.
  43 /// The size and alignment information of the argument is encoded in
  44 /// its parameter attribute.
  45 void CCState::HandleByVal(unsigned ValNo, MVT ValVT,
  46                           MVT LocVT, CCValAssign::LocInfo LocInfo,
  47                           int MinSize, int MinAlign,
  48                           ISD::ArgFlagsTy ArgFlags) {
  49   unsigned Align = ArgFlags.getByValAlign();
  50   unsigned Size  = ArgFlags.getByValSize();
  51   if (MinSize > (int)Size)
  52     Size = MinSize;
  53   if (MinAlign > (int)Align)
  54     Align = MinAlign;
  55   ensureMaxAlignment(Align);
  56   MF.getSubtarget().getTargetLowering()->HandleByVal(this, Size, Align);
  57   Size = unsigned(alignTo(Size, MinAlign));
  58   unsigned Offset = AllocateStack(Size, Align);
  59   addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
  60 }
  61
  62 /// Mark a register and all of its aliases as allocated.
  63 void CCState::MarkAllocated(unsigned Reg) {
  64   for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
  65     UsedRegs[*AI/32] |= 1 << (*AI&31);
  66 }
  67
  68 bool CCState::IsShadowAllocatedReg(unsigned Reg) const {
  69   if (!isAllocated(Reg))
  70     return false;
  71
  72   for (auto const &ValAssign : Locs) {
  73     if (ValAssign.isRegLoc()) {
  74       for (MCRegAliasIterator AI(ValAssign.getLocReg(), &TRI, true);
  75            AI.isValid(); ++AI) {
  76         if (*AI == Reg)
  77           return false;
  78       }
  79     }
  80   }
  81   return true;
  82 }
  83
  84 /// Analyze an array of argument values,
  85 /// incorporating info about the formals into this state.
  86 void
  87 CCState::AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
  88                                 CCAssignFn Fn) {
  89   unsigned NumArgs = Ins.size();
  90
  91   for (unsigned i = 0; i != NumArgs; ++i) {
  92     MVT ArgVT = Ins[i].VT;
  93     ISD::ArgFlagsTy ArgFlags = Ins[i].Flags;
  94     if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
  95 #ifndef NDEBUG
  96       dbgs() << "Formal argument #" << i << " has unhandled type "
  97              << EVT(ArgVT).getEVTString() << '\n';
  98 #endif
  99       llvm_unreachable(nullptr);
 100     }
 101   }
 102 }
 103
 104 /// Analyze the return values of a function, returning true if the return can
 105 /// be performed without sret-demotion and false otherwise.
 106 bool CCState::CheckReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
 107                           CCAssignFn Fn) {
 108   // Determine which register each value should be copied into.
 109   for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
 110     MVT VT = Outs[i].VT;
 111     ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
 112     if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
 113       return false;
 114   }
 115   return true;
 116 }
 117
 118 /// Analyze the returned values of a return,
 119 /// incorporating info about the result values into this state.
 120 void CCState::AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
 121                             CCAssignFn Fn) {
 122   // Determine which register each value should be copied into.
 123   for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
 124     MVT VT = Outs[i].VT;
 125     ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
 126     if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this)) {
 127 #ifndef NDEBUG
 128       dbgs() << "Return operand #" << i << " has unhandled type "
 129              << EVT(VT).getEVTString() << '\n';
 130 #endif
 131       llvm_unreachable(nullptr);
 132     }
 133   }
 134 }
 135
 136 /// Analyze the outgoing arguments to a call,
 137 /// incorporating info about the passed values into this state.
 138 void CCState::AnalyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
 139                                   CCAssignFn Fn) {
 140   unsigned NumOps = Outs.size();
 141   for (unsigned i = 0; i != NumOps; ++i) {
 142     MVT ArgVT = Outs[i].VT;
 143     ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
 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 /// Same as above except it takes vectors of types and argument flags.
 155 void CCState::AnalyzeCallOperands(SmallVectorImpl<MVT> &ArgVTs,
 156                                   SmallVectorImpl<ISD::ArgFlagsTy> &Flags,
 157                                   CCAssignFn Fn) {
 158   unsigned NumOps = ArgVTs.size();
 159   for (unsigned i = 0; i != NumOps; ++i) {
 160     MVT ArgVT = ArgVTs[i];
 161     ISD::ArgFlagsTy ArgFlags = Flags[i];
 162     if (Fn(i, ArgVT, ArgVT, CCValAssign::Full, ArgFlags, *this)) {
 163 #ifndef NDEBUG
 164       dbgs() << "Call operand #" << i << " has unhandled type "
 165              << EVT(ArgVT).getEVTString() << '\n';
 166 #endif
 167       llvm_unreachable(nullptr);
 168     }
 169   }
 170 }
 171
 172 /// Analyze the return values of a call, incorporating info about the passed
 173 /// values into this state.
 174 void CCState::AnalyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
 175                                 CCAssignFn Fn) {
 176   for (unsigned i = 0, e = Ins.size(); i != e; ++i) {
 177     MVT VT = Ins[i].VT;
 178     ISD::ArgFlagsTy Flags = Ins[i].Flags;
 179     if (Fn(i, VT, VT, CCValAssign::Full, Flags, *this)) {
 180 #ifndef NDEBUG
 181       dbgs() << "Call result #" << i << " has unhandled type "
 182              << EVT(VT).getEVTString() << '\n';
 183 #endif
 184       llvm_unreachable(nullptr);
 185     }
 186   }
 187 }
 188
 189 /// Same as above except it's specialized for calls that produce a single value.
 190 void CCState::AnalyzeCallResult(MVT VT, CCAssignFn Fn) {
 191   if (Fn(0, VT, VT, CCValAssign::Full, ISD::ArgFlagsTy(), *this)) {
 192 #ifndef NDEBUG
 193     dbgs() << "Call result has unhandled type "
 194            << EVT(VT).getEVTString() << '\n';
 195 #endif
 196     llvm_unreachable(nullptr);
 197   }
 198 }
 199
 200 static bool isValueTypeInRegForCC(CallingConv::ID CC, MVT VT) {
 201   if (VT.isVector())
 202     return true; // Assume -msse-regparm might be in effect.
 203   if (!VT.isInteger())
 204     return false;
 205   if (CC == CallingConv::X86_VectorCall || CC == CallingConv::X86_FastCall)
 206     return true;
 207   return false;
 208 }
 209
 210 void CCState::getRemainingRegParmsForType(SmallVectorImpl<MCPhysReg> &Regs,
 211                                           MVT VT, CCAssignFn Fn) {
 212   unsigned SavedStackOffset = StackOffset;
 213   unsigned SavedMaxStackArgAlign = MaxStackArgAlign;
 214   unsigned NumLocs = Locs.size();
 215
 216   // Set the 'inreg' flag if it is used for this calling convention.
 217   ISD::ArgFlagsTy Flags;
 218   if (isValueTypeInRegForCC(CallingConv, VT))
 219     Flags.setInReg();
 220
 221   // Allocate something of this value type repeatedly until we get assigned a
 222   // location in memory.
 223   bool HaveRegParm = true;
 224   while (HaveRegParm) {
 225     if (Fn(0, VT, VT, CCValAssign::Full, Flags, *this)) {
 226 #ifndef NDEBUG
 227       dbgs() << "Call has unhandled type " << EVT(VT).getEVTString()
 228              << " while computing remaining regparms\n";
 229 #endif
 230       llvm_unreachable(nullptr);
 231     }
 232     HaveRegParm = Locs.back().isRegLoc();
 233   }
 234
 235   // Copy all the registers from the value locations we added.
 236   assert(NumLocs < Locs.size() && "CC assignment failed to add location");
 237   for (unsigned I = NumLocs, E = Locs.size(); I != E; ++I)
 238     if (Locs[I].isRegLoc())
 239       Regs.push_back(MCPhysReg(Locs[I].getLocReg()));
 240
 241   // Clear the assigned values and stack memory. We leave the registers marked
 242   // as allocated so that future queries don't return the same registers, i.e.
 243   // when i64 and f64 are both passed in GPRs.
 244   StackOffset = SavedStackOffset;
 245   MaxStackArgAlign = SavedMaxStackArgAlign;
 246   Locs.resize(NumLocs);
 247 }
 248
 249 void CCState::analyzeMustTailForwardedRegisters(
 250     SmallVectorImpl<ForwardedRegister> &Forwards, ArrayRef<MVT> RegParmTypes,
 251     CCAssignFn Fn) {
 252   // Oftentimes calling conventions will not user register parameters for
 253   // variadic functions, so we need to assume we're not variadic so that we get
 254   // all the registers that might be used in a non-variadic call.
 255   SaveAndRestore<bool> SavedVarArg(IsVarArg, false);
 256   SaveAndRestore<bool> SavedMustTail(AnalyzingMustTailForwardedRegs, true);
 257
 258   for (MVT RegVT : RegParmTypes) {
 259     SmallVector<MCPhysReg, 8> RemainingRegs;
 260     getRemainingRegParmsForType(RemainingRegs, RegVT, Fn);
 261     const TargetLowering *TL = MF.getSubtarget().getTargetLowering();
 262     const TargetRegisterClass *RC = TL->getRegClassFor(RegVT);
 263     for (MCPhysReg PReg : RemainingRegs) {
 264       unsigned VReg = MF.addLiveIn(PReg, RC);
 265       Forwards.push_back(ForwardedRegister(VReg, PReg, RegVT));
 266     }
 267   }
 268 }
 269
 270 bool CCState::resultsCompatible(CallingConv::ID CalleeCC,
 271                                 CallingConv::ID CallerCC, MachineFunction &MF,
 272                                 LLVMContext &C,
 273                                 const SmallVectorImpl<ISD::InputArg> &Ins,
 274                                 CCAssignFn CalleeFn, CCAssignFn CallerFn) {
 275   if (CalleeCC == CallerCC)
 276     return true;
 277   SmallVector<CCValAssign, 4> RVLocs1;
 278   CCState CCInfo1(CalleeCC, false, MF, RVLocs1, C);
 279   CCInfo1.AnalyzeCallResult(Ins, CalleeFn);
 280
 281   SmallVector<CCValAssign, 4> RVLocs2;
 282   CCState CCInfo2(CallerCC, false, MF, RVLocs2, C);
 283   CCInfo2.AnalyzeCallResult(Ins, CallerFn);
 284
 285   if (RVLocs1.size() != RVLocs2.size())
 286     return false;
 287   for (unsigned I = 0, E = RVLocs1.size(); I != E; ++I) {
 288     const CCValAssign &Loc1 = RVLocs1[I];
 289     const CCValAssign &Loc2 = RVLocs2[I];
 290     if (Loc1.getLocInfo() != Loc2.getLocInfo())
 291       return false;
 292     bool RegLoc1 = Loc1.isRegLoc();
 293     if (RegLoc1 != Loc2.isRegLoc())
 294       return false;
 295     if (RegLoc1) {
 296       if (Loc1.getLocReg() != Loc2.getLocReg())
 297         return false;
 298     } else {
 299       if (Loc1.getLocMemOffset() != Loc2.getLocMemOffset())
 300         return false;
 301     }
 302   }
 303   return true;
 304 }