1 //=== X86CallingConv.cpp - X86 Custom Calling Convention Impl -*- 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 contains the implementation of custom routines for the X86 11 // Calling Convention that aren't done by tablegen. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "MCTargetDesc/X86MCTargetDesc.h" 16 #include "llvm/CodeGen/CallingConvLower.h" 17 #include "llvm/IR/CallingConv.h" 18 19 namespace llvm { 20 21 bool CC_X86_32_RegCall_Assign2Regs(unsigned &ValNo, MVT &ValVT, MVT &LocVT, 22 CCValAssign::LocInfo &LocInfo, 23 ISD::ArgFlagsTy &ArgFlags, CCState &State) { 24 // List of GPR registers that are available to store values in regcall 25 // calling convention. 26 static const MCPhysReg RegList[] = {X86::EAX, X86::ECX, X86::EDX, X86::EDI, 27 X86::ESI}; 28 29 // The vector will save all the available registers for allocation. 30 SmallVector<unsigned, 5> AvailableRegs; 31 32 // searching for the available registers. 33 for (auto Reg : RegList) { 34 if (!State.isAllocated(Reg)) 35 AvailableRegs.push_back(Reg); 36 } 37 38 const size_t RequiredGprsUponSplit = 2; 39 if (AvailableRegs.size() < RequiredGprsUponSplit) 40 return false; // Not enough free registers - continue the search. 41 42 // Allocating the available registers 43 for (unsigned I = 0; I < RequiredGprsUponSplit; I++) { 44 45 // Marking the register as located 46 unsigned Reg = State.AllocateReg(AvailableRegs[I]); 47 48 // Since we previously made sure that 2 registers are available 49 // we expect that a real register number will be returned 50 assert(Reg && "Expecting a register will be available"); 51 52 // Assign the value to the allocated register 53 State.addLoc(CCValAssign::getCustomReg(ValNo, ValVT, Reg, LocVT, LocInfo)); 54 } 55 56 // Successful in allocating regsiters - stop scanning next rules. 57 return true; 58 } 59 60 } // End llvm namespace 61