llvm/lib/Support/ARMWinEH.cpp

   1 //===-- ARMWinEH.cpp - Windows on ARM EH Support Functions ------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Support/ARMWinEH.h"
  10
  11 namespace llvm {
  12 namespace ARM {
  13 namespace WinEH {
  14 std::pair<uint16_t, uint32_t> SavedRegisterMask(const RuntimeFunction &RF,
  15                                                 bool Prologue) {
  16   uint8_t NumRegisters = RF.Reg();
  17   uint8_t RegistersVFP = RF.R();
  18   uint8_t LinkRegister = RF.L();
  19   uint8_t ChainedFrame = RF.C();
  20
  21   uint16_t GPRMask = (ChainedFrame << 11);
  22   uint32_t VFPMask = 0;
  23
  24   if (Prologue) {
  25     GPRMask |= (LinkRegister << 14);
  26   } else {
  27     // If Ret != 0, we pop into Lr and return later
  28     if (RF.Ret() != ReturnType::RT_POP)
  29       GPRMask |= (LinkRegister << 14);
  30     else if (!RF.H()) // If H == 0, we pop directly into Pc
  31       GPRMask |= (LinkRegister << 15);
  32     // else, Ret == 0 && H == 1, we pop into Pc separately afterwards
  33   }
  34
  35   if (RegistersVFP)
  36     VFPMask |= (((1 << ((NumRegisters + 1) % 8)) - 1) << 8);
  37   else
  38     GPRMask |= (((1 << (NumRegisters + 1)) - 1) << 4);
  39
  40   if ((PrologueFolding(RF) && Prologue) || (EpilogueFolding(RF) && !Prologue))
  41     GPRMask |= (((1 << ((RF.StackAdjust() & 0x3) + 1)) - 1)
  42                 << (~RF.StackAdjust() & 0x3));
  43
  44   return std::make_pair(GPRMask, VFPMask);
  45 }
  46 } // namespace WinEH
  47 } // namespace ARM
  48 } // namespace llvm
  49