lib/Target/PowerPC/PPCFrameInfo.h

   1 //===-- PPCFrameInfo.h - Define TargetFrameInfo for PowerPC -----*- 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 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef POWERPC_FRAMEINFO_H
  14 #define POWERPC_FRAMEINFO_H
  15
  16 #include "PPC.h"
  17 #include "llvm/Target/TargetFrameInfo.h"
  18 #include "llvm/Target/TargetMachine.h"
  19
  20 namespace llvm {
  21
  22 class PPCFrameInfo: public TargetFrameInfo {
  23   const TargetMachine &TM;
  24
  25 public:
  26   PPCFrameInfo(const TargetMachine &tm, bool LP64)
  27     : TargetFrameInfo(TargetFrameInfo::StackGrowsDown, 16, 0), TM(tm) {
  28   }
  29
  30   /// getReturnSaveOffset - Return the previous frame offset to save the
  31   /// return address.
  32   static unsigned getReturnSaveOffset(bool LP64, bool isMacho) {
  33     if (isMacho)
  34       return LP64 ? 16 : 8;
  35     // For ELF 32 ABI:
  36     return 4;
  37   }
  38
  39   /// getFramePointerSaveOffset - Return the previous frame offset to save the
  40   /// frame pointer.
  41   static unsigned getFramePointerSaveOffset(bool LP64, bool isMacho) {
  42     // For MachO ABI:
  43     // Use the TOC save slot in the PowerPC linkage area for saving the frame
  44     // pointer (if needed.)  LLVM does not generate code that uses the TOC (R2
  45     // is treated as a caller saved register.)
  46     if (isMacho)
  47       return LP64 ? 40 : 20;
  48
  49     // For ELF 32 ABI:
  50     // Save it right before the link register
  51     return -4U;
  52   }
  53
  54   /// getLinkageSize - Return the size of the PowerPC ABI linkage area.
  55   ///
  56   static unsigned getLinkageSize(bool LP64, bool isMacho) {
  57     if (isMacho)
  58       return 6 * (LP64 ? 8 : 4);
  59
  60     // For ELF 32 ABI:
  61     return 8;
  62   }
  63
  64   /// getMinCallArgumentsSize - Return the size of the minium PowerPC ABI
  65   /// argument area.
  66   static unsigned getMinCallArgumentsSize(bool LP64, bool isMacho) {
  67     // For Macho ABI:
  68     // The prolog code of the callee may store up to 8 GPR argument registers to
  69     // the stack, allowing va_start to index over them in memory if its varargs.
  70     // Because we cannot tell if this is needed on the caller side, we have to
  71     // conservatively assume that it is needed.  As such, make sure we have at
  72     // least enough stack space for the caller to store the 8 GPRs.
  73     if (isMacho)
  74       return 8 * (LP64 ? 8 : 4);
  75
  76     // For ELF 32 ABI:
  77     // There is no default stack allocated for the 8 first GPR arguments.
  78     return 0;
  79   }
  80
  81   /// getMinCallFrameSize - Return the minimum size a call frame can be using
  82   /// the PowerPC ABI.
  83   static unsigned getMinCallFrameSize(bool LP64, bool isMacho) {
  84     // The call frame needs to be at least big enough for linkage and 8 args.
  85     return getLinkageSize(LP64, isMacho) +
  86            getMinCallArgumentsSize(LP64, isMacho);
  87   }
  88
  89 };
  90
  91 } // End llvm namespace
  92
  93 #endif