LLVM  8.0.1
TargetFrameLoweringImpl.cpp
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1 //===- TargetFrameLoweringImpl.cpp - Implement target frame interface ------==//
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 // Implements the layout of a stack frame on the target machine.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ADT/BitVector.h"
21 #include "llvm/IR/Attributes.h"
22 #include "llvm/IR/CallingConv.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/MC/MCRegisterInfo.h"
25 #include "llvm/Support/Compiler.h"
28 
29 using namespace llvm;
30 
32 
37  return false;
38 }
39 
40 /// Returns the displacement from the frame register to the stack
41 /// frame of the specified index, along with the frame register used
42 /// (in output arg FrameReg). This is the default implementation which
43 /// is overridden for some targets.
45  int FI, unsigned &FrameReg) const {
46  const MachineFrameInfo &MFI = MF.getFrameInfo();
48 
49  // By default, assume all frame indices are referenced via whatever
50  // getFrameRegister() says. The target can override this if it's doing
51  // something different.
52  FrameReg = RI->getFrameRegister(MF);
53 
54  return MFI.getObjectOffset(FI) + MFI.getStackSize() -
56 }
57 
59  const MachineFunction &MF) const {
60  return MF.getFrameInfo().hasStackObjects();
61 }
62 
64  BitVector &SavedRegs,
65  RegScavenger *RS) const {
67 
68  // Resize before the early returns. Some backends expect that
69  // SavedRegs.size() == TRI.getNumRegs() after this call even if there are no
70  // saved registers.
71  SavedRegs.resize(TRI.getNumRegs());
72 
73  // When interprocedural register allocation is enabled caller saved registers
74  // are preferred over callee saved registers.
76  return;
77 
78  // Get the callee saved register list...
79  const MCPhysReg *CSRegs = MF.getRegInfo().getCalleeSavedRegs();
80 
81  // Early exit if there are no callee saved registers.
82  if (!CSRegs || CSRegs[0] == 0)
83  return;
84 
85  // In Naked functions we aren't going to save any registers.
87  return;
88 
89  // Noreturn+nounwind functions never restore CSR, so no saves are needed.
90  // Purely noreturn functions may still return through throws, so those must
91  // save CSR for caller exception handlers.
92  //
93  // If the function uses longjmp to break out of its current path of
94  // execution we do not need the CSR spills either: setjmp stores all CSRs
95  // it was called with into the jmp_buf, which longjmp then restores.
100  return;
101 
102  // Functions which call __builtin_unwind_init get all their registers saved.
103  bool CallsUnwindInit = MF.callsUnwindInit();
104  const MachineRegisterInfo &MRI = MF.getRegInfo();
105  for (unsigned i = 0; CSRegs[i]; ++i) {
106  unsigned Reg = CSRegs[i];
107  if (CallsUnwindInit || MRI.isPhysRegModified(Reg))
108  SavedRegs.set(Reg);
109  }
110 }
111 
113  const MachineFunction &MF) const {
114  // When HHVM function is called, the stack is skewed as the return address
115  // is removed from the stack before we enter the function.
117  return MF.getTarget().getAllocaPointerSize();
118 
119  return 0;
120 }
121 
123  llvm_unreachable("getInitialCFAOffset() not implemented!");
124 }
125 
127  const {
128  llvm_unreachable("getInitialCFARegister() not implemented!");
129 }
void resize(unsigned N, bool t=false)
resize - Grow or shrink the bitvector.
Definition: BitVector.h:372
BitVector & set()
Definition: BitVector.h:398
This class represents lattice values for constants.
Definition: AllocatorList.h:24
virtual int getFrameIndexReference(const MachineFunction &MF, int FI, unsigned &FrameReg) const
getFrameIndexReference - This method should return the base register and offset used to reference a f...
virtual const TargetRegisterInfo * getRegisterInfo() const
getRegisterInfo - If register information is available, return it.
bool hasStackObjects() const
Return true if there are any stack objects in this function.
bool isPhysRegModified(unsigned PhysReg, bool SkipNoReturnDef=false) const
Return true if the specified register is modified in this function.
unsigned Reg
bool hasFnAttribute(Attribute::AttrKind Kind) const
Return true if the function has the attribute.
Definition: Function.h:321
unsigned const TargetRegisterInfo * TRI
int getOffsetOfLocalArea() const
getOffsetOfLocalArea - This method returns the offset of the local area from the stack pointer on ent...
virtual void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs, RegScavenger *RS=nullptr) const
This method determines which of the registers reported by TargetRegisterInfo::getCalleeSavedRegs() sh...
#define LLVM_UNLIKELY(EXPR)
Definition: Compiler.h:192
static bool isSafeForNoCSROpt(const Function &F)
Check if given function is safe for not having callee saved registers.
unsigned EnableIPRA
This flag enables InterProcedural Register Allocation (IPRA).
int64_t getObjectOffset(int ObjectIdx) const
Return the assigned stack offset of the specified object from the incoming stack pointer.
This file contains the simple types necessary to represent the attributes associated with functions a...
The MachineFrameInfo class represents an abstract stack frame until prolog/epilog code is inserted...
virtual unsigned getFrameRegister(const MachineFunction &MF) const =0
Debug information queries.
virtual unsigned getStackAlignmentSkew(const MachineFunction &MF) const
Return the skew that has to be applied to stack alignment under certain conditions (e...
virtual bool needsFrameIndexResolution(const MachineFunction &MF) const
uint16_t MCPhysReg
An unsigned integer type large enough to represent all physical registers, but not necessarily virtua...
unsigned getAllocaPointerSize() const
unsigned getNumRegs() const
Return the number of registers this target has (useful for sizing arrays holding per register informa...
unsigned const MachineRegisterInfo * MRI
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
MachineFrameInfo & getFrameInfo()
getFrameInfo - Return the frame info object for the current function.
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
CallingConv::ID getCallingConv() const
getCallingConv()/setCallingConv(CC) - These method get and set the calling convention of this functio...
Definition: Function.h:213
bool callsUnwindInit() const
const Function & getFunction() const
Return the LLVM function that this machine code represents.
MachineRegisterInfo - Keep track of information for virtual and physical registers, including vreg register classes, use/def chains for registers, etc.
MachineRegisterInfo & getRegInfo()
getRegInfo - Return information about the registers currently in use.
virtual bool enableCalleeSaveSkip(const MachineFunction &MF) const
Returns true if the target can safely skip saving callee-saved registers for noreturn nounwind functi...
TargetOptions Options
Definition: TargetMachine.h:97
int getOffsetAdjustment() const
Return the correction for frame offsets.
Calling convention used by HipHop Virtual Machine (HHVM) to perform calls to and from translation cac...
Definition: CallingConv.h:164
const LLVMTargetMachine & getTarget() const
getTarget - Return the target machine this machine code is compiled with
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
const MCPhysReg * getCalleeSavedRegs() const
Returns list of callee saved registers.
uint64_t getStackSize() const
Return the number of bytes that must be allocated to hold all of the fixed size frame objects...
virtual int getInitialCFAOffset(const MachineFunction &MF) const
Return initial CFA offset value i.e.
virtual unsigned getInitialCFARegister(const MachineFunction &MF) const
Return initial CFA register value i.e.