blob: 679ade185e1c69cfbd700282507133af37f91b7e (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
//===----- TargetFrameLoweringImpl.cpp - Implement target frame interface --==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Implements the layout of a stack frame on the target machine.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/BitVector.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/Function.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <cstdlib>
using namespace llvm;
TargetFrameLowering::~TargetFrameLowering() {
}
/// The default implementation just looks at attribute "no-frame-pointer-elim".
bool TargetFrameLowering::noFramePointerElim(const MachineFunction &MF) const {
auto Attr = MF.getFunction()->getFnAttribute("no-frame-pointer-elim");
return Attr.getValueAsString() == "true";
}
/// Returns the displacement from the frame register to the stack
/// frame of the specified index, along with the frame register used
/// (in output arg FrameReg). This is the default implementation which
/// is overridden for some targets.
int TargetFrameLowering::getFrameIndexReference(const MachineFunction &MF,
int FI, unsigned &FrameReg) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo();
// By default, assume all frame indices are referenced via whatever
// getFrameRegister() says. The target can override this if it's doing
// something different.
FrameReg = RI->getFrameRegister(MF);
return MFI->getObjectOffset(FI) + MFI->getStackSize() -
getOffsetOfLocalArea() + MFI->getOffsetAdjustment();
}
bool TargetFrameLowering::needsFrameIndexResolution(
const MachineFunction &MF) const {
return MF.getFrameInfo()->hasStackObjects();
}
void TargetFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
// Get the callee saved register list...
const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo();
const MCPhysReg *CSRegs = TRI.getCalleeSavedRegs(&MF);
// Early exit if there are no callee saved registers.
if (!CSRegs || CSRegs[0] == 0)
return;
SavedRegs.resize(TRI.getNumRegs());
// In Naked functions we aren't going to save any registers.
if (MF.getFunction()->hasFnAttribute(Attribute::Naked))
return;
// Functions which call __builtin_unwind_init get all their registers saved.
bool CallsUnwindInit = MF.getMMI().callsUnwindInit();
const MachineRegisterInfo &MRI = MF.getRegInfo();
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
if (CallsUnwindInit || MRI.isPhysRegModified(Reg))
SavedRegs.set(Reg);
}
}
unsigned TargetFrameLowering::getStackAlignmentSkew(
const MachineFunction &MF) const {
// When HHVM function is called, the stack is skewed as the return address
// is removed from the stack before we enter the function.
if (LLVM_UNLIKELY(MF.getFunction()->getCallingConv() == CallingConv::HHVM))
return MF.getTarget().getPointerSize();
return 0;
}
|
