1 //===-- BPFRegisterInfo.cpp - BPF Register Information ----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the BPF implementation of the TargetRegisterInfo class.
12 //===----------------------------------------------------------------------===//
14 #include "BPFRegisterInfo.h"
16 #include "BPFSubtarget.h"
17 #include "llvm/CodeGen/MachineFrameInfo.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstrBuilder.h"
20 #include "llvm/CodeGen/RegisterScavenging.h"
21 #include "llvm/CodeGen/TargetFrameLowering.h"
22 #include "llvm/CodeGen/TargetInstrInfo.h"
23 #include "llvm/IR/DiagnosticInfo.h"
24 #include "llvm/Support/ErrorHandling.h"
26 #define GET_REGINFO_TARGET_DESC
27 #include "BPFGenRegisterInfo.inc"
30 BPFRegisterInfo::BPFRegisterInfo()
31 : BPFGenRegisterInfo(BPF::R0) {}
34 BPFRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
38 BitVector BPFRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
39 BitVector Reserved(getNumRegs());
40 markSuperRegs(Reserved, BPF::W10); // [W|R]10 is read only frame pointer
41 markSuperRegs(Reserved, BPF::W11); // [W|R]11 is pseudo stack pointer
45 static void WarnSize(int Offset, MachineFunction &MF, DebugLoc& DL)
48 const Function &F = MF.getFunction();
49 DiagnosticInfoUnsupported DiagStackSize(F,
50 "Looks like the BPF stack limit of 512 bytes is exceeded. "
51 "Please move large on stack variables into BPF per-cpu array map.\n",
53 F.getContext().diagnose(DiagStackSize);
57 void BPFRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
58 int SPAdj, unsigned FIOperandNum,
59 RegScavenger *RS) const {
60 assert(SPAdj == 0 && "Unexpected");
63 MachineInstr &MI = *II;
64 MachineBasicBlock &MBB = *MI.getParent();
65 MachineFunction &MF = *MBB.getParent();
66 DebugLoc DL = MI.getDebugLoc();
69 /* try harder to get some debug loc */
71 if (I.getDebugLoc()) {
76 while (!MI.getOperand(i).isFI()) {
78 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
81 unsigned FrameReg = getFrameRegister(MF);
82 int FrameIndex = MI.getOperand(i).getIndex();
83 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
85 if (MI.getOpcode() == BPF::MOV_rr) {
86 int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex);
88 WarnSize(Offset, MF, DL);
89 MI.getOperand(i).ChangeToRegister(FrameReg, false);
90 unsigned reg = MI.getOperand(i - 1).getReg();
91 BuildMI(MBB, ++II, DL, TII.get(BPF::ADD_ri), reg)
97 int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex) +
98 MI.getOperand(i + 1).getImm();
100 if (!isInt<32>(Offset))
101 llvm_unreachable("bug in frame offset");
103 WarnSize(Offset, MF, DL);
105 if (MI.getOpcode() == BPF::FI_ri) {
106 // architecture does not really support FI_ri, replace it with
107 // MOV_rr <target_reg>, frame_reg
108 // ADD_ri <target_reg>, imm
109 unsigned reg = MI.getOperand(i - 1).getReg();
111 BuildMI(MBB, ++II, DL, TII.get(BPF::MOV_rr), reg)
113 BuildMI(MBB, II, DL, TII.get(BPF::ADD_ri), reg)
117 // Remove FI_ri instruction
118 MI.eraseFromParent();
120 MI.getOperand(i).ChangeToRegister(FrameReg, false);
121 MI.getOperand(i + 1).ChangeToImmediate(Offset);
125 unsigned BPFRegisterInfo::getFrameRegister(const MachineFunction &MF) const {