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llvm-6502/lib/Target/Mips/MipsAsmPrinter.cpp
Bruno Cardoso Lopes 47b92f3d83 Mips MC object code emission improvements: 
"With this patch we can now generate runnable Mips code through LLVM
direct object emission. We have run numerous simple programs, both C
and C++ and with -O0 and -O3 from the output. The code is not production
ready, but quite useful for experimentation." Patch and message by
Jack Carter

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144414 91177308-0d34-0410-b5e6-96231b3b80d8
2011-11-11 22:58:42 +00:00

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//===-- MipsAsmPrinter.cpp - Mips LLVM assembly writer --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a printer that converts from our internal representation
// of machine-dependent LLVM code to GAS-format MIPS assembly language.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mips-asm-printer"
#include "Mips.h"
#include "MipsAsmPrinter.h"
#include "MipsInstrInfo.h"
#include "MipsMachineFunction.h"
#include "MipsMCInstLower.h"
#include "MipsMCSymbolRefExpr.h"
#include "InstPrinter/MipsInstPrinter.h"
#include "MCTargetDesc/MipsBaseInfo.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/Instructions.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
static bool isUnalignedLoadStore(unsigned Opc) {
return Opc == Mips::ULW || Opc == Mips::ULH || Opc == Mips::ULHu ||
Opc == Mips::USW || Opc == Mips::USH ||
Opc == Mips::ULW_P8 || Opc == Mips::ULH_P8 || Opc == Mips::ULHu_P8 ||
Opc == Mips::USW_P8 || Opc == Mips::USH_P8;
}
static bool isDirective(unsigned Opc) {
return Opc == Mips::MACRO || Opc == Mips::NOMACRO ||
Opc == Mips::REORDER || Opc == Mips::NOREORDER ||
Opc == Mips::ATMACRO || Opc == Mips::NOAT;
}
void MipsAsmPrinter::EmitInstruction(const MachineInstr *MI) {
SmallString<128> Str;
raw_svector_ostream OS(Str);
if (MI->isDebugValue()) {
PrintDebugValueComment(MI, OS);
return;
}
MipsMCInstLower MCInstLowering(Mang, *MF, *this);
unsigned Opc = MI->getOpcode();
MCInst TmpInst0;
SmallVector<MCInst, 4> MCInsts;
MCInstLowering.Lower(MI, TmpInst0);
if (!OutStreamer.hasRawTextSupport() && isDirective(Opc))
return;
// Enclose unaligned load or store with .macro & .nomacro directives.
if (isUnalignedLoadStore(Opc)) {
MCInst Directive;
Directive.setOpcode(Mips::MACRO);
OutStreamer.EmitInstruction(Directive);
OutStreamer.EmitInstruction(TmpInst0);
Directive.setOpcode(Mips::NOMACRO);
OutStreamer.EmitInstruction(Directive);
return;
}
if (!OutStreamer.hasRawTextSupport()) {
// Lower CPLOAD and CPRESTORE
if (Opc == Mips::CPLOAD) {
MCInstLowering.LowerCPLOAD(MI, MCInsts);
for (SmallVector<MCInst, 4>::iterator I = MCInsts.begin();
I != MCInsts.end(); ++I)
OutStreamer.EmitInstruction(*I);
return;
}
if (Opc == Mips::CPRESTORE) {
MCInstLowering.LowerCPRESTORE(MI, TmpInst0);
OutStreamer.EmitInstruction(TmpInst0);
return;
}
}
OutStreamer.EmitInstruction(TmpInst0);
}
//===----------------------------------------------------------------------===//
//
// Mips Asm Directives
//
// -- Frame directive "frame Stackpointer, Stacksize, RARegister"
// Describe the stack frame.
//
// -- Mask directives "(f)mask bitmask, offset"
// Tells the assembler which registers are saved and where.
// bitmask - contain a little endian bitset indicating which registers are
// saved on function prologue (e.g. with a 0x80000000 mask, the
// assembler knows the register 31 (RA) is saved at prologue.
// offset - the position before stack pointer subtraction indicating where
// the first saved register on prologue is located. (e.g. with a
//
// Consider the following function prologue:
//
// .frame $fp,48,$ra
// .mask 0xc0000000,-8
// addiu $sp, $sp, -48
// sw $ra, 40($sp)
// sw $fp, 36($sp)
//
// With a 0xc0000000 mask, the assembler knows the register 31 (RA) and
// 30 (FP) are saved at prologue. As the save order on prologue is from
// left to right, RA is saved first. A -8 offset means that after the
// stack pointer subtration, the first register in the mask (RA) will be
// saved at address 48-8=40.
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// Mask directives
//===----------------------------------------------------------------------===//
// Create a bitmask with all callee saved registers for CPU or Floating Point
// registers. For CPU registers consider RA, GP and FP for saving if necessary.
void MipsAsmPrinter::printSavedRegsBitmask(raw_ostream &O) {
// CPU and FPU Saved Registers Bitmasks
unsigned CPUBitmask = 0, FPUBitmask = 0;
int CPUTopSavedRegOff, FPUTopSavedRegOff;
// Set the CPU and FPU Bitmasks
const MachineFrameInfo *MFI = MF->getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
// size of stack area to which FP callee-saved regs are saved.
unsigned CPURegSize = Mips::CPURegsRegisterClass->getSize();
unsigned FGR32RegSize = Mips::FGR32RegisterClass->getSize();
unsigned AFGR64RegSize = Mips::AFGR64RegisterClass->getSize();
bool HasAFGR64Reg = false;
unsigned CSFPRegsSize = 0;
unsigned i, e = CSI.size();
// Set FPU Bitmask.
for (i = 0; i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (Mips::CPURegsRegisterClass->contains(Reg))
break;
unsigned RegNum = MipsRegisterInfo::getRegisterNumbering(Reg);
if (Mips::AFGR64RegisterClass->contains(Reg)) {
FPUBitmask |= (3 << RegNum);
CSFPRegsSize += AFGR64RegSize;
HasAFGR64Reg = true;
continue;
}
FPUBitmask |= (1 << RegNum);
CSFPRegsSize += FGR32RegSize;
}
// Set CPU Bitmask.
for (; i != e; ++i) {
unsigned Reg = CSI[i].getReg();
unsigned RegNum = MipsRegisterInfo::getRegisterNumbering(Reg);
CPUBitmask |= (1 << RegNum);
}
// FP Regs are saved right below where the virtual frame pointer points to.
FPUTopSavedRegOff = FPUBitmask ?
(HasAFGR64Reg ? -AFGR64RegSize : -FGR32RegSize) : 0;
// CPU Regs are saved below FP Regs.
CPUTopSavedRegOff = CPUBitmask ? -CSFPRegsSize - CPURegSize : 0;
// Print CPUBitmask
O << "\t.mask \t"; printHex32(CPUBitmask, O);
O << ',' << CPUTopSavedRegOff << '\n';
// Print FPUBitmask
O << "\t.fmask\t"; printHex32(FPUBitmask, O);
O << "," << FPUTopSavedRegOff << '\n';
}
// Print a 32 bit hex number with all numbers.
void MipsAsmPrinter::printHex32(unsigned Value, raw_ostream &O) {
O << "0x";
for (int i = 7; i >= 0; i--)
O.write_hex((Value & (0xF << (i*4))) >> (i*4));
}
//===----------------------------------------------------------------------===//
// Frame and Set directives
//===----------------------------------------------------------------------===//
/// Frame Directive
void MipsAsmPrinter::emitFrameDirective() {
const TargetRegisterInfo &RI = *TM.getRegisterInfo();
unsigned stackReg = RI.getFrameRegister(*MF);
unsigned returnReg = RI.getRARegister();
unsigned stackSize = MF->getFrameInfo()->getStackSize();
if (OutStreamer.hasRawTextSupport())
OutStreamer.EmitRawText("\t.frame\t$" +
StringRef(MipsInstPrinter::getRegisterName(stackReg)).lower() +
"," + Twine(stackSize) + ",$" +
StringRef(MipsInstPrinter::getRegisterName(returnReg)).lower());
}
/// Emit Set directives.
const char *MipsAsmPrinter::getCurrentABIString() const {
switch (Subtarget->getTargetABI()) {
case MipsSubtarget::O32: return "abi32";
case MipsSubtarget::N32: return "abiN32";
case MipsSubtarget::N64: return "abi64";
case MipsSubtarget::EABI: return "eabi32"; // TODO: handle eabi64
default: break;
}
llvm_unreachable("Unknown Mips ABI");
return NULL;
}
void MipsAsmPrinter::EmitFunctionEntryLabel() {
if (OutStreamer.hasRawTextSupport())
OutStreamer.EmitRawText("\t.ent\t" + Twine(CurrentFnSym->getName()));
OutStreamer.EmitLabel(CurrentFnSym);
}
/// EmitFunctionBodyStart - Targets can override this to emit stuff before
/// the first basic block in the function.
void MipsAsmPrinter::EmitFunctionBodyStart() {
emitFrameDirective();
if (OutStreamer.hasRawTextSupport()) {
SmallString<128> Str;
raw_svector_ostream OS(Str);
printSavedRegsBitmask(OS);
OutStreamer.EmitRawText(OS.str());
}
}
/// EmitFunctionBodyEnd - Targets can override this to emit stuff after
/// the last basic block in the function.
void MipsAsmPrinter::EmitFunctionBodyEnd() {
// There are instruction for this macros, but they must
// always be at the function end, and we can't emit and
// break with BB logic.
if (OutStreamer.hasRawTextSupport()) {
OutStreamer.EmitRawText(StringRef("\t.set\tmacro"));
OutStreamer.EmitRawText(StringRef("\t.set\treorder"));
OutStreamer.EmitRawText("\t.end\t" + Twine(CurrentFnSym->getName()));
}
}
/// isBlockOnlyReachableByFallthough - Return true if the basic block has
/// exactly one predecessor and the control transfer mechanism between
/// the predecessor and this block is a fall-through.
bool MipsAsmPrinter::isBlockOnlyReachableByFallthrough(const MachineBasicBlock*
MBB) const {
// The predecessor has to be immediately before this block.
const MachineBasicBlock *Pred = *MBB->pred_begin();
// If the predecessor is a switch statement, assume a jump table
// implementation, so it is not a fall through.
if (const BasicBlock *bb = Pred->getBasicBlock())
if (isa<SwitchInst>(bb->getTerminator()))
return false;
// If this is a landing pad, it isn't a fall through. If it has no preds,
// then nothing falls through to it.
if (MBB->isLandingPad() || MBB->pred_empty())
return false;
// If there isn't exactly one predecessor, it can't be a fall through.
MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), PI2 = PI;
++PI2;
if (PI2 != MBB->pred_end())
return false;
// The predecessor has to be immediately before this block.
if (!Pred->isLayoutSuccessor(MBB))
return false;
// If the block is completely empty, then it definitely does fall through.
if (Pred->empty())
return true;
// Otherwise, check the last instruction.
// Check if the last terminator is an unconditional branch.
MachineBasicBlock::const_iterator I = Pred->end();
while (I != Pred->begin() && !(--I)->getDesc().isTerminator()) ;
return !I->getDesc().isBarrier();
}
// Print out an operand for an inline asm expression.
bool MipsAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
unsigned AsmVariant,const char *ExtraCode,
raw_ostream &O) {
// Does this asm operand have a single letter operand modifier?
if (ExtraCode && ExtraCode[0])
return true; // Unknown modifier.
printOperand(MI, OpNo, O);
return false;
}
bool MipsAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
unsigned OpNum, unsigned AsmVariant,
const char *ExtraCode,
raw_ostream &O) {
if (ExtraCode && ExtraCode[0])
return true; // Unknown modifier.
const MachineOperand &MO = MI->getOperand(OpNum);
assert(MO.isReg() && "unexpected inline asm memory operand");
O << "0($" << MipsInstPrinter::getRegisterName(MO.getReg()) << ")";
return false;
}
void MipsAsmPrinter::printOperand(const MachineInstr *MI, int opNum,
raw_ostream &O) {
const MachineOperand &MO = MI->getOperand(opNum);
bool closeP = false;
if (MO.getTargetFlags())
closeP = true;
switch(MO.getTargetFlags()) {
case MipsII::MO_GPREL: O << "%gp_rel("; break;
case MipsII::MO_GOT_CALL: O << "%call16("; break;
case MipsII::MO_GOT: O << "%got("; break;
case MipsII::MO_ABS_HI: O << "%hi("; break;
case MipsII::MO_ABS_LO: O << "%lo("; break;
case MipsII::MO_TLSGD: O << "%tlsgd("; break;
case MipsII::MO_GOTTPREL: O << "%gottprel("; break;
case MipsII::MO_TPREL_HI: O << "%tprel_hi("; break;
case MipsII::MO_TPREL_LO: O << "%tprel_lo("; break;
case MipsII::MO_GPOFF_HI: O << "%hi(%neg(%gp_rel("; break;
case MipsII::MO_GPOFF_LO: O << "%lo(%neg(%gp_rel("; break;
case MipsII::MO_GOT_DISP: O << "%got_disp("; break;
case MipsII::MO_GOT_PAGE: O << "%got_page("; break;
case MipsII::MO_GOT_OFST: O << "%got_ofst("; break;
}
switch (MO.getType()) {
case MachineOperand::MO_Register:
O << '$'
<< StringRef(MipsInstPrinter::getRegisterName(MO.getReg())).lower();
break;
case MachineOperand::MO_Immediate:
O << MO.getImm();
break;
case MachineOperand::MO_MachineBasicBlock:
O << *MO.getMBB()->getSymbol();
return;
case MachineOperand::MO_GlobalAddress:
O << *Mang->getSymbol(MO.getGlobal());
break;
case MachineOperand::MO_BlockAddress: {
MCSymbol* BA = GetBlockAddressSymbol(MO.getBlockAddress());
O << BA->getName();
break;
}
case MachineOperand::MO_ExternalSymbol:
O << *GetExternalSymbolSymbol(MO.getSymbolName());
break;
case MachineOperand::MO_JumpTableIndex:
O << MAI->getPrivateGlobalPrefix() << "JTI" << getFunctionNumber()
<< '_' << MO.getIndex();
break;
case MachineOperand::MO_ConstantPoolIndex:
O << MAI->getPrivateGlobalPrefix() << "CPI"
<< getFunctionNumber() << "_" << MO.getIndex();
if (MO.getOffset())
O << "+" << MO.getOffset();
break;
default:
llvm_unreachable("<unknown operand type>");
}
if (closeP) O << ")";
}
void MipsAsmPrinter::printUnsignedImm(const MachineInstr *MI, int opNum,
raw_ostream &O) {
const MachineOperand &MO = MI->getOperand(opNum);
if (MO.isImm())
O << (unsigned short int)MO.getImm();
else
printOperand(MI, opNum, O);
}
void MipsAsmPrinter::
printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O) {
// Load/Store memory operands -- imm($reg)
// If PIC target the target is loaded as the
// pattern lw $25,%call16($28)
printOperand(MI, opNum+1, O);
O << "(";
printOperand(MI, opNum, O);
O << ")";
}
void MipsAsmPrinter::
printMemOperandEA(const MachineInstr *MI, int opNum, raw_ostream &O) {
// when using stack locations for not load/store instructions
// print the same way as all normal 3 operand instructions.
printOperand(MI, opNum, O);
O << ", ";
printOperand(MI, opNum+1, O);
return;
}
void MipsAsmPrinter::
printFCCOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
const char *Modifier) {
const MachineOperand& MO = MI->getOperand(opNum);
O << Mips::MipsFCCToString((Mips::CondCode)MO.getImm());
}
void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
// FIXME: Use SwitchSection.
// Tell the assembler which ABI we are using
if (OutStreamer.hasRawTextSupport())
OutStreamer.EmitRawText("\t.section .mdebug." + Twine(getCurrentABIString()));
// TODO: handle O64 ABI
if (OutStreamer.hasRawTextSupport()) {
if (Subtarget->isABI_EABI()) {
if (Subtarget->isGP32bit())
OutStreamer.EmitRawText(StringRef("\t.section .gcc_compiled_long32"));
else
OutStreamer.EmitRawText(StringRef("\t.section .gcc_compiled_long64"));
}
}
// return to previous section
if (OutStreamer.hasRawTextSupport())
OutStreamer.EmitRawText(StringRef("\t.previous"));
}
MachineLocation
MipsAsmPrinter::getDebugValueLocation(const MachineInstr *MI) const {
// Handles frame addresses emitted in MipsInstrInfo::emitFrameIndexDebugValue.
assert(MI->getNumOperands() == 4 && "Invalid no. of machine operands!");
assert(MI->getOperand(0).isReg() && MI->getOperand(1).isImm() &&
"Unexpected MachineOperand types");
return MachineLocation(MI->getOperand(0).getReg(),
MI->getOperand(1).getImm());
}
void MipsAsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
raw_ostream &OS) {
// TODO: implement
}
// Force static initialization.
extern "C" void LLVMInitializeMipsAsmPrinter() {
RegisterAsmPrinter<MipsAsmPrinter> X(TheMipsTarget);
RegisterAsmPrinter<MipsAsmPrinter> Y(TheMipselTarget);
RegisterAsmPrinter<MipsAsmPrinter> A(TheMips64Target);
RegisterAsmPrinter<MipsAsmPrinter> B(TheMips64elTarget);
}
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