1 files changed, 232 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/ARMMCInstLower.cpp b/llvm/lib/Target/ARM/ARMMCInstLower.cpp
new file mode 100644
index 000000000000..c92689f4942e
--- /dev/null
+++ b/llvm/lib/Target/ARM/ARMMCInstLower.cpp
@@ -0,0 +1,232 @@
+//===-- ARMMCInstLower.cpp - Convert ARM MachineInstr to an MCInst --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains code to lower ARM MachineInstrs to their corresponding
+// MCInst records.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARM.h"
+#include "ARMAsmPrinter.h"
+#include "ARMBaseInstrInfo.h"
+#include "ARMMachineFunctionInfo.h"
+#include "ARMSubtarget.h"
+#include "MCTargetDesc/ARMAddressingModes.h"
+#include "MCTargetDesc/ARMBaseInfo.h"
+#include "MCTargetDesc/ARMMCExpr.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstBuilder.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <cassert>
+#include <cstdint>
+
+using namespace llvm;
+
+MCOperand ARMAsmPrinter::GetSymbolRef(const MachineOperand &MO,
+                                      const MCSymbol *Symbol) {
+  MCSymbolRefExpr::VariantKind SymbolVariant = MCSymbolRefExpr::VK_None;
+  if (MO.getTargetFlags() & ARMII::MO_SBREL)
+    SymbolVariant = MCSymbolRefExpr::VK_ARM_SBREL;
+
+  const MCExpr *Expr =
+      MCSymbolRefExpr::create(Symbol, SymbolVariant, OutContext);
+  switch (MO.getTargetFlags() & ARMII::MO_OPTION_MASK) {
+  default:
+    llvm_unreachable("Unknown target flag on symbol operand");
+  case ARMII::MO_NO_FLAG:
+    break;
+  case ARMII::MO_LO16:
+    Expr =
+        MCSymbolRefExpr::create(Symbol, SymbolVariant, OutContext);
+    Expr = ARMMCExpr::createLower16(Expr, OutContext);
+    break;
+  case ARMII::MO_HI16:
+    Expr =
+        MCSymbolRefExpr::create(Symbol, SymbolVariant, OutContext);
+    Expr = ARMMCExpr::createUpper16(Expr, OutContext);
+    break;
+  }
+
+  if (!MO.isJTI() && MO.getOffset())
+    Expr = MCBinaryExpr::createAdd(Expr,
+                                   MCConstantExpr::create(MO.getOffset(),
+                                                          OutContext),
+                                   OutContext);
+  return MCOperand::createExpr(Expr);
+
+}
+
+bool ARMAsmPrinter::lowerOperand(const MachineOperand &MO,
+                                 MCOperand &MCOp) {
+  switch (MO.getType()) {
+  default: llvm_unreachable("unknown operand type");
+  case MachineOperand::MO_Register:
+    // Ignore all implicit register operands.
+    if (MO.isImplicit())
+      return false;
+    assert(!MO.getSubReg() && "Subregs should be eliminated!");
+    MCOp = MCOperand::createReg(MO.getReg());
+    break;
+  case MachineOperand::MO_Immediate:
+    MCOp = MCOperand::createImm(MO.getImm());
+    break;
+  case MachineOperand::MO_MachineBasicBlock:
+    MCOp = MCOperand::createExpr(MCSymbolRefExpr::create(
+        MO.getMBB()->getSymbol(), OutContext));
+    break;
+  case MachineOperand::MO_GlobalAddress:
+    MCOp = GetSymbolRef(MO,
+                        GetARMGVSymbol(MO.getGlobal(), MO.getTargetFlags()));
+    break;
+  case MachineOperand::MO_ExternalSymbol:
+    MCOp = GetSymbolRef(MO,
+                        GetExternalSymbolSymbol(MO.getSymbolName()));
+    break;
+  case MachineOperand::MO_JumpTableIndex:
+    MCOp = GetSymbolRef(MO, GetJTISymbol(MO.getIndex()));
+    break;
+  case MachineOperand::MO_ConstantPoolIndex:
+    if (Subtarget->genExecuteOnly())
+      llvm_unreachable("execute-only should not generate constant pools");
+    MCOp = GetSymbolRef(MO, GetCPISymbol(MO.getIndex()));
+    break;
+  case MachineOperand::MO_BlockAddress:
+    MCOp = GetSymbolRef(MO, GetBlockAddressSymbol(MO.getBlockAddress()));
+    break;
+  case MachineOperand::MO_FPImmediate: {
+    APFloat Val = MO.getFPImm()->getValueAPF();
+    bool ignored;
+    Val.convert(APFloat::IEEEdouble(), APFloat::rmTowardZero, &ignored);
+    MCOp = MCOperand::createFPImm(Val.convertToDouble());
+    break;
+  }
+  case MachineOperand::MO_RegisterMask:
+    // Ignore call clobbers.
+    return false;
+  }
+  return true;
+}
+
+void llvm::LowerARMMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
+                                        ARMAsmPrinter &AP) {
+  OutMI.setOpcode(MI->getOpcode());
+
+  // In the MC layer, we keep modified immediates in their encoded form
+  bool EncodeImms = false;
+  switch (MI->getOpcode()) {
+  default: break;
+  case ARM::MOVi:
+  case ARM::MVNi:
+  case ARM::CMPri:
+  case ARM::CMNri:
+  case ARM::TSTri:
+  case ARM::TEQri:
+  case ARM::MSRi:
+  case ARM::ADCri:
+  case ARM::ADDri:
+  case ARM::ADDSri:
+  case ARM::SBCri:
+  case ARM::SUBri:
+  case ARM::SUBSri:
+  case ARM::ANDri:
+  case ARM::ORRri:
+  case ARM::EORri:
+  case ARM::BICri:
+  case ARM::RSBri:
+  case ARM::RSBSri:
+  case ARM::RSCri:
+    EncodeImms = true;
+    break;
+  }
+
+  for (const MachineOperand &MO : MI->operands()) {
+    MCOperand MCOp;
+    if (AP.lowerOperand(MO, MCOp)) {
+      if (MCOp.isImm() && EncodeImms) {
+        int32_t Enc = ARM_AM::getSOImmVal(MCOp.getImm());
+        if (Enc != -1)
+          MCOp.setImm(Enc);
+      }
+      OutMI.addOperand(MCOp);
+    }
+  }
+}
+
+void ARMAsmPrinter::EmitSled(const MachineInstr &MI, SledKind Kind)
+{
+  if (MI.getParent()->getParent()->getInfo<ARMFunctionInfo>()
+    ->isThumbFunction())
+  {
+    MI.emitError("An attempt to perform XRay instrumentation for a"
+      " Thumb function (not supported). Detected when emitting a sled.");
+    return;
+  }
+  static const int8_t NoopsInSledCount = 6;
+  // We want to emit the following pattern:
+  //
+  // .Lxray_sled_N:
+  //   ALIGN
+  //   B #20
+  //   ; 6 NOP instructions (24 bytes)
+  // .tmpN
+  //
+  // We need the 24 bytes (6 instructions) because at runtime, we'd be patching
+  // over the full 28 bytes (7 instructions) with the following pattern:
+  //
+  //   PUSH{ r0, lr }
+  //   MOVW r0, #<lower 16 bits of function ID>
+  //   MOVT r0, #<higher 16 bits of function ID>
+  //   MOVW ip, #<lower 16 bits of address of __xray_FunctionEntry/Exit>
+  //   MOVT ip, #<higher 16 bits of address of __xray_FunctionEntry/Exit>
+  //   BLX ip
+  //   POP{ r0, lr }
+  //
+  OutStreamer->EmitCodeAlignment(4);
+  auto CurSled = OutContext.createTempSymbol("xray_sled_", true);
+  OutStreamer->EmitLabel(CurSled);
+  auto Target = OutContext.createTempSymbol();
+
+  // Emit "B #20" instruction, which jumps over the next 24 bytes (because
+  // register pc is 8 bytes ahead of the jump instruction by the moment CPU
+  // is executing it).
+  // By analogy to ARMAsmPrinter::emitPseudoExpansionLowering() |case ARM::B|.
+  // It is not clear why |addReg(0)| is needed (the last operand).
+  EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::Bcc).addImm(20)
+    .addImm(ARMCC::AL).addReg(0));
+
+  MCInst Noop;
+  Subtarget->getInstrInfo()->getNoop(Noop);
+  for (int8_t I = 0; I < NoopsInSledCount; I++)
+    OutStreamer->EmitInstruction(Noop, getSubtargetInfo());
+
+  OutStreamer->EmitLabel(Target);
+  recordSled(CurSled, MI, Kind);
+}
+
+void ARMAsmPrinter::LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI)
+{
+  EmitSled(MI, SledKind::FUNCTION_ENTER);
+}
+
+void ARMAsmPrinter::LowerPATCHABLE_FUNCTION_EXIT(const MachineInstr &MI)
+{
+  EmitSled(MI, SledKind::FUNCTION_EXIT);
+}
+
+void ARMAsmPrinter::LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI)
+{
+  EmitSled(MI, SledKind::TAIL_CALL);
+}