1 files changed, 344 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
new file mode 100644
index 000000000000..22f458e4b03e
--- /dev/null
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -0,0 +1,344 @@
+//===-- llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp -------*- C++ -*--===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Common functionality for different debug information format backends.
+// LLVM currently supports DWARF and CodeView.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/DebugHandlerBase.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/MC/MCStreamer.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "dwarfdebug"
+
+Optional<DbgVariableLocation>
+DbgVariableLocation::extractFromMachineInstruction(
+    const MachineInstr &Instruction) {
+  DbgVariableLocation Location;
+  if (!Instruction.isDebugValue())
+    return None;
+  if (!Instruction.getOperand(0).isReg())
+    return None;
+  Location.Register = Instruction.getOperand(0).getReg();
+  Location.FragmentInfo.reset();
+  // We only handle expressions generated by DIExpression::appendOffset,
+  // which doesn't require a full stack machine.
+  int64_t Offset = 0;
+  const DIExpression *DIExpr = Instruction.getDebugExpression();
+  auto Op = DIExpr->expr_op_begin();
+  while (Op != DIExpr->expr_op_end()) {
+    switch (Op->getOp()) {
+    case dwarf::DW_OP_constu: {
+      int Value = Op->getArg(0);
+      ++Op;
+      if (Op != DIExpr->expr_op_end()) {
+        switch (Op->getOp()) {
+        case dwarf::DW_OP_minus:
+          Offset -= Value;
+          break;
+        case dwarf::DW_OP_plus:
+          Offset += Value;
+          break;
+        default:
+          continue;
+        }
+      }
+    } break;
+    case dwarf::DW_OP_plus_uconst:
+      Offset += Op->getArg(0);
+      break;
+    case dwarf::DW_OP_LLVM_fragment:
+      Location.FragmentInfo = {Op->getArg(1), Op->getArg(0)};
+      break;
+    case dwarf::DW_OP_deref:
+      Location.LoadChain.push_back(Offset);
+      Offset = 0;
+      break;
+    default:
+      return None;
+    }
+    ++Op;
+  }
+
+  // Do one final implicit DW_OP_deref if this was an indirect DBG_VALUE
+  // instruction.
+  // FIXME: Replace these with DIExpression.
+  if (Instruction.isIndirectDebugValue())
+    Location.LoadChain.push_back(Offset);
+
+  return Location;
+}
+
+DebugHandlerBase::DebugHandlerBase(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {}
+
+// Each LexicalScope has first instruction and last instruction to mark
+// beginning and end of a scope respectively. Create an inverse map that list
+// scopes starts (and ends) with an instruction. One instruction may start (or
+// end) multiple scopes. Ignore scopes that are not reachable.
+void DebugHandlerBase::identifyScopeMarkers() {
+  SmallVector<LexicalScope *, 4> WorkList;
+  WorkList.push_back(LScopes.getCurrentFunctionScope());
+  while (!WorkList.empty()) {
+    LexicalScope *S = WorkList.pop_back_val();
+
+    const SmallVectorImpl<LexicalScope *> &Children = S->getChildren();
+    if (!Children.empty())
+      WorkList.append(Children.begin(), Children.end());
+
+    if (S->isAbstractScope())
+      continue;
+
+    for (const InsnRange &R : S->getRanges()) {
+      assert(R.first && "InsnRange does not have first instruction!");
+      assert(R.second && "InsnRange does not have second instruction!");
+      requestLabelBeforeInsn(R.first);
+      requestLabelAfterInsn(R.second);
+    }
+  }
+}
+
+// Return Label preceding the instruction.
+MCSymbol *DebugHandlerBase::getLabelBeforeInsn(const MachineInstr *MI) {
+  MCSymbol *Label = LabelsBeforeInsn.lookup(MI);
+  assert(Label && "Didn't insert label before instruction");
+  return Label;
+}
+
+// Return Label immediately following the instruction.
+MCSymbol *DebugHandlerBase::getLabelAfterInsn(const MachineInstr *MI) {
+  return LabelsAfterInsn.lookup(MI);
+}
+
+// Return the function-local offset of an instruction.
+const MCExpr *
+DebugHandlerBase::getFunctionLocalOffsetAfterInsn(const MachineInstr *MI) {
+  MCContext &MC = Asm->OutContext;
+
+  MCSymbol *Start = Asm->getFunctionBegin();
+  const auto *StartRef = MCSymbolRefExpr::create(Start, MC);
+
+  MCSymbol *AfterInsn = getLabelAfterInsn(MI);
+  assert(AfterInsn && "Expected label after instruction");
+  const auto *AfterRef = MCSymbolRefExpr::create(AfterInsn, MC);
+
+  return MCBinaryExpr::createSub(AfterRef, StartRef, MC);
+}
+
+/// If this type is derived from a base type then return base type size.
+uint64_t DebugHandlerBase::getBaseTypeSize(const DIType *Ty) {
+  assert(Ty);
+  const DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty);
+  if (!DDTy)
+    return Ty->getSizeInBits();
+
+  unsigned Tag = DDTy->getTag();
+
+  if (Tag != dwarf::DW_TAG_member && Tag != dwarf::DW_TAG_typedef &&
+      Tag != dwarf::DW_TAG_const_type && Tag != dwarf::DW_TAG_volatile_type &&
+      Tag != dwarf::DW_TAG_restrict_type && Tag != dwarf::DW_TAG_atomic_type)
+    return DDTy->getSizeInBits();
+
+  DIType *BaseType = DDTy->getBaseType();
+
+  if (!BaseType)
+    return 0;
+
+  // If this is a derived type, go ahead and get the base type, unless it's a
+  // reference then it's just the size of the field. Pointer types have no need
+  // of this since they're a different type of qualification on the type.
+  if (BaseType->getTag() == dwarf::DW_TAG_reference_type ||
+      BaseType->getTag() == dwarf::DW_TAG_rvalue_reference_type)
+    return Ty->getSizeInBits();
+
+  return getBaseTypeSize(BaseType);
+}
+
+static bool hasDebugInfo(const MachineModuleInfo *MMI,
+                         const MachineFunction *MF) {
+  if (!MMI->hasDebugInfo())
+    return false;
+  auto *SP = MF->getFunction().getSubprogram();
+  if (!SP)
+    return false;
+  assert(SP->getUnit());
+  auto EK = SP->getUnit()->getEmissionKind();
+  if (EK == DICompileUnit::NoDebug)
+    return false;
+  return true;
+}
+
+void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
+  PrevInstBB = nullptr;
+
+  if (!Asm || !hasDebugInfo(MMI, MF)) {
+    skippedNonDebugFunction();
+    return;
+  }
+
+  // Grab the lexical scopes for the function, if we don't have any of those
+  // then we're not going to be able to do anything.
+  LScopes.initialize(*MF);
+  if (LScopes.empty()) {
+    beginFunctionImpl(MF);
+    return;
+  }
+
+  // Make sure that each lexical scope will have a begin/end label.
+  identifyScopeMarkers();
+
+  // Calculate history for local variables.
+  assert(DbgValues.empty() && "DbgValues map wasn't cleaned!");
+  assert(DbgLabels.empty() && "DbgLabels map wasn't cleaned!");
+  calculateDbgEntityHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(),
+                            DbgValues, DbgLabels);
+  LLVM_DEBUG(DbgValues.dump());
+
+  // Request labels for the full history.
+  for (const auto &I : DbgValues) {
+    const auto &Entries = I.second;
+    if (Entries.empty())
+      continue;
+
+    auto IsDescribedByReg = [](const MachineInstr *MI) {
+      return MI->getOperand(0).isReg() && MI->getOperand(0).getReg();
+    };
+
+    // The first mention of a function argument gets the CurrentFnBegin label,
+    // so arguments are visible when breaking at function entry.
+    //
+    // We do not change the label for values that are described by registers,
+    // as that could place them above their defining instructions. We should
+    // ideally not change the labels for constant debug values either, since
+    // doing that violates the ranges that are calculated in the history map.
+    // However, we currently do not emit debug values for constant arguments
+    // directly at the start of the function, so this code is still useful.
+    const DILocalVariable *DIVar =
+        Entries.front().getInstr()->getDebugVariable();
+    if (DIVar->isParameter() &&
+        getDISubprogram(DIVar->getScope())->describes(&MF->getFunction())) {
+      if (!IsDescribedByReg(Entries.front().getInstr()))
+        LabelsBeforeInsn[Entries.front().getInstr()] = Asm->getFunctionBegin();
+      if (Entries.front().getInstr()->getDebugExpression()->isFragment()) {
+        // Mark all non-overlapping initial fragments.
+        for (auto I = Entries.begin(); I != Entries.end(); ++I) {
+          if (!I->isDbgValue())
+            continue;
+          const DIExpression *Fragment = I->getInstr()->getDebugExpression();
+          if (std::any_of(Entries.begin(), I,
+                          [&](DbgValueHistoryMap::Entry Pred) {
+                            return Pred.isDbgValue() &&
+                                   Fragment->fragmentsOverlap(
+                                       Pred.getInstr()->getDebugExpression());
+                          }))
+            break;
+          // The code that generates location lists for DWARF assumes that the
+          // entries' start labels are monotonically increasing, and since we
+          // don't change the label for fragments that are described by
+          // registers, we must bail out when encountering such a fragment.
+          if (IsDescribedByReg(I->getInstr()))
+            break;
+          LabelsBeforeInsn[I->getInstr()] = Asm->getFunctionBegin();
+        }
+      }
+    }
+
+    for (const auto &Entry : Entries) {
+      if (Entry.isDbgValue())
+        requestLabelBeforeInsn(Entry.getInstr());
+      else
+        requestLabelAfterInsn(Entry.getInstr());
+    }
+  }
+
+  // Ensure there is a symbol before DBG_LABEL.
+  for (const auto &I : DbgLabels) {
+    const MachineInstr *MI = I.second;
+    requestLabelBeforeInsn(MI);
+  }
+
+  PrevInstLoc = DebugLoc();
+  PrevLabel = Asm->getFunctionBegin();
+  beginFunctionImpl(MF);
+}
+
+void DebugHandlerBase::beginInstruction(const MachineInstr *MI) {
+  if (!MMI->hasDebugInfo())
+    return;
+
+  assert(CurMI == nullptr);
+  CurMI = MI;
+
+  // Insert labels where requested.
+  DenseMap<const MachineInstr *, MCSymbol *>::iterator I =
+      LabelsBeforeInsn.find(MI);
+
+  // No label needed.
+  if (I == LabelsBeforeInsn.end())
+    return;
+
+  // Label already assigned.
+  if (I->second)
+    return;
+
+  if (!PrevLabel) {
+    PrevLabel = MMI->getContext().createTempSymbol();
+    Asm->OutStreamer->EmitLabel(PrevLabel);
+  }
+  I->second = PrevLabel;
+}
+
+void DebugHandlerBase::endInstruction() {
+  if (!MMI->hasDebugInfo())
+    return;
+
+  assert(CurMI != nullptr);
+  // Don't create a new label after DBG_VALUE and other instructions that don't
+  // generate code.
+  if (!CurMI->isMetaInstruction()) {
+    PrevLabel = nullptr;
+    PrevInstBB = CurMI->getParent();
+  }
+
+  DenseMap<const MachineInstr *, MCSymbol *>::iterator I =
+      LabelsAfterInsn.find(CurMI);
+  CurMI = nullptr;
+
+  // No label needed.
+  if (I == LabelsAfterInsn.end())
+    return;
+
+  // Label already assigned.
+  if (I->second)
+    return;
+
+  // We need a label after this instruction.
+  if (!PrevLabel) {
+    PrevLabel = MMI->getContext().createTempSymbol();
+    Asm->OutStreamer->EmitLabel(PrevLabel);
+  }
+  I->second = PrevLabel;
+}
+
+void DebugHandlerBase::endFunction(const MachineFunction *MF) {
+  if (hasDebugInfo(MMI, MF))
+    endFunctionImpl(MF);
+  DbgValues.clear();
+  DbgLabels.clear();
+  LabelsBeforeInsn.clear();
+  LabelsAfterInsn.clear();
+}