412 lines
14 KiB
C++
412 lines
14 KiB
C++
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//===-- llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp -------*- C++ -*--===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Common functionality for different debug information format backends.
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// LLVM currently supports DWARF and CodeView.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/DebugHandlerBase.h"
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#include "llvm/ADT/Optional.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/TargetSubtargetInfo.h"
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#include "llvm/IR/DebugInfo.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/Support/CommandLine.h"
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using namespace llvm;
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#define DEBUG_TYPE "dwarfdebug"
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/// If true, we drop variable location ranges which exist entirely outside the
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/// variable's lexical scope instruction ranges.
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static cl::opt<bool> TrimVarLocs("trim-var-locs", cl::Hidden, cl::init(true));
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Optional<DbgVariableLocation>
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DbgVariableLocation::extractFromMachineInstruction(
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const MachineInstr &Instruction) {
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DbgVariableLocation Location;
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if (!Instruction.isDebugValue())
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return None;
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if (!Instruction.getDebugOperand(0).isReg())
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return None;
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Location.Register = Instruction.getDebugOperand(0).getReg();
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Location.FragmentInfo.reset();
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// We only handle expressions generated by DIExpression::appendOffset,
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// which doesn't require a full stack machine.
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int64_t Offset = 0;
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const DIExpression *DIExpr = Instruction.getDebugExpression();
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auto Op = DIExpr->expr_op_begin();
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while (Op != DIExpr->expr_op_end()) {
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switch (Op->getOp()) {
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case dwarf::DW_OP_constu: {
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int Value = Op->getArg(0);
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++Op;
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if (Op != DIExpr->expr_op_end()) {
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switch (Op->getOp()) {
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case dwarf::DW_OP_minus:
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Offset -= Value;
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break;
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case dwarf::DW_OP_plus:
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Offset += Value;
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break;
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default:
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continue;
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}
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}
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} break;
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case dwarf::DW_OP_plus_uconst:
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Offset += Op->getArg(0);
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break;
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case dwarf::DW_OP_LLVM_fragment:
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Location.FragmentInfo = {Op->getArg(1), Op->getArg(0)};
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break;
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case dwarf::DW_OP_deref:
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Location.LoadChain.push_back(Offset);
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Offset = 0;
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break;
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default:
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return None;
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}
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++Op;
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}
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// Do one final implicit DW_OP_deref if this was an indirect DBG_VALUE
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// instruction.
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// FIXME: Replace these with DIExpression.
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if (Instruction.isIndirectDebugValue())
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Location.LoadChain.push_back(Offset);
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return Location;
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}
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DebugHandlerBase::DebugHandlerBase(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {}
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void DebugHandlerBase::beginModule(Module *M) {
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if (M->debug_compile_units().empty())
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Asm = nullptr;
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}
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// Each LexicalScope has first instruction and last instruction to mark
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// beginning and end of a scope respectively. Create an inverse map that list
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// scopes starts (and ends) with an instruction. One instruction may start (or
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// end) multiple scopes. Ignore scopes that are not reachable.
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void DebugHandlerBase::identifyScopeMarkers() {
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SmallVector<LexicalScope *, 4> WorkList;
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WorkList.push_back(LScopes.getCurrentFunctionScope());
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while (!WorkList.empty()) {
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LexicalScope *S = WorkList.pop_back_val();
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const SmallVectorImpl<LexicalScope *> &Children = S->getChildren();
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if (!Children.empty())
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WorkList.append(Children.begin(), Children.end());
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if (S->isAbstractScope())
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continue;
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for (const InsnRange &R : S->getRanges()) {
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assert(R.first && "InsnRange does not have first instruction!");
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assert(R.second && "InsnRange does not have second instruction!");
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requestLabelBeforeInsn(R.first);
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requestLabelAfterInsn(R.second);
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}
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}
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}
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// Return Label preceding the instruction.
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MCSymbol *DebugHandlerBase::getLabelBeforeInsn(const MachineInstr *MI) {
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MCSymbol *Label = LabelsBeforeInsn.lookup(MI);
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assert(Label && "Didn't insert label before instruction");
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return Label;
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}
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// Return Label immediately following the instruction.
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MCSymbol *DebugHandlerBase::getLabelAfterInsn(const MachineInstr *MI) {
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return LabelsAfterInsn.lookup(MI);
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}
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/// If this type is derived from a base type then return base type size.
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uint64_t DebugHandlerBase::getBaseTypeSize(const DIType *Ty) {
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assert(Ty);
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const DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty);
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if (!DDTy)
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return Ty->getSizeInBits();
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unsigned Tag = DDTy->getTag();
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if (Tag != dwarf::DW_TAG_member && Tag != dwarf::DW_TAG_typedef &&
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Tag != dwarf::DW_TAG_const_type && Tag != dwarf::DW_TAG_volatile_type &&
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Tag != dwarf::DW_TAG_restrict_type && Tag != dwarf::DW_TAG_atomic_type)
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return DDTy->getSizeInBits();
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DIType *BaseType = DDTy->getBaseType();
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if (!BaseType)
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return 0;
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// If this is a derived type, go ahead and get the base type, unless it's a
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// reference then it's just the size of the field. Pointer types have no need
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// of this since they're a different type of qualification on the type.
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if (BaseType->getTag() == dwarf::DW_TAG_reference_type ||
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BaseType->getTag() == dwarf::DW_TAG_rvalue_reference_type)
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return Ty->getSizeInBits();
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return getBaseTypeSize(BaseType);
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}
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bool DebugHandlerBase::isUnsignedDIType(const DIType *Ty) {
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if (auto *CTy = dyn_cast<DICompositeType>(Ty)) {
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// FIXME: Enums without a fixed underlying type have unknown signedness
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// here, leading to incorrectly emitted constants.
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if (CTy->getTag() == dwarf::DW_TAG_enumeration_type)
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return false;
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// (Pieces of) aggregate types that get hacked apart by SROA may be
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// represented by a constant. Encode them as unsigned bytes.
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return true;
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}
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if (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
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dwarf::Tag T = (dwarf::Tag)Ty->getTag();
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// Encode pointer constants as unsigned bytes. This is used at least for
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// null pointer constant emission.
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// FIXME: reference and rvalue_reference /probably/ shouldn't be allowed
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// here, but accept them for now due to a bug in SROA producing bogus
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// dbg.values.
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if (T == dwarf::DW_TAG_pointer_type ||
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T == dwarf::DW_TAG_ptr_to_member_type ||
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T == dwarf::DW_TAG_reference_type ||
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T == dwarf::DW_TAG_rvalue_reference_type)
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return true;
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assert(T == dwarf::DW_TAG_typedef || T == dwarf::DW_TAG_const_type ||
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T == dwarf::DW_TAG_volatile_type ||
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T == dwarf::DW_TAG_restrict_type || T == dwarf::DW_TAG_atomic_type);
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assert(DTy->getBaseType() && "Expected valid base type");
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return isUnsignedDIType(DTy->getBaseType());
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}
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auto *BTy = cast<DIBasicType>(Ty);
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unsigned Encoding = BTy->getEncoding();
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assert((Encoding == dwarf::DW_ATE_unsigned ||
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Encoding == dwarf::DW_ATE_unsigned_char ||
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Encoding == dwarf::DW_ATE_signed ||
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Encoding == dwarf::DW_ATE_signed_char ||
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Encoding == dwarf::DW_ATE_float || Encoding == dwarf::DW_ATE_UTF ||
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Encoding == dwarf::DW_ATE_boolean ||
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(Ty->getTag() == dwarf::DW_TAG_unspecified_type &&
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Ty->getName() == "decltype(nullptr)")) &&
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"Unsupported encoding");
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return Encoding == dwarf::DW_ATE_unsigned ||
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Encoding == dwarf::DW_ATE_unsigned_char ||
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Encoding == dwarf::DW_ATE_UTF || Encoding == dwarf::DW_ATE_boolean ||
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Ty->getTag() == dwarf::DW_TAG_unspecified_type;
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}
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static bool hasDebugInfo(const MachineModuleInfo *MMI,
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const MachineFunction *MF) {
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if (!MMI->hasDebugInfo())
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return false;
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auto *SP = MF->getFunction().getSubprogram();
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if (!SP)
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return false;
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assert(SP->getUnit());
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auto EK = SP->getUnit()->getEmissionKind();
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if (EK == DICompileUnit::NoDebug)
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return false;
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return true;
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}
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void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
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PrevInstBB = nullptr;
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if (!Asm || !hasDebugInfo(MMI, MF)) {
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skippedNonDebugFunction();
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return;
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}
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// Grab the lexical scopes for the function, if we don't have any of those
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// then we're not going to be able to do anything.
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LScopes.initialize(*MF);
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if (LScopes.empty()) {
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beginFunctionImpl(MF);
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return;
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}
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// Make sure that each lexical scope will have a begin/end label.
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identifyScopeMarkers();
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// Calculate history for local variables.
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assert(DbgValues.empty() && "DbgValues map wasn't cleaned!");
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assert(DbgLabels.empty() && "DbgLabels map wasn't cleaned!");
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calculateDbgEntityHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(),
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DbgValues, DbgLabels);
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InstOrdering.initialize(*MF);
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if (TrimVarLocs)
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DbgValues.trimLocationRanges(*MF, LScopes, InstOrdering);
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LLVM_DEBUG(DbgValues.dump());
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// Request labels for the full history.
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for (const auto &I : DbgValues) {
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const auto &Entries = I.second;
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if (Entries.empty())
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continue;
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auto IsDescribedByReg = [](const MachineInstr *MI) {
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return MI->getDebugOperand(0).isReg() && MI->getDebugOperand(0).getReg();
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};
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// The first mention of a function argument gets the CurrentFnBegin label,
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// so arguments are visible when breaking at function entry.
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//
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// We do not change the label for values that are described by registers,
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// as that could place them above their defining instructions. We should
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// ideally not change the labels for constant debug values either, since
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// doing that violates the ranges that are calculated in the history map.
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// However, we currently do not emit debug values for constant arguments
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// directly at the start of the function, so this code is still useful.
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// FIXME: If the first mention of an argument is in a unique section basic
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// block, we cannot always assign the CurrentFnBeginLabel as it lies in a
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// different section. Temporarily, we disable generating loc list
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// information or DW_AT_const_value when the block is in a different
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// section.
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const DILocalVariable *DIVar =
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Entries.front().getInstr()->getDebugVariable();
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if (DIVar->isParameter() &&
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getDISubprogram(DIVar->getScope())->describes(&MF->getFunction()) &&
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Entries.front().getInstr()->getParent()->sameSection(&MF->front())) {
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if (!IsDescribedByReg(Entries.front().getInstr()))
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LabelsBeforeInsn[Entries.front().getInstr()] = Asm->getFunctionBegin();
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if (Entries.front().getInstr()->getDebugExpression()->isFragment()) {
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// Mark all non-overlapping initial fragments.
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for (auto I = Entries.begin(); I != Entries.end(); ++I) {
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if (!I->isDbgValue())
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continue;
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const DIExpression *Fragment = I->getInstr()->getDebugExpression();
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if (std::any_of(Entries.begin(), I,
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[&](DbgValueHistoryMap::Entry Pred) {
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return Pred.isDbgValue() &&
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Fragment->fragmentsOverlap(
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Pred.getInstr()->getDebugExpression());
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}))
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break;
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// The code that generates location lists for DWARF assumes that the
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// entries' start labels are monotonically increasing, and since we
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// don't change the label for fragments that are described by
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// registers, we must bail out when encountering such a fragment.
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if (IsDescribedByReg(I->getInstr()))
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break;
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LabelsBeforeInsn[I->getInstr()] = Asm->getFunctionBegin();
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}
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}
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}
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for (const auto &Entry : Entries) {
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if (Entry.isDbgValue())
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requestLabelBeforeInsn(Entry.getInstr());
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else
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requestLabelAfterInsn(Entry.getInstr());
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}
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}
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// Ensure there is a symbol before DBG_LABEL.
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for (const auto &I : DbgLabels) {
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const MachineInstr *MI = I.second;
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requestLabelBeforeInsn(MI);
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}
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PrevInstLoc = DebugLoc();
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PrevLabel = Asm->getFunctionBegin();
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beginFunctionImpl(MF);
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}
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void DebugHandlerBase::beginInstruction(const MachineInstr *MI) {
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if (!Asm || !MMI->hasDebugInfo())
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return;
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assert(CurMI == nullptr);
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CurMI = MI;
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// Insert labels where requested.
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DenseMap<const MachineInstr *, MCSymbol *>::iterator I =
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LabelsBeforeInsn.find(MI);
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// No label needed.
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if (I == LabelsBeforeInsn.end())
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return;
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// Label already assigned.
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if (I->second)
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return;
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if (!PrevLabel) {
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PrevLabel = MMI->getContext().createTempSymbol();
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Asm->OutStreamer->emitLabel(PrevLabel);
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}
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I->second = PrevLabel;
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}
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void DebugHandlerBase::endInstruction() {
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if (!Asm || !MMI->hasDebugInfo())
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return;
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|
|
||
|
|
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 (Asm && hasDebugInfo(MMI, MF))
|
||
|
|
endFunctionImpl(MF);
|
||
|
|
DbgValues.clear();
|
||
|
|
DbgLabels.clear();
|
||
|
|
LabelsBeforeInsn.clear();
|
||
|
|
LabelsAfterInsn.clear();
|
||
|
|
InstOrdering.clear();
|
||
|
|
}
|
||
|
|
|
||
|
|
void DebugHandlerBase::beginBasicBlock(const MachineBasicBlock &MBB) {
|
||
|
|
if (!MBB.isBeginSection())
|
||
|
|
return;
|
||
|
|
|
||
|
|
PrevLabel = MBB.getSymbol();
|
||
|
|
}
|
||
|
|
|
||
|
|
void DebugHandlerBase::endBasicBlock(const MachineBasicBlock &MBB) {
|
||
|
|
if (!MBB.isEndSection())
|
||
|
|
return;
|
||
|
|
|
||
|
|
PrevLabel = nullptr;
|
||
|
|
}
|