Utils.h

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//===- Utils.h --------------------------------------------------*- 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
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_DWARFLINKER_UTILS_H
#define LLVM_DWARFLINKER_UTILS_H
 
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
 
namespace llvm {
class DWARFDie;
 
namespace dwarf_linker {
 
/// Test if the location of variable \p Die contains a global address
/// but only uses to compute the variable's value, for example
/// DW_OP_addr DW_OP_stack_value.
LLVM_ABI bool hasImplicitAddressLocation(const DWARFDie &Die);
 
/// Test if the DW_TAG_member \p Die is a DWARF 2-4 style static data member: a
/// declaration with no storage in the record. DWARF 5 uses a DW_TAG_variable
/// instead.
LLVM_ABI bool isStaticDataMember(const DWARFDie &Die);
 
/// Test if an unnamed type with tag \p Tag is identified by its children, which
/// tell it apart from other unnamed types declared on the same line. Other
/// unnamed types, like pointer types, have no such children.
LLVM_ABI bool isIdentifiedByChildren(dwarf::Tag Tag);
 
/// Test if \p Die is a child that identifies its unnamed parent type.
LLVM_ABI bool isIdentifyingChild(const DWARFDie &Die);
 
/// Build a map from an input DW_AT_LLVM_stmt_sequence byte offset to
/// the first-row index (in \p LT.Rows) of the corresponding line-table
/// sequence. Seeds the map from \p LT.Sequences (the DWARF parser's
/// discovered sequences), then augments it by walking row boundaries
/// (DW_LNE_end_sequence markers) and matching them against the sorted
/// input offsets in \p SortedStmtSeqOffsets, using the parser's results
/// as ground-truth anchors. This recovers sequences the parser may not
/// have registered and keeps the classic and parallel DWARFLinkers in
/// lockstep. Caller passes \p SortedStmtSeqOffsets sorted ascending
/// and deduplicated.
LLVM_ABI void buildStmtSeqOffsetToFirstRowIndex(
    const DWARFDebugLine::LineTable &LT,
    ArrayRef<uint64_t> SortedStmtSeqOffsets,
    DenseMap<uint64_t, uint64_t> &SeqOffToFirstRow);
 
/// This function calls \p Iteration() until it returns false.
/// If number of iterations exceeds \p MaxCounter then an Error is returned.
/// This function should be used for loops which assumed to have number of
/// iterations significantly smaller than \p MaxCounter to avoid infinite
/// looping in error cases.
inline Error finiteLoop(function_ref<Expected<bool>()> Iteration,
                        size_t MaxCounter = 100000) {
  size_t iterationsCounter = 0;
  while (iterationsCounter++ < MaxCounter) {
    Expected<bool> IterationResultOrError = Iteration();
    if (!IterationResultOrError)
      return IterationResultOrError.takeError();
    if (!IterationResultOrError.get())
      return Error::success();
  }
  return createStringError(std::errc::invalid_argument, "Infinite recursion");
}
 
/// Make a best effort to guess the
/// Xcode.app/Contents/Developer path from an SDK path.
inline StringRef guessDeveloperDir(StringRef SysRoot) {
  // Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk
  auto it = sys::path::rbegin(SysRoot);
  auto end = sys::path::rend(SysRoot);
  if (it == end || !it->ends_with(".sdk"))
    return {};
  ++it;
  // Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs
  if (it == end || *it != "SDKs")
    return {};
  auto developerEnd = it;
  ++it;
  while (it != end) {
    // Contents/Developer/Platforms/MacOSX.platform/Developer
    if (*it != "Developer")
      return {};
    ++it;
    if (it == end)
      return {};
    if (*it == "Contents")
      return StringRef(SysRoot.data(),
                       developerEnd - sys::path::rend(SysRoot) - 1);
    // Contents/Developer/Platforms/MacOSX.platform
    if (!it->ends_with(".platform"))
      return {};
    ++it;
    // Contents/Developer/Platforms
    if (it == end || *it != "Platforms")
      return {};
    developerEnd = it;
    ++it;
  }
  return {};
}
 
/// Make a best effort to determine whether Path is inside a toolchain.
inline bool isInToolchainDir(StringRef Path) {
  // Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-05-15-a.xctoolchain/usr/lib/swift/macosx/_StringProcessing.swiftmodule/arm64-apple-macos.private.swiftinterface
  for (auto it = sys::path::rbegin(Path), end = sys::path::rend(Path);
       it != end; ++it) {
    if (it->ends_with(".xctoolchain")) {
      ++it;
      if (it == end)
        return false;
      if (*it != "Toolchains")
        return false;
      ++it;
      if (it == end)
        return false;
      if (*it != "Developer")
        return false;
      return true;
    }
  }
  return false;
}
 
inline bool isPathAbsoluteOnWindowsOrPosix(const Twine &Path) {
  // Debug info can contain paths from any OS, not necessarily
  // an OS we're currently running on. Moreover different compilation units can
  // be compiled on different operating systems and linked together later.
  return sys::path::is_absolute(Path, sys::path::Style::posix) ||
         sys::path::is_absolute(Path, sys::path::Style::windows);
}
 
} // end of namespace dwarf_linker
} // end of namespace llvm
 
#endif // LLVM_DWARFLINKER_UTILS_H