[InstrProf][correlation] Read DWARFv5 `OP_addrx` location

[ellis]

Summary

Correctly read OP_addrx type encodings for DWARFv5 locations.

[ellis]

The original crash is here https://github.com/llvm/llvm-project/issues/53387

[dblaikie]

llvm/lib/ProfileData/InstrProfCorrelator.cpp

131–134

This should probably be committed separately & ideally with a test case.

187–193

Could you use DWARFUnit::getAddrOffsetSectionItem, perhaps?

(& I guess this would be committed along with an additional test case that covers DWARFv5 or swapping back the temporary change for the existing test case (probably should keep some v4 coverage too, for the DW_OP_addr case above))

[ellis]

Simplify code and add test

[ellis]

llvm/lib/ProfileData/InstrProfCorrelator.cpp

187–193

Ah thanks, that makes the code much simpler!

[dblaikie]

Looks good, thanks!

llvm/lib/ProfileData/InstrProfCorrelator.cpp

 //===-- InstrProfCorrelator.cpp -------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ProfileData/InstrProfCorrelator.h"
+#include "llvm/DebugInfo/DWARF/DWARFDebugAddr.h"
 #include "llvm/Object/MachO.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 
 #define DEBUG_TYPE "correlator"
 
 using namespace llvm;
InstrProfCorrelatorImpl<IntPtrT>::get(
   }
   return make_error<InstrProfError>(instrprof_error::unsupported_debug_format);
 }
 
 template <class IntPtrT>
 Error InstrProfCorrelatorImpl<IntPtrT>::correlateProfileData() {
   assert(Data.empty() && CompressedNames.empty() && Names.empty());
   correlateProfileDataImpl();
+  if (Data.empty() || Names.empty())
+    return make_error<InstrProfError>(
+        instrprof_error::unable_to_correlate_profile,
+        "could not find any profile metadata in debug info");
   auto Result =
       collectPGOFuncNameStrings(Names, /*doCompression=*/true, CompressedNames);
   CounterOffsets.clear();
   Names.clear();
   return Result;
 }
 
 template <class IntPtrT>

 llvm::Optional<uint64_t>
 DwarfInstrProfCorrelator<IntPtrT>::getLocation(const DWARFDie &Die) const {
   auto Locations = Die.getLocations(dwarf::DW_AT_location);
   if (!Locations) {
     consumeError(Locations.takeError());
     return {};
   }
   auto &DU = *Die.getDwarfUnit();
-  for (auto &Location : *Locations) {
-    auto AddressSize = DU.getAddressByteSize();
-    DataExtractor Data(Location.Expr, DICtx->isLittleEndian(), AddressSize);
+  bool isLE = DICtx->isLittleEndian();
+  const auto &DObj = DICtx->getDWARFObj();
+  DWARFDataExtractor AddrSectionData(DObj, DObj.getAddrSection(), isLE,
+                                     AddressSize);
+  for (auto &Location : *Locations) {
+    DataExtractor Data(Location.Expr, isLE, AddressSize);
     DWARFExpression Expr(Data, AddressSize);
-    for (auto &Op : Expr)
-      if (Op.getCode() == dwarf::DW_OP_addr)
+    for (auto &Op : Expr) {
+      if (Op.getCode() == dwarf::DW_OP_addr) {
         return Op.getRawOperand(0);
+      } else if (Op.getCode() == dwarf::DW_OP_addrx) {
+        uint64_t Index = Op.getRawOperand(0);
+        auto Offset = DU.getAddrOffsetSectionBase();
+        if (!Offset.hasValue())
+          continue;
+        // FIXME: Perhaps we should be using DWARFDebugAddrTable
+        uint64_t RawOffset = *Offset + Index * AddressSize;
+        return AddrSectionData.getAddress(&RawOffset);
+      }
+    }
   }
   return {};
 }
 
 template <class IntPtrT>
 bool DwarfInstrProfCorrelator<IntPtrT>::isDIEOfProbe(const DWARFDie &Die) {
   const auto &ParentDie = Die.getParent();
   if (!Die.isValid() || !ParentDie.isValid() || Die.isNULL())