llvm-dwp: provide diagnostics for duplicate DWO IDs

These diagnostics aren't perfect - in the case of merging several dwos
into dwps and those dwps into more dwps - just getting the message about
the original source file name might not be much help (since it's the
same in both dwos, by definition - but doesn't tell you which chain of
dwps to backtrack)

It might be worth adding the DW_AT_dwo_id to the split debug info to
improve the diagnostic experience - might help track down the duplicates
better.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261988 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/llvm-dwp/X86/duplicate.test

@@ -0,0 +1,18 @@
+RUN: not llvm-dwp %p/../Inputs/duplicate/c.dwo %p/../Inputs/duplicate/c.dwo -o %t 2>&1 \
+RUN:   | FileCheck --check-prefix=CHECK %s
+
+RUN: not llvm-dwp %p/../Inputs/duplicate/c.dwo %p/../Inputs/duplicate/bc.dwp -o %t 2>&1 \
+RUN:   | FileCheck --check-prefix=CHECK --check-prefix=DWP2 %s
+
+RUN: not llvm-dwp %p/../Inputs/duplicate/ac.dwp %p/../Inputs/duplicate/c.dwo -o %t 2>&1 \
+RUN:   | FileCheck --check-prefix=CHECK --check-prefix=DWP1 %s
+
+RUN: not llvm-dwp %p/../Inputs/duplicate/ac.dwp %p/../Inputs/duplicate/bc.dwp -o %t 2>&1 \
+RUN:   | FileCheck --check-prefix=CHECK --check-prefix=DWP1 --check-prefix=DWP2 %s
+
+Build from a, b, and c.c all containing a single void() func by the name of the file.
+
+CHECK: Duplicate DWO ID ({{.*}}) in 'c.c'
+DWP1-SAME: (from '{{.*}}ac.dwp')
+CHECK-SAME: and 'c.c'
+DWP2-SAME: (from '{{.*}}bc.dwp')

tools/llvm-dwp/llvm-dwp.cpp

@@ -24,6 +24,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
 #include <list>
+#include <iostream>
 #include <memory>
 #include <system_error>
 #include <unordered_set>
@@ -106,6 +107,43 @@ static uint32_t getCUAbbrev(StringRef Abbrev, uint64_t AbbrCode) {
   return Offset;
 }
 
+static const char *getCUName(StringRef Abbrev, StringRef Info,
+                             StringRef StrOffsets, StringRef Str) {
+  uint32_t Offset = 0;
+  DataExtractor InfoData(Info, true, 0);
+  InfoData.getU32(&Offset); // Length
+  uint16_t Version = InfoData.getU16(&Offset);
+  InfoData.getU32(&Offset); // Abbrev offset (should be zero)
+  uint8_t AddrSize = InfoData.getU8(&Offset);
+
+  uint32_t AbbrCode = InfoData.getULEB128(&Offset);
+
+  DataExtractor AbbrevData(Abbrev, true, 0);
+  uint32_t AbbrevOffset = getCUAbbrev(Abbrev, AbbrCode);
+  uint64_t Tag = AbbrevData.getULEB128(&AbbrevOffset);
+  (void)Tag;
+  // FIXME: Real error handling
+  assert(Tag == dwarf::DW_TAG_compile_unit);
+  // DW_CHILDREN
+  AbbrevData.getU8(&AbbrevOffset);
+  uint32_t Name;
+  uint32_t Form;
+  while ((Name = AbbrevData.getULEB128(&AbbrevOffset)) |
+             (Form = AbbrevData.getULEB128(&AbbrevOffset)) &&
+         Name != dwarf::DW_AT_name) {
+    DWARFFormValue::skipValue(Form, InfoData, &Offset, Version, AddrSize);
+  }
+  // FIXME: Real error handling
+  assert(Name == dwarf::DW_AT_name);
+  auto StrIndex = InfoData.getULEB128(&Offset);
+
+  DataExtractor StrOffsetsData(StrOffsets, true, 0);
+  uint32_t StrOffsetsOffset = 4 * StrIndex;
+  uint32_t StrOffset = StrOffsetsData.getU32(&StrOffsetsOffset);
+  DataExtractor StrData(Str, true, 0);
+  return StrData.getCStr(&StrOffset);
+}
+
 static uint64_t getCUSignature(StringRef Abbrev, StringRef Info) {
   uint32_t Offset = 0;
   DataExtractor InfoData(Info, true, 0);
@@ -138,8 +176,17 @@ static uint64_t getCUSignature(StringRef Abbrev, StringRef Info) {
 
 struct UnitIndexEntry {
   DWARFUnitIndex::Entry::SectionContribution Contributions[8];
+  std::string Name;
+  StringRef DWPName;
 };
 
+StringRef getSubsection(StringRef Section, const DWARFUnitIndex::Entry &Entry, DWARFSectionKind Kind) {
+  const auto *Off = Entry.getOffset(Kind);
+  if (!Off)
+    return StringRef();
+  return Section.substr(Off->Offset, Off->Length);
+}
+
 static void addAllTypesFromDWP(
     MCStreamer &Out, MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
     const DWARFUnitIndex &TUIndex, MCSection *OutputTypes, StringRef Types,
@@ -416,8 +463,22 @@ static std::error_code write(MCStreamer &Out, ArrayRef<std::string> Inputs) {
           continue;
         auto P =
             IndexEntries.insert(std::make_pair(E.getSignature(), CurEntry));
-        // FIXME: Check P.second and error for duplicate CU signatures
+        const char* Name = getCUName(
+            getSubsection(AbbrevSection, E, DW_SECT_ABBREV),
+            getSubsection(InfoSection, E, DW_SECT_INFO),
+            getSubsection(CurStrOffsetSection, E, DW_SECT_STR_OFFSETS),
+            CurStrSection);
+        if (!P.second) {
+          auto &PrevE = *P.first;
+          std::cerr << "Duplicate DWO ID (" << PrevE.first << ") in '" << PrevE.second.Name << "' ";
+          if (!PrevE.second.DWPName.empty())
+            std::cerr << "(from '" << PrevE.second.DWPName.str() << "') ";
+          std::cerr << "and '" << Name << "' (from '" << Input << "')\n";
+          return make_error_code(std::errc::invalid_argument);
+        }
         auto &NewEntry = P.first->second;
+        NewEntry.Name = Name;
+        NewEntry.DWPName = Input;
         for (auto Kind : CUIndex.getColumnKinds()) {
           auto &C = NewEntry.Contributions[Kind - DW_SECT_INFO];
           C.Offset += I->Offset;
@@ -439,9 +500,20 @@ static std::error_code write(MCStreamer &Out, ArrayRef<std::string> Inputs) {
                            ContributionOffsets[DW_SECT_TYPES - DW_SECT_INFO]);
       }
     } else {
-      IndexEntries.insert(
+      auto P = IndexEntries.insert(
           std::make_pair(getCUSignature(AbbrevSection, InfoSection), CurEntry));
-      // FIXME: Check P.second and error for duplicate CU signatures
+      const char *Name = getCUName(AbbrevSection, InfoSection,
+                                   CurStrOffsetSection, CurStrSection);
+      if (!P.second) {
+        auto &E = *P.first;
+        std::cerr << "Duplicate DWO ID (" << E.first << ") in '" << Name
+                  << "' ";
+        if (!E.second.DWPName.empty())
+          std::cerr << "(from '" << E.second.DWPName.str() << "') ";
+        std::cerr << "and '" << E.second.Name << "'\n";
+        return make_error_code(std::errc::invalid_argument);
+      }
+      P.first->second.Name = Name;
       addAllTypes(Out, TypeIndexEntries, TypesSection, CurTypesSection,
                   CurEntry, ContributionOffsets[DW_SECT_TYPES - DW_SECT_INFO]);
     }