[ObjectYAML] [COFF] Support multiple symbols with the same name

Differential Revision: https://reviews.llvm.org/D56294

llvm-svn: 350566

llvm/include/llvm/ObjectYAML/COFFYAML.h

@@ -58,7 +58,13 @@ LLVM_YAML_STRONG_TYPEDEF(uint8_t, AuxSymbolType)
 struct Relocation {
   uint32_t VirtualAddress;
   uint16_t Type;
+
+  // Normally a Relocation can refer to the symbol via its name.
+  // It can also use a direct symbol table index instead (with no name
+  // specified), allowing disambiguating between multiple symbols with the
+  // same name or crafting intentionally broken files for testing.
   StringRef SymbolName;
+  Optional<uint32_t> SymbolTableIndex;
 };
 
 struct Section {

llvm/lib/ObjectYAML/COFFYAML.cpp

@@ -407,7 +407,8 @@ struct NDLLCharacteristics {
 void MappingTraits<COFFYAML::Relocation>::mapping(IO &IO,
                                                   COFFYAML::Relocation &Rel) {
   IO.mapRequired("VirtualAddress", Rel.VirtualAddress);
-  IO.mapRequired("SymbolName", Rel.SymbolName);
+  IO.mapOptional("SymbolName", Rel.SymbolName, StringRef());
+  IO.mapOptional("SymbolTableIndex", Rel.SymbolTableIndex);
 
   COFF::header &H = *static_cast<COFF::header *>(IO.getContext());
   if (H.Machine == COFF::IMAGE_FILE_MACHINE_I386) {

llvm/test/tools/yaml2obj/coff-symbol-index.yaml

@@ -0,0 +1,74 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readobj -relocations %t | FileCheck %s --check-prefix=RELOCS
+# RUN: obj2yaml %t | FileCheck %s --check-prefix=YAML
+
+# RELOCS:      Relocations [
+# RELOCS-NEXT:   Section (1) .text {
+# RELOCS-NEXT:     0x3 IMAGE_REL_AMD64_REL32 .rdata (0)
+# RELOCS-NEXT:     0xA IMAGE_REL_AMD64_REL32 .rdata (1)
+# RELOCS-NEXT:     0x11 IMAGE_REL_AMD64_REL32 foo (2)
+# RELOCS-NEXT:   }
+# RELOCS-NEXT: ]
+
+# Check that we usually output relocations with SymbolName.
+# For relocations with a non-unique symbol name, output
+# SymbolTableIndex instead.
+
+# YAML:          Relocations:     
+# YAML-NEXT:       - VirtualAddress:  3
+# YAML-NEXT:         SymbolTableIndex: 0
+# YAML-NEXT:         Type:            IMAGE_REL_AMD64_REL32
+# YAML-NEXT:       - VirtualAddress:  10
+# YAML-NEXT:         SymbolTableIndex: 1
+# YAML-NEXT:         Type:            IMAGE_REL_AMD64_REL32
+# YAML-NEXT:       - VirtualAddress:  17
+# YAML-NEXT:         SymbolName:      foo
+# YAML-NEXT:         Type:            IMAGE_REL_AMD64_REL32
+
+--- !COFF
+header:          
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:        
+  - Name:            .text
+    Characteristics: [  ]
+    Alignment:       4
+    SectionData:     488B0500000000488B0500000000488B0500000000
+    Relocations:     
+      - VirtualAddress:  3
+        SymbolTableIndex: 0
+        Type:            IMAGE_REL_AMD64_REL32
+      - VirtualAddress:  10
+        SymbolTableIndex: 1
+        Type:            IMAGE_REL_AMD64_REL32
+      - VirtualAddress:  17
+        SymbolName:      foo
+        Type:            IMAGE_REL_AMD64_REL32
+  - Name:            .rdata
+    Characteristics: [  ]
+    Alignment:       1
+    SectionData:     '00'
+  - Name:            .rdata
+    Characteristics: [  ]
+    Alignment:       1
+    SectionData:     '01'
+symbols:         
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+  - Name:            foo
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/tools/obj2yaml/coff2yaml.cpp

@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "obj2yaml.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/DebugInfo/CodeView/DebugChecksumsSubsection.h"
 #include "llvm/DebugInfo/CodeView/DebugStringTableSubsection.h"
 #include "llvm/DebugInfo/CodeView/StringsAndChecksums.h"
@@ -142,6 +143,18 @@ void COFFDumper::dumpSections(unsigned NumSections) {
   codeview::StringsAndChecksumsRef SC;
   initializeFileAndStringTable(Obj, SC);
 
+  StringMap<bool> SymbolUnique;
+  for (const auto &S : Obj.symbols()) {
+    object::COFFSymbolRef Symbol = Obj.getCOFFSymbol(S);
+    StringRef Name;
+    Obj.getSymbolName(Symbol, Name);
+    StringMap<bool>::iterator It;
+    bool Inserted;
+    std::tie(It, Inserted) = SymbolUnique.insert(std::make_pair(Name, true));
+    if (!Inserted)
+      It->second = false;
+  }
+
   for (const auto &ObjSection : Obj.sections()) {
     const object::coff_section *COFFSection = Obj.getCOFFSection(ObjSection);
     COFFYAML::Section NewYAMLSection;
@@ -192,7 +205,10 @@ void COFFDumper::dumpSections(unsigned NumSections) {
        OS.flush();
        report_fatal_error(Buf);
       }
-      Rel.SymbolName = *SymbolNameOrErr;
+      if (SymbolUnique.lookup(*SymbolNameOrErr))
+        Rel.SymbolName = *SymbolNameOrErr;
+      else
+        Rel.SymbolTableIndex = reloc->SymbolTableIndex;
       Rel.VirtualAddress = reloc->VirtualAddress;
       Rel.Type = reloc->Type;
       Relocations.push_back(Rel);

llvm/tools/yaml2obj/yaml2coff.cpp

@@ -24,6 +24,7 @@
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/WithColor.h"
 #include "llvm/Support/raw_ostream.h"
 #include <vector>
 
@@ -520,7 +521,15 @@ static bool writeCOFF(COFFParser &CP, raw_ostream &OS) {
     assert(S.Header.SizeOfRawData >= S.SectionData.binary_size());
     OS << num_zeros(S.Header.SizeOfRawData - S.SectionData.binary_size());
     for (const COFFYAML::Relocation &R : S.Relocations) {
-      uint32_t SymbolTableIndex = SymbolTableIndexMap[R.SymbolName];
+      uint32_t SymbolTableIndex;
+      if (R.SymbolTableIndex) {
+        if (!R.SymbolName.empty())
+          WithColor::error()
+              << "Both SymbolName and SymbolTableIndex specified\n";
+        SymbolTableIndex = *R.SymbolTableIndex;
+      } else {
+        SymbolTableIndex = SymbolTableIndexMap[R.SymbolName];
+      }
       OS << binary_le(R.VirtualAddress)
          << binary_le(SymbolTableIndex)
          << binary_le(R.Type);