[PECOFF] Use std::set to store export symbol descriptors.

Each export symbol descriptor has unique name attribute, so std::set is
better container than std::vector for it. No functionality change.

llvm-svn: 198102

lld/include/lld/ReaderWriter/PECOFFLinkingContext.h

@@ -59,6 +59,10 @@ public:
 
   struct ExportDesc {
     ExportDesc() : ordinal(-1), noname(false), isData(false) {}
+    bool operator<(const ExportDesc &other) const {
+      return name.compare(other.name) < 0;
+    }
+
     std::string name;
     int ordinal;
     bool noname;
@@ -218,8 +222,8 @@ public:
   ArrayRef<uint8_t> getDosStub() const { return _dosStub; }
 
   void addDllExport(ExportDesc &desc);
-  std::vector<ExportDesc> &getDllExports() { return _dllExports; }
-  const std::vector<ExportDesc> &getDllExports() const { return _dllExports; }
+  std::set<ExportDesc> &getDllExports() { return _dllExports; }
+  const std::set<ExportDesc> &getDllExports() const { return _dllExports; }
 
   StringRef allocate(StringRef ref) const {
     char *x = _allocator.Allocate<char>(ref.size() + 1);
@@ -299,8 +303,7 @@ private:
   std::map<std::string, uint32_t> _sectionClearMask;
 
   // DLLExport'ed symbols.
-  std::vector<ExportDesc> _dllExports;
-  std::set<StringRef> _dllExportSet;
+  std::set<ExportDesc> _dllExports;
 
   // List of files that will be removed on destruction.
   std::vector<std::unique_ptr<llvm::FileRemover> > _tempFiles;

lld/lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp

@@ -33,13 +33,17 @@
 namespace lld {
 
 static void assignOrdinals(PECOFFLinkingContext &ctx) {
+  std::set<PECOFFLinkingContext::ExportDesc> exports;
   int maxOrdinal = -1;
   for (const PECOFFLinkingContext::ExportDesc &desc : ctx.getDllExports())
     maxOrdinal = std::max(maxOrdinal, desc.ordinal);
   int nextOrdinal = (maxOrdinal == -1) ? 1 : (maxOrdinal + 1);
-  for (PECOFFLinkingContext::ExportDesc &desc : ctx.getDllExports())
+  for (PECOFFLinkingContext::ExportDesc desc : ctx.getDllExports()) {
     if (desc.ordinal == -1)
       desc.ordinal = nextOrdinal++;
+    exports.insert(desc);
+  }
+  ctx.getDllExports().swap(exports);
 }
 
 bool PECOFFLinkingContext::validateImpl(raw_ostream &diagnostics) {
@@ -245,13 +249,12 @@ uint32_t PECOFFLinkingContext::getSectionAttributes(StringRef sectionName,
 }
 
 void PECOFFLinkingContext::addDllExport(ExportDesc &desc) {
-  if (_dllExportSet.count(desc.name)) {
+  auto exists = _dllExports.insert(desc);
+  if (!exists.second) {
     llvm::errs() << "Export symbol '" << desc.name
                  << "' specified more than once.\n";
     return;
   }
-  _dllExports.push_back(desc);
-  _dllExportSet.insert(_dllExports.back().name);
 }
 
 void PECOFFLinkingContext::addPasses(PassManager &pm) {

lld/unittests/DriverTests/WinLinkDriverTest.cpp

@@ -18,6 +18,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/COFF.h"
 
+#include <set>
 #include <vector>
 
 using namespace llvm;
@@ -158,39 +159,43 @@ TEST_F(WinLinkParserTest, AlternateName) {
 
 TEST_F(WinLinkParserTest, Export) {
   EXPECT_TRUE(parse("link.exe", "/export:foo", "a.out", nullptr));
-  const std::vector<PECOFFLinkingContext::ExportDesc> &exports =
+  const std::set<PECOFFLinkingContext::ExportDesc> &exports =
       _context.getDllExports();
   EXPECT_EQ(1U, exports.size());
-  EXPECT_EQ("_foo", exports[0].name);
-  EXPECT_EQ(1, exports[0].ordinal);
-  EXPECT_FALSE(exports[0].noname);
-  EXPECT_FALSE(exports[0].isData);
+  auto it = exports.begin();
+  EXPECT_EQ("_foo", it->name);
+  EXPECT_EQ(1, it->ordinal);
+  EXPECT_FALSE(it->noname);
+  EXPECT_FALSE(it->isData);
 }
 
 TEST_F(WinLinkParserTest, ExportWithOptions) {
   EXPECT_TRUE(parse("link.exe", "/export:foo,@8,noname,data",
                     "/export:bar,@10,data", "a.out", nullptr));
-  const std::vector<PECOFFLinkingContext::ExportDesc> &exports =
+  const std::set<PECOFFLinkingContext::ExportDesc> &exports =
       _context.getDllExports();
   EXPECT_EQ(2U, exports.size());
-  EXPECT_EQ("_foo", exports[0].name);
-  EXPECT_EQ(8, exports[0].ordinal);
-  EXPECT_TRUE(exports[0].noname);
-  EXPECT_TRUE(exports[0].isData);
-  EXPECT_EQ("_bar", exports[1].name);
-  EXPECT_EQ(10, exports[1].ordinal);
-  EXPECT_FALSE(exports[1].noname);
-  EXPECT_TRUE(exports[1].isData);
+  auto it = exports.begin();
+  EXPECT_EQ("_bar", it->name);
+  EXPECT_EQ(10, it->ordinal);
+  EXPECT_FALSE(it->noname);
+  EXPECT_TRUE(it->isData);
+  ++it;
+  EXPECT_EQ("_foo", it->name);
+  EXPECT_EQ(8, it->ordinal);
+  EXPECT_TRUE(it->noname);
+  EXPECT_TRUE(it->isData);
 }
 
 TEST_F(WinLinkParserTest, ExportDuplicateExports) {
   EXPECT_TRUE(
       parse("link.exe", "/export:foo,@1", "/export:foo,@2", "a.out", nullptr));
-  const std::vector<PECOFFLinkingContext::ExportDesc> &exports =
+  const std::set<PECOFFLinkingContext::ExportDesc> &exports =
       _context.getDllExports();
   EXPECT_EQ(1U, exports.size());
-  EXPECT_EQ("_foo", exports[0].name);
-  EXPECT_EQ(1, exports[0].ordinal);
+  auto it = exports.begin();
+  EXPECT_EQ("_foo", it->name);
+  EXPECT_EQ(1, it->ordinal);
 }
 
 TEST_F(WinLinkParserTest, ExportDuplicateOrdinals) {