[MC/AsmParser] Avoid setting MCSymbol.IsUsed in some cases

[oota-llvm.git] / lib / MC / StringTableBuilder.cpp

diff --git a/lib/MC/StringTableBuilder.cpp b/lib/MC/StringTableBuilder.cpp
index 2343845ee326bcf20cc53ea8f95aab22d58e58aa..9de9363611e67ee3510f427d3bd6492ae375a12f 100644 (file)
--- a/lib/MC/StringTableBuilder.cpp
+++ b/lib/MC/StringTableBuilder.cpp
@@ -9,27 +9,50 @@
 
 #include "llvm/MC/StringTableBuilder.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/COFF.h"
+#include "llvm/Support/Endian.h"
 
 using namespace llvm;
 
-void StringTableBuilder::finalize() {
+static bool compareBySuffix(StringRef a, StringRef b) {
+  size_t sizeA = a.size();
+  size_t sizeB = b.size();
+  size_t len = std::min(sizeA, sizeB);
+  for (size_t i = 0; i < len; ++i) {
+    char ca = a[sizeA - i - 1];
+    char cb = b[sizeB - i - 1];
+    if (ca != cb)
+      return ca > cb;
+  }
+  return sizeA > sizeB;
+}
+
+void StringTableBuilder::finalize(Kind kind) {
   SmallVector<StringRef, 8> Strings;
+  Strings.reserve(StringIndexMap.size());
+
   for (auto i = StringIndexMap.begin(), e = StringIndexMap.end(); i != e; ++i)
     Strings.push_back(i->getKey());
 
-  // Sort the vector so a string is sorted above its suffixes.
-  std::sort(Strings.begin(), Strings.end(), [](StringRef A, StringRef B) {
-    typedef std::reverse_iterator<StringRef::iterator> Reverse;
-    return !std::lexicographical_compare(Reverse(A.end()), Reverse(A.begin()),
-                                         Reverse(B.end()), Reverse(B.begin()));
-  });
+  std::sort(Strings.begin(), Strings.end(), compareBySuffix);
 
-  // FIXME: Starting with a null byte is ELF specific. Generalize this so we
-  // can use the class with other object formats.
-  StringTable += '\x00';
+  switch (kind) {
+  case ELF:
+  case MachO:
+    // Start the table with a NUL byte.
+    StringTable += '\x00';
+    break;
+  case WinCOFF:
+    // Make room to write the table size later.
+    StringTable.append(4, '\x00');
+    break;
+  }
 
   StringRef Previous;
   for (StringRef s : Strings) {
+    if (kind == WinCOFF)
+      assert(s.size() > COFF::NameSize && "Short string in COFF string table!");
+
     if (Previous.endswith(s)) {
       StringIndexMap[s] = StringTable.size() - 1 - s.size();
       continue;
@@ -40,4 +63,26 @@ void StringTableBuilder::finalize() {
     StringTable += '\x00';
     Previous = s;
   }
+
+  switch (kind) {
+  case ELF:
+    break;
+  case MachO:
+    // Pad to multiple of 4.
+    while (StringTable.size() % 4)
+      StringTable += '\x00';
+    break;
+  case WinCOFF:
+    // Write the table size in the first word.
+    assert(StringTable.size() <= std::numeric_limits<uint32_t>::max());
+    uint32_t size = static_cast<uint32_t>(StringTable.size());
+    support::endian::write<uint32_t, support::little, support::unaligned>(
+        StringTable.data(), size);
+    break;
+  }
+}
+
+void StringTableBuilder::clear() {
+  StringTable.clear();
+  StringIndexMap.clear();
 }