Centralize the handling of unique ids for temporary labels.

Before this patch code wanting to create temporary labels for a given entity
(function, cu, exception range, etc) had to keep its own counter to have stable
symbol names.

createTempSymbol would still add a suffix to make sure a new symbol was always
returned, but it kept a single counter. Because of that, if we were to use
just createTempSymbol("cu_begin"), the label could change from cu_begin42 to
cu_begin43 because some other code started using temporary labels.

Simplify this by just keeping one counter per prefix and removing the various
specialized counters.

llvm-svn: 232535

1 files changed, 31 insertions, 32 deletions

diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index b0e7cf50d69..3cb3ea12afd 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -34,7 +34,7 @@ MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
                      bool DoAutoReset)
     : SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi), Allocator(),
-      Symbols(Allocator), UsedNames(Allocator), NextUniqueID(0),
+      Symbols(Allocator), UsedNames(Allocator),
       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0), DwarfLocSeen(false),
       GenDwarfForAssembly(false), GenDwarfFileNumber(0), DwarfVersion(4),
       AllowTemporaryLabels(true), DwarfCompileUnitID(0),
@@ -87,7 +87,7 @@ void MCContext::reset() {
   ELFUniquingMap.clear();
   COFFUniquingMap.clear();
 
-  NextUniqueID = 0;
+  NextID.clear();
   AllowTemporaryLabels = true;
   DwarfLocSeen = false;
   GenDwarfForAssembly = false;
@@ -106,7 +106,7 @@ MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
 
   MCSymbol *&Sym = Symbols[NameRef];
   if (!Sym)
-    Sym = CreateSymbol(NameRef);
+    Sym = CreateSymbol(NameRef, false);
 
   return Sym;
 }
@@ -139,49 +139,48 @@ MCSymbol *MCContext::getOrCreateFrameAllocSymbol(StringRef FuncName,
                            "$frame_escape_" + Twine(Idx));
 }
 
-MCSymbol *MCContext::CreateSymbol(StringRef Name) {
+MCSymbol *MCContext::CreateSymbol(StringRef Name, bool AlwaysAddSuffix) {
   // Determine whether this is an assembler temporary or normal label, if used.
-  bool isTemporary = false;
+  bool IsTemporary = false;
   if (AllowTemporaryLabels)
-    isTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
+    IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
 
-  auto NameEntry = UsedNames.insert(std::make_pair(Name, true));
-  if (!NameEntry.second) {
-    assert(isTemporary && "Cannot rename non-temporary symbols");
-    SmallString<128> NewName = Name;
-    do {
+  SmallString<128> NewName = Name;
+  bool AddSuffix = AlwaysAddSuffix;
+  unsigned &NextUniqueID = NextID[Name];
+  for (;;) {
+    if (AddSuffix) {
       NewName.resize(Name.size());
       raw_svector_ostream(NewName) << NextUniqueID++;
-      NameEntry = UsedNames.insert(std::make_pair(NewName, true));
-    } while (!NameEntry.second);
+    }
+    auto NameEntry = UsedNames.insert(std::make_pair(NewName, true));
+    if (NameEntry.second) {
+      // Ok, we found a name. Have the MCSymbol object itself refer to the copy
+      // of the string that is embedded in the UsedNames entry.
+      MCSymbol *Result =
+          new (*this) MCSymbol(NameEntry.first->getKey(), IsTemporary);
+      return Result;
+    }
+    assert(IsTemporary && "Cannot rename non-temporary symbols");
+    AddSuffix = true;
   }
-
-  // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
-  // to the copy of the string that is embedded in the UsedNames entry.
-  MCSymbol *Result =
-      new (*this) MCSymbol(NameEntry.first->getKey(), isTemporary);
-
-  return Result;
+  llvm_unreachable("Infinite loop");
 }
 
-MCSymbol *MCContext::createTempSymbol(const Twine &Name) {
+MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix) {
   SmallString<128> NameSV;
   raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
-  return CreateSymbol(NameSV);
+  return CreateSymbol(NameSV, AlwaysAddSuffix);
 }
 
 MCSymbol *MCContext::CreateLinkerPrivateTempSymbol() {
   SmallString<128> NameSV;
-  raw_svector_ostream(NameSV)
-    << MAI->getLinkerPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
-  return CreateSymbol(NameSV);
+  raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp";
+  return CreateSymbol(NameSV, true);
 }
 
 MCSymbol *MCContext::CreateTempSymbol() {
-  SmallString<128> NameSV;
-  raw_svector_ostream(NameSV)
-    << MAI->getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
-  return CreateSymbol(NameSV);
+  return createTempSymbol("tmp", true);
 }
 
 unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
@@ -251,7 +250,7 @@ MCContext::getMachOSection(StringRef Segment, StringRef Section,
 
   MCSymbol *Begin = nullptr;
   if (BeginSymName)
-    Begin = createTempSymbol(BeginSymName);
+    Begin = createTempSymbol(BeginSymName, false);
 
   // Otherwise, return a new section.
   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
@@ -302,7 +301,7 @@ const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
 
   MCSymbol *Begin = nullptr;
   if (BeginSymName)
-    Begin = createTempSymbol(BeginSymName);
+    Begin = createTempSymbol(BeginSymName, false);
 
   MCSectionELF *Result = new (*this) MCSectionELF(
       CachedName, Type, Flags, Kind, EntrySize, GroupSym, Unique, Begin);
@@ -344,7 +343,7 @@ MCContext::getCOFFSection(StringRef Section, unsigned Characteristics,
 
   MCSymbol *Begin = nullptr;
   if (BeginSymName)
-    Begin = createTempSymbol(BeginSymName);
+    Begin = createTempSymbol(BeginSymName, false);
 
   StringRef CachedName = std::get<0>(Iter->first);
   MCSectionCOFF *Result = new (*this) MCSectionCOFF(