Rename temporary symbols if they conflict with artificial symbols created

by the assembler. This was blocking parsing any large .s produced by clang for
example.

Fixes PR8596.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120603 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -45,6 +45,10 @@ namespace llvm {
     /// Symbols - Bindings of names to symbols.
     StringMap<MCSymbol*> Symbols;
 
+    /// UsedNames - Keeps tracks of names that were used both for used declared
+    /// and artificial symbols.
+    StringMap<bool> UsedNames;
+
     /// NextUniqueID - The next ID to dole out to an unnamed assembler temporary
     /// symbol.
     unsigned NextUniqueID;
@@ -91,6 +95,9 @@ namespace llvm {
     BumpPtrAllocator Allocator;
 
     void *MachOUniquingMap, *ELFUniquingMap, *COFFUniquingMap;
+
+    MCSymbol *CreateSymbol(StringRef Name);
+
   public:
     explicit MCContext(const MCAsmInfo &MAI);
     ~MCContext();

lib/MC/MCContext.cpp

@@ -57,19 +57,41 @@ MCContext::~MCContext() {
 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
 
-  // Determine whether this is an assembler temporary or normal label.
-  bool isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
-
   // Do the lookup and get the entire StringMapEntry.  We want access to the
   // key if we are creating the entry.
   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
-  if (Entry.getValue()) return Entry.getValue();
+  MCSymbol *Sym = Entry.getValue();
+
+  if (Sym)
+    return Sym;
+
+  Sym = CreateSymbol(Name);
+  Entry.setValue(Sym);
+  return Sym;
+}
+
+MCSymbol *MCContext::CreateSymbol(StringRef Name) {
+  // Determine whether this is an assembler temporary or normal label.
+  bool isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
+
+  StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
+  if (NameEntry->getValue()) {
+    assert(isTemporary && "Cannot rename non temporary symbols");
+    SmallString<128> NewName;
+    do {
+      Twine T = Name + Twine(NextUniqueID++);
+      T.toVector(NewName);
+      StringRef foo = NewName;
+      NameEntry = &UsedNames.GetOrCreateValue(foo);
+    } while (NameEntry->getValue());
+  }
+  NameEntry->setValue(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 StringMapEntry.
-  MCSymbol *Result = new (*this) MCSymbol(Entry.getKey(), isTemporary);
-  Entry.setValue(Result);
-  return Result; 
+  // to the copy of the string that is embedded in the UsedNames entry.
+  MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
+
+  return Result;
 }
 
 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
@@ -79,8 +101,11 @@ MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
 }
 
 MCSymbol *MCContext::CreateTempSymbol() {
-  return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
-                           "tmp" + Twine(NextUniqueID++));
+  SmallString<128> NameSV;
+  Twine Name = Twine(MAI.getPrivateGlobalPrefix()) + "tmp" +
+    Twine(NextUniqueID++);
+  Name.toVector(NameSV);
+  return CreateSymbol(NameSV);
 }
 
 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {

test/MC/AsmParser/rename.s

@@ -0,0 +1,10 @@
+// RUN: llvm-mc -triple i386-unknown-unknown %s | FileCheck %s
+
+        .size bar, . - bar
+.Ltmp0:
+       .size foo, .Ltmp0 - foo
+
+// CHECK: .Ltmp0:
+// CHECK: .size  bar, .Ltmp0-bar
+// CHECK: .Ltmp01
+// CHECK: .size foo, .Ltmp01-foo