Use printable names to implement directional labels.

This changes the implementation of local directional labels to use a dedicated
map. With that it can then just use CreateTempSymbol, which is what the rest
of MC uses.

CreateTempSymbol doesn't do a great job at making sure the names are unique
(or being efficient when the names are not needed), but that should probably
be fixed in a followup patch.

This fixes pr18928.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203826 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -70,6 +70,14 @@ namespace llvm {
     /// Symbols - Bindings of names to symbols.
     SymbolTable Symbols;
 
+    /// A maping from a local label number and an instance count to a symbol.
+    /// For example, in the assembly
+    ///     1:
+    ///     2:
+    ///     1:
+    /// We have three labels represented by the pairs (1, 0), (2, 0) and (1, 1)
+    DenseMap<std::pair<unsigned, unsigned>, MCSymbol*> LocalSymbols;
+
     /// UsedNames - Keeps tracks of names that were used both for used declared
     /// and artificial symbols.
     StringMap<bool, BumpPtrAllocator&> UsedNames;
@@ -82,10 +90,10 @@ namespace llvm {
     DenseMap<unsigned, MCLabel *> Instances;
     /// NextInstance() creates the next instance of the directional local label
     /// for the LocalLabelVal and adds it to the map if needed.
-    unsigned NextInstance(int64_t LocalLabelVal);
+    unsigned NextInstance(unsigned LocalLabelVal);
     /// GetInstance() gets the current instance of the directional local label
     /// for the LocalLabelVal and adds it to the map if needed.
-    unsigned GetInstance(int64_t LocalLabelVal);
+    unsigned GetInstance(unsigned LocalLabelVal);
 
     /// The file name of the log file from the environment variable
     /// AS_SECURE_LOG_FILE.  Which must be set before the .secure_log_unique
@@ -154,6 +162,9 @@ namespace llvm {
 
     MCSymbol *CreateSymbol(StringRef Name);
 
+    MCSymbol *getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
+                                                unsigned Instance);
+
   public:
     explicit MCContext(const MCAsmInfo *MAI, const MCRegisterInfo *MRI,
                        const MCObjectFileInfo *MOFI, const SourceMgr *Mgr = 0,
@@ -190,13 +201,13 @@ namespace llvm {
     /// symbol names.
     unsigned getUniqueSymbolID() { return NextUniqueID++; }
 
-    /// CreateDirectionalLocalSymbol - Create the definition of a directional
-    /// local symbol for numbered label (used for "1:" definitions).
-    MCSymbol *CreateDirectionalLocalSymbol(int64_t LocalLabelVal);
+    /// Create the definition of a directional local symbol for numbered label
+    /// (used for "1:" definitions).
+    MCSymbol *CreateDirectionalLocalSymbol(unsigned LocalLabelVal);
 
-    /// GetDirectionalLocalSymbol - Create and return a directional local
-    /// symbol for numbered label (used for "1b" or 1f" references).
-    MCSymbol *GetDirectionalLocalSymbol(int64_t LocalLabelVal, int bORf);
+    /// Create and return a directional local symbol for numbered label (used
+    /// for "1b" or 1f" references).
+    MCSymbol *GetDirectionalLocalSymbol(unsigned LocalLabelVal, bool Before);
 
     /// GetOrCreateSymbol - Lookup the symbol inside with the specified
     /// @p Name.  If it exists, return it.  If not, create a forward

lib/MC/MCContext.cpp

@@ -162,32 +162,39 @@ MCSymbol *MCContext::CreateTempSymbol() {
   return CreateSymbol(NameSV);
 }
 
-unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
+unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
   MCLabel *&Label = Instances[LocalLabelVal];
   if (!Label)
     Label = new (*this) MCLabel(0);
   return Label->incInstance();
 }
 
-unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
+unsigned MCContext::GetInstance(unsigned LocalLabelVal) {
   MCLabel *&Label = Instances[LocalLabelVal];
   if (!Label)
     Label = new (*this) MCLabel(0);
   return Label->getInstance();
 }
 
-MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
-  return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
-                           Twine(LocalLabelVal) +
-                           "\2" +
-                           Twine(NextInstance(LocalLabelVal)));
+MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
+                                                       unsigned Instance) {
+  MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
+  if (!Sym)
+    Sym = CreateTempSymbol();
+  return Sym;
 }
-MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
-                                               int bORf) {
-  return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
-                           Twine(LocalLabelVal) +
-                           "\2" +
-                           Twine(GetInstance(LocalLabelVal) + bORf));
+
+MCSymbol *MCContext::CreateDirectionalLocalSymbol(unsigned LocalLabelVal) {
+  unsigned Instance = NextInstance(LocalLabelVal);
+  return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
+}
+
+MCSymbol *MCContext::GetDirectionalLocalSymbol(unsigned LocalLabelVal,
+                                               bool Before) {
+  unsigned Instance = GetInstance(LocalLabelVal);
+  if (!Before)
+    ++Instance;
+  return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
 }
 
 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {

lib/MC/MCParser/AsmParser.cpp

@@ -884,7 +884,7 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
       }
       if (IDVal == "f" || IDVal == "b") {
         MCSymbol *Sym =
-            Ctx.GetDirectionalLocalSymbol(IntVal, IDVal == "f" ? 1 : 0);
+            Ctx.GetDirectionalLocalSymbol(IntVal, IDVal == "b");
         Res = MCSymbolRefExpr::Create(Sym, Variant, getContext());
         if (IDVal == "b" && Sym->isUndefined())
           return Error(Loc, "invalid reference to undefined symbol");

lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -1105,8 +1105,7 @@ bool X86AsmParser::ParseIntelExpression(IntelExprStateMachine &SM, SMLoc &End) {
         StringRef IDVal = getTok().getString();
         if (IDVal == "f" || IDVal == "b") {
           MCSymbol *Sym =
-            getContext().GetDirectionalLocalSymbol(IntVal,
-                                                   IDVal == "f" ? 1 : 0);
+              getContext().GetDirectionalLocalSymbol(IntVal, IDVal == "b");
           MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
           const MCExpr *Val = 
 	    MCSymbolRefExpr::Create(Sym, Variant, getContext());

test/MC/X86/intel-syntax-directional-label.s

@@ -8,9 +8,10 @@ FUNCTION_NAME:
 	.intel_syntax
 	cmp rdi, 1
 	jge 1f
-// CHECK:	jge	"L11"
+// CHECK:	jge	Ltmp0
 	add rdi, 2
+// CHECK: addq $2, %rdi
 1:
-// CHECK:	"L11":
+// CHECK:	Ltmp0:
 	add rdi, 1
 	ret