Fixed two issues in the type encoding parser:

- A correctness issue: with assertions disabled,
  ReadQuotedString would misbehave; and

- A performance issue: BuildType used a long
  chain of if()s; I changed that to two switch
  statements.  That also makes the code much
  nicer to step through when debugging it.

llvm-svn: 221651

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTypeEncodingParser.cpp

@@ -43,7 +43,8 @@ AppleObjCTypeEncodingParser::ReadQuotedString(lldb_utility::StringLexer& type)
     StreamString buffer;
     while (type.HasAtLeast(1) && type.Peek() != '"')
         buffer.Printf("%c",type.Next());
-    assert(type.Next() == '"');
+    StringLexer::Character next = type.Next();
+    assert (next == '"');
     return buffer.GetString();
 }
 
@@ -198,7 +199,7 @@ AppleObjCTypeEncodingParser::BuildObjCObjectPointerType (clang::ASTContext &ast_
             {
             default:
                 // roll back
-                type.PutBack(name.length() + 1);
+                type.PutBack(name.length() + 2); // undo our consumption of the string and of the quotes
                 name.clear();
                 break;
             case '}':
@@ -258,52 +259,67 @@ AppleObjCTypeEncodingParser::BuildType (clang::ASTContext &ast_ctx, StringLexer&
     if (!type.HasAtLeast(1))
         return clang::QualType();
     
-    if (type.NextIf('c'))
+    switch (type.Peek())
-        return ast_ctx.CharTy;
-    if (type.NextIf('i'))
-        return ast_ctx.IntTy;
-    if (type.NextIf('s'))
-        return ast_ctx.ShortTy;
-    if (type.NextIf('l'))
     {
-        ClangASTContext *lldb_ctx = ClangASTContext::GetASTContext(&ast_ctx);
+    default:
-        if (!lldb_ctx)
+        break;
-            return clang::QualType();
+    case '{':
-        return lldb_ctx->GetIntTypeFromBitSize(32, true).GetQualType();
+        return BuildStruct(ast_ctx, type, for_expression);
+    case '[':
+        return BuildArray(ast_ctx, type, for_expression);
+    case '(':
+        return BuildUnion(ast_ctx, type, for_expression);
+    case '@':
+        return BuildObjCObjectPointerType(ast_ctx, type, for_expression);
     }
-    if (type.NextIf('q'))
-        return ast_ctx.LongLongTy;
-    if (type.NextIf('C'))
-        return ast_ctx.UnsignedCharTy;
-    if (type.NextIf('I'))
-        return ast_ctx.UnsignedIntTy;
-    if (type.NextIf('S'))
-        return ast_ctx.UnsignedShortTy;
-    if (type.NextIf('L'))
-    {
-        ClangASTContext *lldb_ctx = ClangASTContext::GetASTContext(&ast_ctx);
-        if (!lldb_ctx)
-            return clang::QualType();
-        return lldb_ctx->GetIntTypeFromBitSize(32, false).GetQualType();
-    }
-    if (type.NextIf('Q'))
-        return ast_ctx.UnsignedLongLongTy;
-    if (type.NextIf('f'))
-        return ast_ctx.FloatTy;
-    if (type.NextIf('d'))
-        return ast_ctx.DoubleTy;
-    if (type.NextIf('B'))
-        return ast_ctx.BoolTy;
-    if (type.NextIf('v'))
-        return ast_ctx.VoidTy;
-    if (type.NextIf('*'))
-        return ast_ctx.getPointerType(ast_ctx.CharTy);
-    if (type.NextIf('#'))
-        return ast_ctx.getObjCClassType();
-    if (type.NextIf(':'))
-        return ast_ctx.getObjCSelType();
     
-    if (type.NextIf('b'))
+    switch (type.Next())
+    {
+    default:
+        type.PutBack(1);
+        return clang::QualType();
+    case 'c':
+        return ast_ctx.CharTy;
+    case 'i':
+        return ast_ctx.IntTy;
+    case 's':
+        return ast_ctx.ShortTy;
+    case 'l':
+        return ast_ctx.getIntTypeForBitwidth(32, true);
+        // this used to be done like this:
+        //   ClangASTContext *lldb_ctx = ClangASTContext::GetASTContext(&ast_ctx);
+        //   if (!lldb_ctx)
+        //      return clang::QualType();
+        //   return lldb_ctx->GetIntTypeFromBitSize(32, true).GetQualType();
+        // which uses one of the constants if one is available, but we don't think all this work is necessary.
+    case 'q':
+        return ast_ctx.LongLongTy;
+    case 'C':
+        return ast_ctx.UnsignedCharTy;
+    case 'I':
+        return ast_ctx.UnsignedIntTy;
+    case 'S':
+        return ast_ctx.UnsignedShortTy;
+    case 'L':
+        return ast_ctx.getIntTypeForBitwidth(32, false);
+        // see note for 'l'
+    case 'Q':
+        return ast_ctx.UnsignedLongLongTy;
+    case 'f':
+        return ast_ctx.FloatTy;
+    case 'd':
+        return ast_ctx.DoubleTy;
+    case 'B':
+        return ast_ctx.BoolTy;
+    case 'v':
+        return ast_ctx.VoidTy;
+    case '*':
+        return ast_ctx.getPointerType(ast_ctx.CharTy);
+    case '#':
+        return ast_ctx.getObjCClassType();
+    case ':':
+        return ast_ctx.getObjCSelType();
+    case 'b':
         {
             uint32_t size = ReadNumber(type);
             if (bitfield_bit_size)
@@ -314,8 +330,7 @@ AppleObjCTypeEncodingParser::BuildType (clang::ASTContext &ast_ctx, StringLexer&
             else
                 return clang::QualType();
         }
-    
+    case 'r':
-    if (type.NextIf('r'))
         {
             clang::QualType target_type = BuildType(ast_ctx, type, for_expression);
             if (target_type.isNull())
@@ -325,8 +340,7 @@ AppleObjCTypeEncodingParser::BuildType (clang::ASTContext &ast_ctx, StringLexer&
             else
                 return ast_ctx.getConstType(target_type);
         }
-    
+    case '^':
-    if (type.NextIf('^'))
         {
             if (!for_expression && type.NextIf('?'))
             {
@@ -347,23 +361,9 @@ AppleObjCTypeEncodingParser::BuildType (clang::ASTContext &ast_ctx, StringLexer&
                     return ast_ctx.getPointerType(target_type);
             }
         }
-    
+    case '?':
-    if (type.NextIf('?'))
         return for_expression ? ast_ctx.UnknownAnyTy : clang::QualType();
-    
+    }
-    if (type.Peek() == '{')
-        return BuildStruct(ast_ctx, type, for_expression);
-    
-    if (type.Peek() == '[')
-        return BuildArray(ast_ctx, type, for_expression);
-    
-    if (type.Peek() == '(')
-        return BuildUnion(ast_ctx, type, for_expression);
-    
-    if (type.Peek() == '@')
-        return BuildObjCObjectPointerType(ast_ctx, type, for_expression);
-    
-    return clang::QualType();
 }
 
 ClangASTType