[clang] Use StringRef::consume_front (NFC) (#139472)

Author: kazutakahirata

clang/lib/CodeGen/CGBlocks.cpp

@@ -40,8 +40,7 @@ CGBlockInfo::CGBlockInfo(const BlockDecl *block, StringRef name)
 
   // Skip asm prefix, if any.  'name' is usually taken directly from
   // the mangled name of the enclosing function.
-  if (!name.empty() && name[0] == '\01')
-    name = name.substr(1);
+  name.consume_front("\01");
 }
 
 // Anchor the vtable to this translation unit.

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -4500,8 +4500,7 @@ void CGDebugInfo::emitFunctionStart(GlobalDecl GD, SourceLocation Loc,
 
     Flags |= llvm::DINode::FlagPrototyped;
   }
-  if (Name.starts_with("\01"))
-    Name = Name.substr(1);
+  Name.consume_front("\01");
 
   assert((!D || !isa<VarDecl>(D) ||
           GD.getDynamicInitKind() != DynamicInitKind::NoStub) &&
@@ -4590,8 +4589,7 @@ void CGDebugInfo::EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
   } else {
     llvm_unreachable("not a function or ObjC method");
   }
-  if (!Name.empty() && Name[0] == '\01')
-    Name = Name.substr(1);
+  Name.consume_front("\01");
 
   if (D->isImplicit()) {
     Flags |= llvm::DINode::FlagArtificial;

clang/lib/CodeGen/CGExpr.cpp

@@ -3388,8 +3388,7 @@ LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
   auto SL = E->getFunctionName();
   assert(SL != nullptr && "No StringLiteral name in PredefinedExpr");
   StringRef FnName = CurFn->getName();
-  if (FnName.starts_with("\01"))
-    FnName = FnName.substr(1);
+  FnName.consume_front("\01");
   StringRef NameItems[] = {
       PredefinedExpr::getIdentKindName(E->getIdentKind()), FnName};
   std::string GVName = llvm::join(NameItems, NameItems + 2, ".");

clang/lib/CodeGen/CodeGenModule.cpp

@@ -4061,11 +4061,7 @@ namespace {
         return false;
       std::string BuiltinNameStr = BI.getName(BuiltinID);
       StringRef BuiltinName = BuiltinNameStr;
-      if (BuiltinName.starts_with("__builtin_") &&
-          Name == BuiltinName.slice(strlen("__builtin_"), StringRef::npos)) {
-        return true;
-      }
-      return false;
+      return BuiltinName.consume_front("__builtin_") && Name == BuiltinName;
     }
 
     bool VisitStmt(const Stmt *S) {