[SchedModel] Avoid std::string creation for instregex patterns that don't contain regex metas. NFCI.

llvm-svn: 328436

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/utils/TableGen/CodeGenSchedule.cpp b/llvm/utils/TableGen/CodeGenSchedule.cpp
index 1b516c17530..b73e0767e3b 100644
--- a/llvm/utils/TableGen/CodeGenSchedule.cpp
+++ b/llvm/utils/TableGen/CodeGenSchedule.cpp
@@ -95,9 +95,10 @@ struct InstRegexOp : public SetTheory::Operator {
 
       Optional<Regex> Regexpr = None;
       StringRef Prefix = Original.substr(0, FirstMeta);
-      std::string pat = Original.substr(FirstMeta);
-      if (!pat.empty()) {
+      StringRef PatStr = Original.substr(FirstMeta);
+      if (!PatStr.empty()) {
         // For the rest use a python-style prefix match.
+        std::string pat = PatStr;
         if (pat[0] != '^') {
           pat.insert(0, "^(");
           pat.insert(pat.end(), ')');