Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial types

If the type isn't trivially moveable emplace can skip a potentially
expensive move. It also saves a couple of characters.


Call sites were found with the ASTMatcher + some semi-automated cleanup.

memberCallExpr(
    argumentCountIs(1), callee(methodDecl(hasName("push_back"))),
    on(hasType(recordDecl(has(namedDecl(hasName("emplace_back")))))),
    hasArgument(0, bindTemporaryExpr(
                       hasType(recordDecl(hasNonTrivialDestructor())),
                       has(constructExpr()))),
    unless(isInTemplateInstantiation()))

No functional change intended.

llvm-svn: 238602
diff --git a/llvm/lib/TableGen/TGParser.cpp b/llvm/lib/TableGen/TGParser.cpp
index ed01970..66d85556 100644
--- a/llvm/lib/TableGen/TGParser.cpp
+++ b/llvm/lib/TableGen/TGParser.cpp
@@ -1601,7 +1601,7 @@
     // DagArg ::= VARNAME
     if (Lex.getCode() == tgtok::VarName) {
       // A missing value is treated like '?'.
-      Result.push_back(std::make_pair(UnsetInit::get(), Lex.getCurStrVal()));
+      Result.emplace_back(UnsetInit::get(), Lex.getCurStrVal());
       Lex.Lex();
     } else {
       // DagArg ::= Value (':' VARNAME)?
@@ -2174,7 +2174,7 @@
     if (!Val) return std::vector<LetRecord>();
 
     // Now that we have everything, add the record.
-    Result.push_back(LetRecord(Name, Bits, Val, NameLoc));
+    Result.emplace_back(std::move(Name), std::move(Bits), Val, NameLoc);
 
     if (Lex.getCode() != tgtok::comma)
       return Result;