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/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index cc2fbbd..baab387 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -352,7 +352,7 @@
   if (!TUs.empty())
     return;
   for (const auto &I : getTypesSections()) {
-    TUs.push_back(DWARFUnitSection<DWARFTypeUnit>());
+    TUs.emplace_back();
     TUs.back().parse(*this, I.second);
   }
 }
@@ -365,7 +365,7 @@
   if (!DWOTUs.empty())
     return;
   for (const auto &I : getTypesDWOSections()) {
-    DWOTUs.push_back(DWARFUnitSection<DWARFTypeUnit>());
+    DWOTUs.emplace_back();
     DWOTUs.back().parseDWO(*this, I.second);
   }
 }