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: 238601

clang/lib/CodeGen/CodeGenModule.cpp

@@ -921,13 +921,13 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
 void CodeGenModule::addUsedGlobal(llvm::GlobalValue *GV) {
   assert(!GV->isDeclaration() &&
          "Only globals with definition can force usage.");
-  LLVMUsed.push_back(GV);
+  LLVMUsed.emplace_back(GV);
 }
 
 void CodeGenModule::addCompilerUsedGlobal(llvm::GlobalValue *GV) {
   assert(!GV->isDeclaration() &&
          "Only globals with definition can force usage.");
-  LLVMCompilerUsed.push_back(GV);
+  LLVMCompilerUsed.emplace_back(GV);
 }
 
 static void emitUsed(CodeGenModule &CGM, StringRef Name,