<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">I’m not familiar with those performance issues, so I’m CC’ing Howard in case he can provide any details on those issues. In general, we’re in the process of migrating away from libstdc++ on OS X and iOS, so we really do want the default to be libc++ regardless of the language mode. If you have particularly performance sensitive code, you can always choose to use libstdc++.<div><br><div><div><div>On Nov 2, 2013, at 7:05 PM, Nico Weber <<a href="mailto:thakis@chromium.org">thakis@chromium.org</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">Thanks for upstreaming this!<div><br></div><div>Should this only happen in C++11 mode? libc++ seems to be measurably slower than libstdc++ in C++03 mode (PR17703, PR14554, PR14555).</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Sat, Nov 2, 2013 at 4:19 PM, Bob Wilson <span dir="ltr"><<a href="mailto:bob.wilson@apple.com" target="_blank">bob.wilson@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Author: bwilson<br>
Date: Sat Nov 2 18:19:53 2013<br>
New Revision: 193934<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=193934&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=193934&view=rev</a><br>
Log:<br>
Default to use libc++ on OS X 10.9+ and iOS 7+.<br>
<br>
Modified:<br>
cfe/trunk/lib/Driver/ToolChains.cpp<br>
cfe/trunk/test/PCH/cxx-typeid.cpp<br>
<br>
Modified: cfe/trunk/lib/Driver/ToolChains.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.cpp?rev=193934&r1=193933&r2=193934&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.cpp?rev=193934&r1=193933&r2=193934&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/lib/Driver/ToolChains.cpp (original)<br>
+++ cfe/trunk/lib/Driver/ToolChains.cpp Sat Nov 2 18:19:53 2013<br>
@@ -839,6 +839,12 @@ DerivedArgList *Darwin::TranslateArgs(co<br>
}<br>
}<br>
<br>
+ // Default to use libc++ on OS X 10.9+ and iOS 7+.<br>
+ if (((isTargetMacOS() && !isMacosxVersionLT(10, 9)) ||<br>
+ (isTargetIPhoneOS() && !isIPhoneOSVersionLT(7, 0))) &&<br>
+ !Args.getLastArg(options::OPT_stdlib_EQ))<br>
+ DAL->AddJoinedArg(0, Opts.getOption(options::OPT_stdlib_EQ), "libc++");<br>
+<br>
// Validate the C++ standard library choice.<br>
CXXStdlibType Type = GetCXXStdlibType(*DAL);<br>
if (Type == ToolChain::CST_Libcxx) {<br>
<br>
Modified: cfe/trunk/test/PCH/cxx-typeid.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx-typeid.cpp?rev=193934&r1=193933&r2=193934&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx-typeid.cpp?rev=193934&r1=193933&r2=193934&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/test/PCH/cxx-typeid.cpp (original)<br>
+++ cfe/trunk/test/PCH/cxx-typeid.cpp Sat Nov 2 18:19:53 2013<br>
@@ -1,8 +1,8 @@<br>
// Test this without pch.<br>
-// RUN: %clang_cc1 -include %S/cxx-typeid.h -fsyntax-only -verify %s<br>
+// RUN: %clang_cc1 -include %S/cxx-typeid.h -fsyntax-only -stdlib=libstdc++ -verify %s<br>
<br>
-// RUN: %clang_cc1 -x c++-header -emit-pch -o %t.pch %S/cxx-typeid.h<br>
-// RUN: %clang_cc1 -include-pch %t.pch -fsyntax-only -verify %s<br>
+// RUN: %clang_cc1 -x c++-header -emit-pch -stdlib=libstdc++ -o %t.pch %S/cxx-typeid.h<br>
+// RUN: %clang_cc1 -include-pch %t.pch -fsyntax-only -stdlib=libstdc++ -verify %s<br>
<br>
// expected-no-diagnostics<br>
<br>
<br>
<br>
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