<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Very slow reparsing for big header and even slower with preamble generation enabled"
href="https://llvm.org/bugs/show_bug.cgi?id=31353">31353</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Very slow reparsing for big header and even slower with preamble generation enabled
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>3.9
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows 2000
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>libclang
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>nikolai.kosjar@qt.io
</td>
</tr>
<tr>
<th>CC</th>
<td>klimek@google.com, llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=17748" name="attach_17748" title="libclangclient.cpp and testinput.cpp">attachment 17748</a> <a href="attachment.cgi?id=17748&action=edit" title="libclangclient.cpp and testinput.cpp">[details]</a></span>
libclangclient.cpp and testinput.cpp
Compile libclangclient.exe from the attached libclangclient.cpp.
Run libclangclient.exe with the attached testinput.cpp, which includes the
3.6MB windows header <Windows.UI.Xaml.Controls.h>.
The command line invocations here provide libclang with proper defines and
include paths from the MSVC2015 Update 3 toolchain, X86:
> set LIBCLANG_TIMING=1
> libclangclient.exe -m32 -target i686-pc-windows-msvc "-std=c++14"
-fms-extensions -fcxx-exceptions -fexceptions "-D__MSVCRT__=" "-D__w64="
"-D__int64=long long" "-D__int32=long" "-D__int16=short" "-D__int8=char"
"-D__ptr32=" "-D__ptr64=" "-D__COUNTER__=0" "-D_CPPRTTI=1" "-D_DEBUG=1"
"-D_DLL=1" "-D__FUNCDNAME__= __FUNCDNAME__ " "-D__FUNCSIG__= __FUNCSIG__ "
"-D__FUNCTION__= __FUNCTION__ " "-D_INTEGRAL_MAX_BITS=64" "-D_M_IX86=600"
"-D_M_IX86_FP=2" "-D_MSC_BUILD=0" "-D_MSC_EXTENSIONS=1"
"-D_MSC_FULL_VER=190024210" "-D_MSC_VER=1900" "-D_MT=1"
"-D_NATIVE_WCHAR_T_DEFINED=1" "-D_WCHAR_T_DEFINED=1" "-D_WIN32=1"
"-D__DATE__="\^""Dec 12 2016"\^""" "-D__TIME__="\^""12:20:52"\^"""
"-D__TIMESTAMP__="\^""Mon Dec 12 12:20:52 2016"\^""" "-DUNICODE=1" "-DWIN32=1"
"-DQT_NO_CAST_FROM_ASCII=1" "-D__WRL_NO_DEFAULT_LIB__=1"
"-DQT_WINRT_LIMITED_DRAGANDDROP=1" "-DQT_QML_DEBUG=1" "-DQT_NO_EXCEPTIONS=1"
"-DQT_PLUGIN=1" "-DQT_PLATFORMSUPPORT_LIB=1" "-DQT_GUI_LIB=1" "-DQT_CORE_LIB=1"
"-DQT_OPENGL_ES_2=1" "-DQT_OPENGL_ES_2_ANGLE=1" -U__cpp_aggregate_nsdmi
-U__cpp_alias_templates -U__cpp_attributes -U__cpp_binary_literals
-U__cpp_constexpr -U__cpp_decltype -U__cpp_decltype_auto
-U__cpp_delegating_constructors -U__cpp_digit_separators
-U__cpp_generic_lambdas -U__cpp_inheriting_constructors -U__cpp_init_captures
-U__cpp_initializer_lists -U__cpp_lambdas -U__cpp_nsdmi -U__cpp_range_based_for
-U__cpp_raw_strings -U__cpp_ref_qualifiers -U__cpp_return_type_deduction
-U__cpp_rtti -U__cpp_rvalue_references -U__cpp_static_assert
-U__cpp_unicode_characters -U__cpp_unicode_literals
-U__cpp_user_defined_literals -U__cpp_variable_templates
-U__cpp_variadic_templates -nostdinc -undef
-ID:\usr\qtcreator-4.2.0_689.exe\share\qtcreator\cplusplus\wrappedQtHeaders
-ID:\usr\qtcreator-4.2.0_689.exe\share\qtcreator\cplusplus\wrappedQtHeaders\QtCore
-ID:\dev\qt5\qtbase\src\plugins\platforms\winrt
-ID:\dev\qt5\qtbase\src\3rdparty\freetype\include -ID:\dev\qt5\qtbase\include
-ID:\dev\qt5\qtbase\include\QtPlatformSupport
-ID:\dev\qt5\qtbase\include\QtPlatformSupport\5.7.1
-ID:\dev\qt5\qtbase\include\QtPlatformSupport\5.7.1\QtPlatformSupport
-ID:\dev\qt5\qtbase\include\QtGui\5.7.1
-ID:\dev\qt5\qtbase\include\QtGui\5.7.1\QtGui -ID:\dev\qt5\qtbase\include\QtGui
-ID:\dev\qt5\qtbase\include\QtANGLE -ID:\dev\qt5\qtbase\include\QtCore\5.7.1
-ID:\dev\qt5\qtbase\include\QtCore\5.7.1\QtCore
-ID:\dev\qt5\qtbase\include\QtCore
-ID:\dev\qt5\qtbase\src\plugins\platforms\winrt\.moc\debug
-ID:\dev\qt5\qtbase\mkspecs\win32-msvc2015
-ID:\dev\qt5\qtbase\src\plugins\platforms\winrt\.uic "-IC:\Program Files
(x86)\Microsoft Visual Studio 14.0\VC\INCLUDE" "-IC:\Program Files
(x86)\Microsoft Visual Studio 14.0\VC\ATLMFC\INCLUDE" "-IC:\Program Files
(x86)\Windows Kits\10\include\10.0.10240.0\ucrt" "-IC:\Program Files
(x86)\Windows Kits\NETFXSDK\4.6.1\include\um" "-IC:\Program Files (x86)\Windows
Kits\8.1\include\\shared" "-IC:\Program Files (x86)\Windows
Kits\8.1\include\\um" "-IC:\Program Files (x86)\Windows
Kits\8.1\include\\winrt"
-IC:\Users\nik\AppData\Local\Temp\qtc-clang-uiheader-hk2hmc
"-fms-compatibility-version=19.00" "-fmessage-length=0"
-fdiagnostics-show-note-include-stack "-fmacro-backtrace-limit=0"
-fretain-comments-from-system-headers "-ferror-limit=1000" -x c++ -Weverything
-Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-unused-macros
-Wno-newline-eof -Wno-exit-time-destructors -Wno-global-constructors
-Wno-gnu-zero-variadic-macro-arguments -Wno-documentation -Wno-shadow
-Wno-missing-prototypes
D:\work\libclangclient.windows.slow_header\testinput.cpp
Parsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 7.3594
(100.0%) 0.1406 (100.0%) 7.5000 (100.0%) 7.5156 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 7.7500
(100.0%) 0.1563 (100.0%) 7.9063 (100.0%) 7.9532 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 7.4844
(100.0%) 0.1094 (100.0%) 7.5938 (100.0%) 7.6250 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 7.5781
(100.0%) 0.0781 (100.0%) 7.6563 (100.0%) 7.7187 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 7.5781
(100.0%) 0.1875 (100.0%) 7.7656 (100.0%) 7.8125 (100.0%)
Reparsing needs almost 8 seconds, which is already to much for IDE
requirements.
Change the line from
const unsigned options = /*CXTranslationUnit_PrecompiledPreamble*/ 0;
to
const unsigned options = CXTranslationUnit_PrecompiledPreamble;
then, recompile and rerun (same command line invocation, but now shortened):
> libclangclient.exe ...
D:\work\libclangclient.windows.slow_header\testinput.cpp
Parsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 7.5156
(100.0%) 0.1563 (100.0%) 7.6719 (100.0%) 7.7657 (100.0%)
Precompiling preamble: 10.0938 (100.0%) 0.2969 (100.0%) 10.3906 (100.0%)
10.6718 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 22.2031
(100.0%) 0.3281 (100.0%) 22.5313 (100.0%) 22.8801 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 12.1250
(100.0%) 0.0313 (100.0%) 12.1563 (100.0%) 12.2128 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 12.2031
(100.0%) 0.0469 (100.0%) 12.2500 (100.0%) 12.2813 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 12.2188
(100.0%) 0.0469 (100.0%) 12.2656 (100.0%) 12.2656 (100.0%)
Reparsing D:\work\libclangclient.windows.slow_header\testinput.cpp: 12.0938
(100.0%) 0.0625 (100.0%) 12.1563 (100.0%) 12.1875 (100.0%)
The preamble, which is supposed to speep up reparsing, makes things here even
slower - reparsing takes about 12s now.</pre>
</div>
</p>
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