diff options
Diffstat (limited to 'src/qml/doc/src/javascript/finetuning.qdoc')
| -rw-r--r-- | src/qml/doc/src/javascript/finetuning.qdoc | 63 |
1 files changed, 29 insertions, 34 deletions
diff --git a/src/qml/doc/src/javascript/finetuning.qdoc b/src/qml/doc/src/javascript/finetuning.qdoc index 97dc2421c5..0e8a913a2a 100644 --- a/src/qml/doc/src/javascript/finetuning.qdoc +++ b/src/qml/doc/src/javascript/finetuning.qdoc @@ -1,29 +1,5 @@ -/**************************************************************************** -** -** Copyright (C) 2019 The Qt Company Ltd. -** Contact: https://www.qt.io/licensing/ -** -** This file is part of the documentation of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:FDL$ -** Commercial License Usage -** Licensees holding valid commercial Qt licenses may use this file in -** accordance with the commercial license agreement provided with the -** Software or, alternatively, in accordance with the terms contained in -** a written agreement between you and The Qt Company. For licensing terms -** and conditions see https://www.qt.io/terms-conditions. For further -** information use the contact form at https://www.qt.io/contact-us. -** -** GNU Free Documentation License Usage -** Alternatively, this file may be used under the terms of the GNU Free -** Documentation License version 1.3 as published by the Free Software -** Foundation and appearing in the file included in the packaging of -** this file. Please review the following information to ensure -** the GNU Free Documentation License version 1.3 requirements -** will be met: https://www.gnu.org/licenses/fdl-1.3.html. -** $QT_END_LICENSE$ -** -****************************************************************************/ +// Copyright (C) 2019 The Qt Company Ltd. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only /*! \page qtqml-javascript-finetuning.html @@ -44,8 +20,11 @@ Running JavaScript code can be influenced by a few environment variables, partic considered for JIT compilation. The default value is 3 times. \row \li \c{QV4_FORCE_INTERPRETER} - \li Setting this environment variable disables the JIT and runs all - functions through the interpreter, no matter how often they are called. + \li Setting this environment variable runs all functions and expressions through the + interpreter. The JIT is never used, no matter how often a function or expression is + called. Functions and expressions may still be compiled ahead of time using + \l{qmlcachegen} or \l{qmlsc}, but only the generated byte code is used at run time. Any + generated C++ code and the machine code resulting from it is ignored. \row \li \c{QV4_JS_MAX_STACK_SIZE} \li The JavaScript engine reserves a special memory area as a stack to run JavaScript. @@ -82,9 +61,12 @@ Running JavaScript code can be influenced by a few environment variables, partic \li \c{QV4_MAX_CALL_DEPTH} \li Stack overflows when running (as opposed to compiling) JavaScript are prevented by controlling the call depth: the number of nested function invocations. By - default, an exception is generated if the call depth exceeds 1234. If it contains a - number, this environment variable overrides the maximum call depth. Beware that the - recursion limit when compiling JavaScript is not affected. + default, an exception is generated if the call depth exceeds a maximum number tuned + to the platform's default stack size. If the \c{QV4_MAX_CALL_DEPTH} environment + variable contains a number, this number is used as maximum call depth. Beware that + the recursion limit when compiling JavaScript is not affected. The default maximum + call depth is 1234 on most platforms. On QNX it is 640 because on QNX the default + stack size is smaller than on most platforms. \row \li \c{QV4_MM_AGGRESSIVE_GC} \li Setting this environment variable runs the garbage collector before each memory @@ -99,14 +81,27 @@ Running JavaScript code can be influenced by a few environment variables, partic \c{perf-<pid>.map} in \e{/tmp} which perf then reads. This environment variable, if set, causes the JIT to generate this file. \row - \li \c{QML_DISABLE_DISK_CACHE} - \li Disables the disk cache. See \l{The QML Disk Cache}. - \row \li \c{QV4_SHOW_BYTECODE} \li Outputs the IR bytecode generated by Qt to the console. Has to be combined with \c{QML_DISABLE_DISK_CACHE} or already cached bytecode will not be shown. + \row + \li \c{QV4_DUMP_BASIC_BLOCKS} + \li Outputs the basic blocks of each function compiled ahead of time. The details of the + blocks are printed to the console. Additionally, control flow graphs with the byte code + for each block are generated in the DOT format for each compiled function. The value of + \c {QV4_DUMP_BASIC_BLOCKS} is used as the path to the folder where the DOT files should + be generated. If the path is any of ["-", "1", "true"] or if files can't be opened, + the graphs are dumped to stdout instead. + \row + \li \c{QV4_VALIDATE_BASIC_BLOCKS} + \li Performs checks on the basic blocks of a function compiled ahead of time to validate + its structure and coherence. If the validation fails, an error message is printed to + the console. \endtable +\l{The QML Disk Cache} accepts further environment variables that allow fine tuning its behavior. +In particular \c{QML_DISABLE_DISK_CACHE} may be useful for debugging. + */ |