29bc68cf16
Most processors have carry flags which they set on addition overflow, so it's a good idea to access them whenever possible. Most of them also have widening multiply instructions that can be used to detect overflow of the non-widening version. Tested to compile on: Architecture Compiler x86 GCC 4.9, GCC 5*, Clang 3.6*, ICC 16 beta x86-64 GCC 4.9, GCC 5*, Clang 3.6*, ICC 16 beta x86-64 ILP32 GCC 4.9, GCC 5*, Clang 3.6* IA-64 LP64 GCC 4.8 ARMv7-A GCC 4.9, Clang 3.6* AArch64 Clang 3.6* MIPS GCC 4.9, Clang 3.6* MIPS64 GCC 4.9, Clang 3.6* PowerPC GCC 4.9, Clang 3.6* PowerPC 64 GCC 4.9, Clang 3.6* SPARC Clang 3.6* SPARCv9 Clang 3.6* [*] supports the intrinsics If the compiler does not offer a way to detect an overflow, we do it by hand. For unsigned additions, that's easy, since the C++ language specifies the behavior of the overflow. That's also the reason why this code is implemented only for unsigned integers. For the multiplication, if the compiler does not support widening multiplications, we do it with a division instead. This is necessary for GCC < 4.5 and compilers not compatible with GCC or MSVC. Change-Id: I049a653beeb5454c9539ffff13e637de0f1338c1 Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com> Reviewed-by: Alex Trotsenko <alex1973tr@gmail.com> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com> |
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| .. | ||
| auto | ||
| baselineserver | ||
| benchmarks | ||
| global | ||
| manual | ||
| shared | ||
| README | ||
| tests.pro | ||
This directory contains autotests and benchmarks based on Qt Test. In order
to run the autotests reliably, you need to configure a desktop to match the
test environment that these tests are written for.
Linux X11:
* The user must be logged in to an active desktop; you can't run the
autotests without a valid DISPLAY that allows X11 connections.
* The tests are run against a KDE3 or KDE4 desktop.
* Window manager uses "click to focus", and not "focus follows mouse". Many
tests move the mouse cursor around and expect this to not affect focus
and activation.
* Disable "click to activate", i.e., when a window is opened, the window
manager should automatically activate it (give it input focus) and not
wait for the user to click the window.