When register allocation on an IR in SSA form is done, the last step is
to turn the Phi nodes into moves and swaps and put those instructions in
the predecessors. As the Phi nodes are conceptually "executed in
parallel", this can result in cycles:
r1 <- r0
r0 <- r1
These have to be turned into a swap instruction. Also, the moves have to
be ordered in order to make sure that no values are overwritten:
r1 <- r0
r2 <- r1
Here the two moves need to be switched. The comments in the code
document the algorithm.
Change-Id: I4151988681f7554b00a3eb70d224e6e2f29ebf04
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
From Qt 5.7 -> tools & applications are lisenced under GPL v3 with some
exceptions, see
http://blog.qt.io/blog/2016/01/13/new-agreement-with-the-kde-free-qt-foundation/
Updated license headers to use new GPL-EXCEPT header instead of LGPL21 one
(in those files which will be under GPL 3 with exceptions)
Change-Id: I04760a0801837cfc516d1c7c02d4f503f6bb70b6
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
The keyword no longer has a meaning for the new CI.
Change-Id: I699f2881e291cce02a6a608a8710638886e38daa
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>
Qt copyrights are now in The Qt Company, so we could update the source
code headers accordingly. In the same go we should also fix the links to
point to qt.io.
Change-Id: I61120571787870c0ed17066afb31779b1e6e30e9
Reviewed-by: Iikka Eklund <iikka.eklund@theqtcompany.com>
There are two changes in this patch, that go hand-in-hand. First, when
re-numbering the statements in order of occurrence in the scheduled
basic-blocks, the (new) position is not stored in the statement itself,
but in the LifeTimeIntervals class. This makes it possible to re-use
information gathered during SSA formation or optimization.
The re-numbering itself has also changed, resulting in some minor
changes to the life-time interval calculation. The new numbering
is described in LifeTimeIntervals::renumber(). The reason is to make it
easy for the register allocator and stack-slot allocator to distinguish
between definition of a temporary and its uses. Example:
20: %3 = %2 + %1
22: print(%3)
If the life-time of %2 or %1 ends at 20, then at the point that %3 gets
assigned, it can re-use the storage occupied by %1 or %2. Also, when
both %1 and %2 need to get a register assigned (because they were
spilled to the stack, for example), %3 should be allocated "after" both
%1 and %2. So, instead of having a closed interval of [20-22] for %3, we
want to use an open interval of (20-22]. To simulate the "open" part, the
life-time of %3 is set to [21-22]. So, all statements live on even
positions, and temporaries defined by a statement start at
statmentPosition + 1.
Change-Id: I0eda2c653b0edf1a529bd0762d338b0ea9a66aa0
Sanity-Review: Qt Sanity Bot <qt_sanitybot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Also added some "white-box" unit tests and sprinkled in a bit of
documentation. The case that went wrong is covered by the test
rangeSplitting_1: before the fix, the new interval would have
two ranges: [66-64],[70-71]. The first range is invalid and should not
be there at all.
Change-Id: If0742f4e6a96d98ea5d696f95126886ba66f92bb
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Thiago Macieira
Erik Verbruggen
Jani Heikkinen
Friedemann Kleint
Jani Heikkinen
Erik Verbruggen
Lars Knoll