Kenneth Graunke
1ac1581f38
We've apparently always been botching JIP for sequences such as:
do
cmp.f0.0 ...
(+f0.0) break
...
if
...
else
...
endif
...
while
Normally, UIP is supposed to point to the final destination of the jump,
while in nested control flow, JIP is supposed to point to the end of the
current nesting level. It essentially bounces out of the current nested
control flow, to an instruction that has a JIP which bounces out another
level, and so on.
In the above example, when setting JIP for the BREAK, we call
brw_find_next_block_end(), which begins a search after the BREAK for the
next ENDIF, ELSE, WHILE, or HALT. It ignores the IF and finds the ELSE,
setting JIP there.
This makes no sense at all. The break is supposed to skip over the
whole if/else/endif block entirely. They have a sibling relationship,
not a nesting relationship.
This patch fixes brw_find_next_block_end() to track depth as it does
its search, and ignore anything not at depth 0. So when it sees the
IF, it ignores everything until after the ENDIF. That way, it finds
the end of the right block.
I noticed this while reading some assembly code. We believe jumping
earlier is harmless, but makes the EU walk through a bunch of disabled
instructions for no reason. I noticed that GLBenchmark Manhattan had
a shader that contained a BREAK with a bogus JIP, but didn't measure
any performance improvement (it's likely miniscule, if there is any).
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
File: docs/README.WIN32 Last updated: 21 June 2013 Quick Start ----- ----- Windows drivers are build with SCons. Makefiles or Visual Studio projects are no longer shipped or supported. Run scons libgl-gdi to build gallium based GDI driver. This will work both with MSVS or Mingw. Windows Drivers ------- ------- At this time, only the gallium GDI driver is known to work. Source code also exists in the tree for other drivers in src/mesa/drivers/windows, but the status of this code is unknown. Recipe ------ Building on windows requires several open-source packages. These are steps that work as of this writing. - install python 2.7 - install scons (latest) - install mingw, flex, and bison - install pywin32 from here: http://www.lfd.uci.edu/~gohlke/pythonlibs get pywin32-218.4.win-amd64-py2.7.exe - install git - download mesa from git see http://www.mesa3d.org/repository.html - run scons General ------- After building, you can copy the above DLL files to a place in your PATH such as $SystemRoot/SYSTEM32. If you don't like putting things in a system directory, place them in the same directory as the executable(s). Be careful about accidentially overwriting files of the same name in the SYSTEM32 directory. The DLL files are built so that the external entry points use the stdcall calling convention. Static LIB files are not built. The LIB files that are built with are the linker import files associated with the DLL files. The si-glu sources are used to build the GLU libs. This was done mainly to get the better tessellator code. If you have a Windows-related build problem or question, please post to the mesa-dev or mesa-users list.