Consider the following code sequence:
mul(8) g4<1>F g1<0,4,1>.wzwwF g3<4,4,1>.wzwwF
mov.sat(8) m1<1>.xyF g4<4,4,1>F
mul(8) g4<1>F g1<0,4,1>.xxyxF g3<4,4,1>.xxyxF
mov.sat(8) m1<1>.zwF g4<4,4,1>F
The compute-to-MRF pass will discover the first mov.sat and attempt to
replace it by rewriting earlier instructions. Everything works out,
so it replaces scan_inst's destination file, reg, and reg_offset,
resulting in:
mul(8) m1<1>F g1<0,4,1>.wzwwF g3<4,4,1>.wzwwF
mul(8) g4<1>F g1<0,4,1>.xxyxF g3<4,4,1>.xxyxF
mov.sat(8) m1<1>.zwF g4<4,4,1>F
Unfortunately, it loses the .xy writemask on the mov.sat's MRF
destination. While this doesn't pose an immediate problem, it then
proceeds to transform the second mov.sat, resulting in:
mul(8) m1<1>F g1<0,4,1>.wzwwF g3<4,4,1>.wzwwF
mul(8) m1<1>F g1<0,4,1>.xxyxF g3<4,4,1>.xxyxF
Instead of writing both halves of the vector (like the original code),
it overwrites the full vector both times, clobbering the desired .xy
values.
When encountering a MOV, the compute-to-MRF code scans for instructions
which generate channels of the MOV source. It ensures that all
necessary channels are available (possibly written by several
instructions). In this case, *more* channels are available than
necessary, so we want to take the subset that's actually used.
Taking the bitwise and of both writemasks should accomplish that.
This was discovered by analyzing an ARB_vertex_program test
(glean/vertProg1/MUL test (with swizzle and masking)) with my new
Mesa IR -> Vec4 IR translator code. However, it should be possible
with GLSL programs as well.
NOTE: This is a candidate for stable release branches.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
File: docs/README.WIN32
Last updated: 23 April 2011
Quick Start
----- -----
Windows drivers are build with SCons. Makefiles or Visual Studio projects are
no longer shipped or supported.
Run
scons osmesa mesagdi
to build classic mesa Windows GDI drivers; or
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.
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.
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