I found an issue with the shader compiler for Cayman when I looked into why the ext_transform_feedback/order test case caused a GPU stall. It turned out the stall was an infinite loop that was the result of broken calculation in the shader function. The issue is that Cayman uses the tgsi_umad function for UMAD, but that does not work since it does not populate the y, z and w slots for UMUL that cayman requires.
This patch implements a cayman_umad. There are some things I'm unsure of though. The UMUL for Cayman is compiled to, as far as I can tell, ALU_OP2_MULLO_INT and not ALU_OP2_MULLO_UINT. So I do not know if I should use the int or the uint version in cayman_umad. In the patch I used the uint one, because that seemed the most logical. The add part of UMAD I copied from tgsi_umad and that had a loop around the variable lasti, but the variable lasti is usally not used in cayman specific code. This is used in tgsi functions. int lasti = tgsi_last_instruction(inst->Dst[0].Register.WriteMask); But in cayman specific code this is used instead. int last_slot = (inst->Dst[0].Register.WriteMask & 0x8) ? 4 : 3; It does not work to switch lasti with last_slot, since that makes the loop run too many times (in my test case lasti is 0 and last_slot is 3). So I just removed the loop, was that correct or should i resolve that in some other way? Martin Andersson (1): r600g: Add a Cayman specific version of UMAD src/gallium/drivers/r600/r600_shader.c | 47 +++++++++++++++++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-) -- 1.8.2 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
