We can not use the VUE Dereference flags combination for EOT message under ILK and SNB because the threads are not initialized there with initial VUE handle unlike Pre-IL. So to avoid GPU hangs on SNB and ILK we need to avoid usage of the VUE Dereference flags combination. (Was tested only on SNB but according to the specification SNB Volume 2 Part 1: 1.6.5.3, 1.6.5.6 the ILK must behave itself in the similar way)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105399 Signed-off-by: Andrii Simiklit <andrii.simik...@globallogic.com> --- src/intel/compiler/gen6_gs_visitor.cpp | 56 +++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 7 deletions(-) diff --git a/src/intel/compiler/gen6_gs_visitor.cpp b/src/intel/compiler/gen6_gs_visitor.cpp index 66c69fb..ac3ba55 100644 --- a/src/intel/compiler/gen6_gs_visitor.cpp +++ b/src/intel/compiler/gen6_gs_visitor.cpp @@ -300,10 +300,11 @@ gen6_gs_visitor::emit_urb_write_opcode(bool complete, int base_mrf, /* Otherwise we always request to allocate a new VUE handle. If this is * the last write before the EOT message and the new handle never gets * used it will be dereferenced when we send the EOT message. This is - * necessary to avoid different setups for the EOT message (one for the + * necessary to avoid different setups (under Pre-IL only) for the EOT message (one for the * case when there is no output and another for the case when there is) * which would require to end the program with an IF/ELSE/ENDIF block, - * something we do not want. + * something we do not want. + * But for ILK and SNB we can not avoid the end the program with an IF/ELSE/ENDIF block. */ inst = emit(GS_OPCODE_URB_WRITE_ALLOCATE); inst->urb_write_flags = BRW_URB_WRITE_COMPLETE; @@ -449,8 +450,11 @@ gen6_gs_visitor::emit_thread_end() if (prog->info.has_transform_feedback_varyings) xfb_write(); } - emit(BRW_OPCODE_ENDIF); - + const bool common_eot_approach_can_be_used = (devinfo->gen < 5); + if(common_eot_approach_can_be_used) + { + emit(BRW_OPCODE_ENDIF); + } /* Finally, emit EOT message. * * In gen6 we need to end the thread differently depending on whether we have @@ -463,8 +467,32 @@ gen6_gs_visitor::emit_thread_end() * VUE handle every time we do a URB WRITE, even for the last vertex we emit. * With this we make sure that whether we have emitted at least one vertex * or none at all, we have to finish the thread without writing to the URB, - * which works for both cases by setting the COMPLETE and UNUSED flags in - * the EOT message. + * which works for both cases (but only under Pre-IL) by setting + * the COMPLETE and UNUSED flags in the EOT message. + * + * But under ILK or SNB we must not use combination COMPLETE and UNUSED + * because this combination could be used only for already allocated VUE. + * But unlike Pre-IL in the ILK and SNB + * the initial VUE is not passed to threads. + * This behaver mentioned in specification: + * SNB Volume 2 Part 1: + * "1.6.5.3 VUE Allocation (GS, CLIP) [DevIL]" + * "1.6.5.4 VUE Allocation (GS) [DevSNB+]" + * "The threads are not passed an initial handle. + * Instead, they request a first handle (if any) + * via the URB shared function’s FF_SYNC message (see Shared Functions). + * If additional handles are required, + * the URB_WRITE allocate mechanism (mentioned above) is used." + * + * So for ILK and for SNB we must use only UNUSED flag. + * This is accepteble combination according to: + * SNB Volume 4 Part 2: + * "2.4.2 Message Descriptor" + * "Table lists the valid and invalid combinations of + * the Complete, Used, Allocate and EOT bits" + * "Thread terminate non-write of URB" + * SNB Volume 2 Part 1: + * "1.6.5.6 Thread Termination" */ this->current_annotation = "gen6 thread end: EOT"; @@ -480,8 +508,22 @@ gen6_gs_visitor::emit_thread_end() inst->urb_write_flags = BRW_URB_WRITE_COMPLETE | BRW_URB_WRITE_UNUSED; inst->base_mrf = base_mrf; inst->mlen = 1; -} + + if(!common_eot_approach_can_be_used) + { + emit(BRW_OPCODE_ELSE); + + this->current_annotation = "gen6 thread end: EOT"; + + vec4_instruction *unused_urb_inst = emit(GS_OPCODE_THREAD_END); + unused_urb_inst->urb_write_flags = BRW_URB_WRITE_UNUSED; + unused_urb_inst->base_mrf = base_mrf; + unused_urb_inst->mlen = 1; + emit(BRW_OPCODE_ENDIF); + } +} + void gen6_gs_visitor::setup_payload() { -- 2.7.4 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
