diff options
authorIago Toral Quiroga <>2015-07-20 12:58:12 +0200
committerIago Toral Quiroga <>2015-07-21 09:00:14 +0200
commitb298311d517017834841e53b7e641738e6067cdc (patch)
parent2f11e92cef51c88a09bc778e2ceca4ab50cf0017 (diff)
i965/vec4: Fix liveness analysis with BRW_OPCODE_SEL
We only consider a vgrf defined by a given block if the block writes to it unconditionally. So far we have been checking this by testing that the instruction is not predicated, however, in the case of BRW_OPCODE_SEL, the predication is used to select the value to write, not to decide if the write is actually done. The consequence of this was increased life spans for affected vgrfs, which could lead to additional register pressure. Since NIR generates selects for conditional writes this was causing massive register pressure in a handful of piglit and dEQP tests that had a large number of select operations with the NIR-vec4 backend. Fixes the following piglit tests with the NIR-vec4 backend: spec/glsl-1.50/execution/variable-indexing/vs-output-array-vec4-index-wr-before-gs spec/glsl-1.50/execution/variable-indexing/gs-input-array-vec4-index-rd spec/glsl-1.50/execution/variable-indexing/vs-output-array-vec2-index-wr-before-gs spec/glsl-1.50/execution/variable-indexing/vs-output-array-vec3-index-wr-before-gs spec/glsl-1.50/execution/variable-indexing/vs-output-array-float-index-wr-before-gs Fixes 80 dEQP tests with the NIR-vec4 backend in the following category: dEQP-GLES3.functional.ubo.* Reviewed-by: Francisco Jerez <> Reviewed-by: Kenneth Graunke <>
1 files changed, 2 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
index 29b4a53418a..cc688ef8083 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_live_variables.cpp
@@ -96,7 +96,8 @@ vec4_live_variables::setup_def_use()
* are the things that screen off preceding definitions of a
* variable, and thus qualify for being in def[].
- if (inst->dst.file == GRF && !inst->predicate) {
+ if (inst->dst.file == GRF &&
+ (!inst->predicate || inst->opcode == BRW_OPCODE_SEL)) {
for (unsigned i = 0; i < inst->regs_written; i++) {
for (int c = 0; c < 4; c++) {
if (inst->dst.writemask & (1 << c)) {