diff options
| author | Matt Turner <[email protected]> | 2013-09-19 19:31:31 -0700 |
|---|---|---|
| committer | Matt Turner <[email protected]> | 2013-10-07 10:41:17 -0700 |
| commit | 92dc16c3e2e2b9e3e71baaccc67bbe727e9d68ab (patch) | |
| tree | 9914701a22acd54cb4ed8bead7cb2430521567da | |
| parent | 014cce3dc49f5b0bfd7fbb1940ed661c9fc7bbd7 (diff) | |
i965: Don't dead-code eliminate instructions that write to the accumulator.
Reviewed-by: Paul Berry <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_fs.cpp | 16 | ||||
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_vec4.cpp | 16 |
2 files changed, 30 insertions, 2 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index b2c9f5a8e32..b83aca447e5 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -1846,7 +1846,21 @@ fs_visitor::dead_code_eliminate() if (inst->dst.file == GRF) { assert(this->virtual_grf_end[inst->dst.reg] >= pc); if (this->virtual_grf_end[inst->dst.reg] == pc) { - inst->remove(); + /* Don't dead code eliminate instructions that write to the + * accumulator as a side-effect. Instead just set the destination + * to the null register to free it. + */ + switch (inst->opcode) { + case BRW_OPCODE_ADDC: + case BRW_OPCODE_SUBB: + case BRW_OPCODE_MACH: + inst->dst.file = ARF; + inst->dst.reg = BRW_ARF_NULL; + break; + default: + inst->remove(); + break; + } progress = true; } } diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp index 75c3d344b5e..790ff2ebc72 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp @@ -314,7 +314,21 @@ vec4_visitor::dead_code_eliminate() if (inst->dst.file == GRF) { assert(this->virtual_grf_end[inst->dst.reg] >= pc); if (this->virtual_grf_end[inst->dst.reg] == pc) { - inst->remove(); + /* Don't dead code eliminate instructions that write to the + * accumulator as a side-effect. Instead just set the destination + * to the null register to free it. + */ + switch (inst->opcode) { + case BRW_OPCODE_ADDC: + case BRW_OPCODE_SUBB: + case BRW_OPCODE_MACH: + inst->dst.file = ARF; + inst->dst.reg = BRW_ARF_NULL; + break; + default: + inst->remove(); + break; + } progress = true; } } |