diff options
| author | Matt Turner <mattst88@gmail.com> | 2016-05-02 23:32:13 -0700 |
|---|---|---|
| committer | Matt Turner <mattst88@gmail.com> | 2016-05-05 10:18:28 -0700 |
| commit | f01d92f4734a7ca62926dceda1d004c0cb10548c (patch) | |
| tree | f5c3ac8ddaccf61de72f36a227ad60a22bb77c8c | |
| parent | 9d86a5eea79ac30bb90af363c66a5ba8529b37d8 (diff) | |
i965/fs: Don't follow pow with an instruction with two dest regs.
Beginning with commit 7b208a73, Unigine Valley began hanging the GPU on
Gen >= 8 platforms.
Evidently that commit allowed the scheduler to make different choices
that somehow finally ran afoul of a hardware bug in which POW and FDIV
instructions may not be followed by an instruction with two destination
registers (including compressed instructions). I presume the conditions
are more complex than that, but the internal hardware bug report (BDWGFX
bug_de 1696294) does not contain much more information.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94924
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com> [v1]
Tested-by: Mark Janes <mark.a.janes@intel.com> [v1]
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_fs_generator.cpp | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp index 8654ca4d0a..ff8d37e2c0 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp @@ -1726,6 +1726,24 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width) unsigned int last_insn_offset = p->next_insn_offset; bool multiple_instructions_emitted = false; + /* From the Broadwell PRM, Volume 7, "3D-Media-GPGPU", in the + * "Register Region Restrictions" section: for BDW, SKL: + * + * "A POW/FDIV operation must not be followed by an instruction + * that requires two destination registers." + * + * The documentation is often lacking annotations for Atom parts, + * and empirically this affects CHV as well. + */ + if (devinfo->gen >= 8 && + p->nr_insn > 1 && + brw_inst_opcode(devinfo, brw_last_inst) == BRW_OPCODE_MATH && + brw_inst_math_function(devinfo, brw_last_inst) == BRW_MATH_FUNCTION_POW && + inst->dst.component_size(inst->exec_size) > REG_SIZE) { + brw_NOP(p); + last_insn_offset = p->next_insn_offset; + } + if (unlikely(debug_flag)) annotate(p->devinfo, &annotation, cfg, inst, p->next_insn_offset); |