<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Mon, Sep 29, 2014 at 9:50 AM, Matt Turner <<a href="mailto:mattst88@gmail.com" target="_blank">mattst88@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Fri, Sep 26, 2014 at 12:24 PM, Jason Ekstrand <<a href="mailto:jason@jlekstrand.net">jason@jlekstrand.net</a>> wrote: > This commit reworks copy propagation a bit to support propagating the > copying of partial registers. This comes up every time we have pull > constants because we do a pull constant read immediately followed by a move > to splat the one component of the out to 8 or 16-wide. This allows us to > eliminate the copy and simply use the one component of the register. > > Shader DB results: > > total instructions in shared programs: 5044937 -> 5044428 (-0.01%) > instructions in affected programs: 66112 -> 65603 (-0.77%) > GAINED: 0 > LOST: 0 > > Signed-off-by: Jason Ekstrand <<a href="mailto:jason.ekstrand@intel.com">jason.ekstrand@intel.com</a>> > --- > src/mesa/drivers/dri/i965/brw_fs.h | 1 + > .../drivers/dri/i965/brw_fs_copy_propagation.cpp | 83 ++++++++++++++++------ > 2 files changed, 64 insertions(+), 20 deletions(-) > > diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h > index 50b5fc1..9b63114 100644 > --- a/src/mesa/drivers/dri/i965/brw_fs.h > +++ b/src/mesa/drivers/dri/i965/brw_fs.h > @@ -337,6 +337,7 @@ public: > bool opt_cse_local(bblock_t *block); > bool opt_copy_propagate(); > bool try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry); > + bool try_constant_propagate(fs_inst *inst, acp_entry *entry); > bool opt_copy_propagate_local(void *mem_ctx, bblock_t *block, > exec_list *acp); > void opt_drop_redundant_mov_to_flags(); > diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > index e5816df..a97dc04 100644 > --- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > +++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > @@ -277,24 +277,30 @@ is_logic_op(enum opcode opcode) > bool > fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry) > { > + if (inst->src[arg].file != GRF) > + return false; > + > if (entry->src.file == IMM) > return false; > + assert(entry->src.file == GRF || entry->src.file == UNIFORM); > > if (entry->opcode == SHADER_OPCODE_LOAD_PAYLOAD && > inst->opcode == SHADER_OPCODE_LOAD_PAYLOAD) > return false; > > - /* Bail if inst is reading more than entry is writing. */ > - if ((inst->regs_read(this, arg) * inst->src[arg].stride * > - type_sz(inst->src[arg].type)) > type_sz(entry->dst.type)) > + assert(entry->dst.file == GRF); > + if (inst->src[arg].reg != entry->dst.reg) > return false; > > - if (inst->src[arg].file != entry->dst.file || > - inst->src[arg].reg != entry->dst.reg || > - inst->src[arg].reg_offset != entry->dst.reg_offset || > - inst->src[arg].subreg_offset != entry->dst.subreg_offset) { > + /* Bail if inst is reading a range that isn't contained in the range > + * that entry is writing. > + */ > + int reg_size = dispatch_width * sizeof(float); > + if (inst->src[arg].reg_offset < entry->dst.reg_offset || > + (inst->src[arg].reg_offset * reg_size + inst->src[arg].subreg_offset + > + inst->regs_read(this, arg) * inst->src[arg].stride * reg_size) > > + (entry->dst.reg_offset + 1) * reg_size) > return false; > - } > > /* See resolve_ud_negate() and comment in brw_fs_emit.cpp. */ > if (inst->conditional_mod && > @@ -361,11 +367,39 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry) > > inst->src[arg].file = entry->src.file; > inst->src[arg].reg = entry->src.reg; > - inst->src[arg].reg_offset = entry->src.reg_offset; > - inst->src[arg].subreg_offset = entry->src.subreg_offset; > inst->src[arg].stride *= entry->src.stride; > inst->saturate = inst->saturate || entry->saturate; > > + switch (entry->src.file) { > + case BAD_FILE: > + case HW_REG: > + case UNIFORM: > + inst->src[arg].reg_offset = entry->src.reg_offset; > + inst->src[arg].subreg_offset = entry->src.subreg_offset; > + break; > + case GRF: > + { > + /* In this case, we have to deal with mapping parts of vgrfs to > + * other parts of vgrfs so we have to do some reg_offset magic. > + */ > + > + /* Compute the offset of inst->src[arg] relative to inst->dst */ > + assert(entry->dst.subreg_offset == 0); > + int rel_offset = inst->src[arg].reg_offset - entry->dst.reg_offset; > + int rel_suboffset = inst->src[arg].subreg_offset; > + > + /* Compute the final register offset (in bytes) */ > + int offset = entry->src.reg_offset * reg_size + entry->src.subreg_offset; > + offset += rel_offset * reg_size + rel_suboffset; > + inst->src[arg].reg_offset = offset / reg_size; > + inst->src[arg].subreg_offset = offset % reg_size; > + } > + break; > + default: > + unreachable("Invalid register file"); > + break; > + } > + > if (!inst->src[arg].abs) { > inst->src[arg].abs = entry->src.abs; > inst->src[arg].negate ^= entry->src.negate; > @@ -375,9 +409,8 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry) > } > > > -static bool > -try_constant_propagate(struct brw_context *brw, fs_inst *inst, > - acp_entry *entry) > +bool > +fs_visitor::try_constant_propagate(fs_inst *inst, acp_entry *entry) > { > bool progress = false; > > @@ -385,12 +418,22 @@ try_constant_propagate(struct brw_context *brw, fs_inst *inst, > return false; > > for (int i = inst->sources - 1; i >= 0; i--) { > - if (inst->src[i].file != entry->dst.file || > - inst->src[i].reg != entry->dst.reg || > - inst->src[i].reg_offset != entry->dst.reg_offset || > - inst->src[i].subreg_offset != entry->dst.subreg_offset || > - inst->src[i].type != entry->dst.type || > - inst->src[i].stride > 1) > + if (inst->src[i].file != GRF) > + continue; > + > + assert(entry->dst.file == GRF); > + if (inst->src[i].reg != entry->dst.reg || > + inst->src[i].type != entry->dst.type) > + continue; > + > + /* Bail if inst is reading a range that isn't contained in the range > + * that entry is writing. > + */ > + int reg_size = dispatch_width * sizeof(float); > + if (inst->src[i].reg_offset < entry->dst.reg_offset || > + (inst->src[i].reg_offset * reg_size + inst->src[i].subreg_offset + > + inst->regs_read(this, i) * inst->src[i].stride * reg_size) > > + (entry->dst.reg_offset + 1) * reg_size) > continue; </div></div>Does this bit, the constant propagation code, actually benefit from this? I guess it'd let an immediate loaded with a mov(16) be constant propagated into two SIMD8 instructions? That seems plausible, I was just a little surprised at first. </blockquote></div> </div><div class="gmail_extra">Yes, that's exactly what it's for </div></div>