<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Fri, May 27, 2016 at 7:06 PM, Francisco Jerez <<a href="mailto:currojerez@riseup.net" target="_blank">currojerez@riseup.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This requires using a bitset instead of a boolean flag to keep track of the GRFs we've seen a generating instruction for already. The search loop continues until all instructions initializing the value of the source VGRF have been found, or it is determined that coalescing is not possible. --- src/mesa/drivers/dri/i965/brw_fs.cpp | 46 ++++++++++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 10 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index 4062ea2..50552cb 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -2782,6 +2782,20 @@ fs_visitor::opt_redundant_discard_jumps() return progress; } +/** + * Compute a bitmask with GRF granularity with a bit set for each GRF starting + * from \p r which overlaps the region starting at \p r and spanning \p n GRF + * units. + */ +static inline unsigned +mask_relative_to(const fs_reg &r, const fs_reg &s, unsigned n) +{ + const int rel_offset = (reg_offset(s) - reg_offset(r)) / REG_SIZE; + assert(reg_space(r) == reg_space(s) && + rel_offset >= 0 && rel_offset < int(8 * sizeof(unsigned))); </blockquote><div> </div><div>Isn't that rel_offset < REG_SIZE? Or do you mean "unsigned-many bits? </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> + return ((1 << n) - 1) << rel_offset; +} + bool fs_visitor::compute_to_mrf() { @@ -2813,10 +2827,12 @@ fs_visitor::compute_to_mrf() if (this->virtual_grf_end[inst->src[0].nr] > ip) continue; - /* Found a move of a GRF to a MRF. Let's see if we can go - * rewrite the thing that made this GRF to write into the MRF. + /* Found a move of a GRF to a MRF. Let's see if we can go rewrite the + * things that computed the value of all GRFs of the source region. The + * regs_left bitset keeps track of the registers we haven't yet found a + * generating instruction for. */ - bool found = false; + unsigned regs_left = (1 << inst->regs_read(0)) - 1; foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst) { if (regions_overlap(scan_inst->dst, scan_inst->regs_written * REG_SIZE, @@ -2855,10 +2871,11 @@ fs_visitor::compute_to_mrf() } } - if (scan_inst->dst.reg_offset == inst->src[0].reg_offset) - found = true; - - break; + /* Clear the bits for any registers this instruction overwrites. */ + regs_left &= ~mask_relative_to( + inst->src[0], scan_inst->dst, scan_inst->regs_written); + if (!regs_left) + break; </blockquote><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> } /* We don't handle control flow here. Most computation of @@ -2901,14 +2918,21 @@ fs_visitor::compute_to_mrf() } } - if (!found) + if (regs_left) continue; - /* Found all generating instructions of our MRF's source value. + /* Found all generating instructions of our MRF's source value, so it + * should be safe to rewrite them to point to the MRF directly. */ + regs_left = (1 << inst->regs_read(0)) - 1; + foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst) { if (regions_overlap(scan_inst->dst, scan_inst->regs_written * REG_SIZE, inst->src[0], inst->regs_read(0) * REG_SIZE)) { + /* Clear the bits for any registers this instruction overwrites. */ + regs_left &= ~mask_relative_to( + inst->src[0], scan_inst->dst, scan_inst->regs_written); + const unsigned rel_offset = (reg_offset(scan_inst->dst) - reg_offset(inst->src[0])) / REG_SIZE; @@ -2935,10 +2959,12 @@ fs_visitor::compute_to_mrf() scan_inst->dst.file = MRF; scan_inst->dst.reg_offset = 0; scan_inst->saturate |= inst->saturate; - break; + if (!regs_left) + break; } } + assert(!regs_left); inst->remove(block); progress = true; } -- 2.7.3 _______________________________________________ mesa-dev mailing list <a href="mailto:mesa-dev@lists.freedesktop.org">mesa-dev@lists.freedesktop.org</a> <a href="https://lists.freedesktop.org/mailman/listinfo/mesa-dev" rel="noreferrer" target="_blank">https://lists.freedesktop.org/mailman/listinfo/mesa-dev</a> </blockquote></div> </div></div>