From: Rhys Perry <pendingchaos02@gmail.com>
Date: Tue, 7 Jul 2020 12:10:38 +0000 (+0100)
Subject: aco: rewrite graph coloring in spiller
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=47d7e1e6628616f678b353d29daa23595d6a7c42;p=mesa.git

aco: rewrite graph coloring in spiller

I don't think this is much of an optimization in the typical case, but for
very complex shaders this should work much better.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5805>
---

diff --git a/src/amd/compiler/aco_spill.cpp b/src/amd/compiler/aco_spill.cpp
index 7db3248e20f..faba524b76d 100644
--- a/src/amd/compiler/aco_spill.cpp
+++ b/src/amd/compiler/aco_spill.cpp
@@ -1327,145 +1327,131 @@ Temp load_scratch_resource(spill_ctx& ctx, Temp& scratch_offset,
                      Operand(rsrc_conf));
 }
 
-void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
-   std::map<uint32_t, uint32_t> sgpr_slot;
-   std::map<uint32_t, uint32_t> vgpr_slot;
-   std::vector<bool> is_assigned(ctx.interferences.size());
+void add_interferences(spill_ctx& ctx, std::vector<bool>& is_assigned,
+                       std::vector<uint32_t>& slots, std::vector<bool>& slots_used,
+                       unsigned id)
+{
+   RegType type = ctx.interferences[id].first.type();
 
-   /* first, handle affinities: just merge all interferences into both spill ids */
-   for (std::vector<uint32_t>& vec : ctx.affinities) {
-      for (unsigned i = 0; i < vec.size(); i++) {
-         for (unsigned j = i + 1; j < vec.size(); j++) {
-            assert(vec[i] != vec[j]);
-            for (uint32_t id : ctx.interferences[vec[i]].second)
-               ctx.interferences[id].second.insert(vec[j]);
-            for (uint32_t id : ctx.interferences[vec[j]].second)
-               ctx.interferences[id].second.insert(vec[i]);
-            ctx.interferences[vec[i]].second.insert(ctx.interferences[vec[j]].second.begin(), ctx.interferences[vec[j]].second.end());
-            ctx.interferences[vec[j]].second.insert(ctx.interferences[vec[i]].second.begin(), ctx.interferences[vec[i]].second.end());
+   for (unsigned other : ctx.interferences[id].second) {
+      if (!is_assigned[other])
+         continue;
 
-            bool reloaded = ctx.is_reloaded[vec[i]] || ctx.is_reloaded[vec[j]];
-            ctx.is_reloaded[vec[i]] = reloaded;
-            ctx.is_reloaded[vec[j]] = reloaded;
+      RegClass other_rc = ctx.interferences[other].first;
+      if (other_rc.type() == type) {
+         unsigned slot = slots[other];
+         std::fill(slots_used.begin() + slot, slots_used.begin() + slot + other_rc.size(), true);
+      }
+   }
+}
+
+unsigned find_available_slot(std::vector<bool>& used, unsigned wave_size,
+                             unsigned size, bool is_sgpr, unsigned *num_slots)
+{
+   unsigned wave_size_minus_one = wave_size - 1;
+   unsigned slot = 0;
+
+   while (true) {
+      bool available = true;
+      for (unsigned i = 0; i < size; i++) {
+         if (slot + i < used.size() && used[slot + i]) {
+            available = false;
+            break;
          }
       }
+      if (!available) {
+         slot++;
+         continue;
+      }
+
+      if (is_sgpr && ((slot & wave_size_minus_one) > wave_size - size)) {
+         slot = align(slot, wave_size);
+         continue;
+      }
+
+      std::fill(used.begin(), used.end(), false);
+
+      if (slot + size > used.size())
+         used.resize(slot + size);
+
+      return slot;
    }
-   for (ASSERTED uint32_t i = 0; i < ctx.interferences.size(); i++)
-      for (ASSERTED uint32_t id : ctx.interferences[i].second)
-         assert(i != id);
+}
 
-   /* for each spill slot, assign as many spill ids as possible */
-   std::vector<std::set<uint32_t>> spill_slot_interferences;
-   unsigned slot_idx = 0;
-   bool done = false;
-
-   /* assign sgpr spill slots */
-   while (!done) {
-      done = true;
-      for (unsigned id = 0; id < ctx.interferences.size(); id++) {
-         if (is_assigned[id] || !ctx.is_reloaded[id])
-            continue;
-         if (ctx.interferences[id].first.type() != RegType::sgpr)
-            continue;
+void assign_spill_slots_helper(spill_ctx& ctx, RegType type,
+                               std::vector<bool>& is_assigned,
+                               std::vector<uint32_t>& slots,
+                               unsigned *num_slots)
+{
+   std::vector<bool> slots_used(*num_slots);
 
-         /* check interferences */
-         bool interferes = false;
-         for (unsigned i = slot_idx; i < slot_idx + ctx.interferences[id].first.size(); i++) {
-            if (i == spill_slot_interferences.size())
-               spill_slot_interferences.emplace_back(std::set<uint32_t>());
-            if (spill_slot_interferences[i].find(id) != spill_slot_interferences[i].end() || i / ctx.wave_size != slot_idx / ctx.wave_size) {
-               interferes = true;
-               break;
-            }
-         }
-         if (interferes) {
-            done = false;
+   /* assign slots for ids with affinities first */
+   for (std::vector<uint32_t>& vec : ctx.affinities) {
+      if (ctx.interferences[vec[0]].first.type() != type)
+         continue;
+
+      for (unsigned id : vec) {
+         if (!ctx.is_reloaded[id])
             continue;
-         }
 
-         /* we found a spill id which can be assigned to current spill slot */
-         sgpr_slot[id] = slot_idx;
-         is_assigned[id] = true;
-         for (unsigned i = slot_idx; i < slot_idx + ctx.interferences[id].first.size(); i++)
-            spill_slot_interferences[i].insert(ctx.interferences[id].second.begin(), ctx.interferences[id].second.end());
-
-         /* add all affinities: there are no additional interferences */
-         for (std::vector<uint32_t>& vec : ctx.affinities) {
-            bool found_affinity = false;
-            for (uint32_t entry : vec) {
-               if (entry == id) {
-                  found_affinity = true;
-                  break;
-               }
-            }
-            if (!found_affinity)
-               continue;
-            for (uint32_t entry : vec) {
-               sgpr_slot[entry] = slot_idx;
-               is_assigned[entry] = true;
-            }
+         add_interferences(ctx, is_assigned, slots, slots_used, id);
+      }
+
+      unsigned slot = find_available_slot(slots_used, ctx.wave_size,
+                                          ctx.interferences[vec[0]].first.size(),
+                                          type == RegType::sgpr, num_slots);
+
+      for (unsigned id : vec) {
+         assert(!is_assigned[id]);
+
+         if (ctx.is_reloaded[id]) {
+            slots[id] = slot;
+            is_assigned[id] = true;
          }
       }
-      slot_idx++;
    }
 
-   unsigned sgpr_spill_slots = spill_slot_interferences.size();
-   spill_slot_interferences.clear();
-   slot_idx = 0;
-   done = false;
+   /* assign slots for ids without affinities */
+   for (unsigned id = 0; id < ctx.interferences.size(); id++) {
+      if (is_assigned[id] || !ctx.is_reloaded[id] || ctx.interferences[id].first.type() != type)
+         continue;
 
-   /* assign vgpr spill slots */
-   while (!done) {
-      done = true;
-      for (unsigned id = 0; id < ctx.interferences.size(); id++) {
-         if (is_assigned[id] || !ctx.is_reloaded[id])
-            continue;
-         if (ctx.interferences[id].first.type() != RegType::vgpr)
-            continue;
+      add_interferences(ctx, is_assigned, slots, slots_used, id);
 
-         /* check interferences */
-         bool interferes = false;
-         for (unsigned i = slot_idx; i < slot_idx + ctx.interferences[id].first.size(); i++) {
-            if (i == spill_slot_interferences.size())
-               spill_slot_interferences.emplace_back(std::set<uint32_t>());
-            /* check for interference and ensure that vector regs are stored next to each other */
-            if (spill_slot_interferences[i].find(id) != spill_slot_interferences[i].end()) {
-               interferes = true;
-               break;
-            }
-         }
-         if (interferes) {
-            done = false;
-            continue;
-         }
+      unsigned slot = find_available_slot(slots_used, ctx.wave_size,
+                                          ctx.interferences[id].first.size(),
+                                          type == RegType::sgpr, num_slots);
 
-         /* we found a spill id which can be assigned to current spill slot */
-         vgpr_slot[id] = slot_idx;
-         is_assigned[id] = true;
-         for (unsigned i = slot_idx; i < slot_idx + ctx.interferences[id].first.size(); i++)
-            spill_slot_interferences[i].insert(ctx.interferences[id].second.begin(), ctx.interferences[id].second.end());
-
-         /* add all affinities: there are no additional interferences */
-         for (std::vector<uint32_t>& vec : ctx.affinities) {
-            bool found_affinity = false;
-            for (uint32_t entry : vec) {
-               if (entry == id) {
-                  found_affinity = true;
-                  break;
-               }
-            }
-            if (!found_affinity)
-               continue;
-            for (uint32_t entry : vec) {
-               vgpr_slot[entry] = slot_idx;
-               is_assigned[entry] = true;
-            }
+      slots[id] = slot;
+      is_assigned[id] = true;
+   }
+
+   *num_slots = slots_used.size();
+}
+
+void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
+   std::vector<uint32_t> slots(ctx.interferences.size());
+   std::vector<bool> is_assigned(ctx.interferences.size());
+
+   /* first, handle affinities: just merge all interferences into both spill ids */
+   for (std::vector<uint32_t>& vec : ctx.affinities) {
+      for (unsigned i = 0; i < vec.size(); i++) {
+         for (unsigned j = i + 1; j < vec.size(); j++) {
+            assert(vec[i] != vec[j]);
+            bool reloaded = ctx.is_reloaded[vec[i]] || ctx.is_reloaded[vec[j]];
+            ctx.is_reloaded[vec[i]] = reloaded;
+            ctx.is_reloaded[vec[j]] = reloaded;
          }
       }
-      slot_idx++;
    }
+   for (ASSERTED uint32_t i = 0; i < ctx.interferences.size(); i++)
+      for (ASSERTED uint32_t id : ctx.interferences[i].second)
+         assert(i != id);
 
-   unsigned vgpr_spill_slots = spill_slot_interferences.size();
+   /* for each spill slot, assign as many spill ids as possible */
+   unsigned sgpr_spill_slots = 0, vgpr_spill_slots = 0;
+   assign_spill_slots_helper(ctx, RegType::sgpr, is_assigned, slots, &sgpr_spill_slots);
+   assign_spill_slots_helper(ctx, RegType::vgpr, is_assigned, slots, &vgpr_spill_slots);
 
    for (unsigned id = 0; id < is_assigned.size(); id++)
       assert(is_assigned[id] || !ctx.is_reloaded[id]);
@@ -1478,10 +1464,7 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
                continue;
             assert(ctx.is_reloaded[vec[i]] == ctx.is_reloaded[vec[j]]);
             assert(ctx.interferences[vec[i]].first.type() == ctx.interferences[vec[j]].first.type());
-            if (ctx.interferences[vec[i]].first.type() == RegType::sgpr)
-               assert(sgpr_slot[vec[i]] == sgpr_slot[vec[j]]);
-            else
-               assert(vgpr_slot[vec[i]] == vgpr_slot[vec[j]]);
+            assert(slots[vec[i]] == slots[vec[j]]);
          }
       }
    }
@@ -1531,8 +1514,8 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
             bool can_destroy = true;
             for (std::pair<Temp, uint32_t> pair : ctx.spills_exit[block.linear_preds[0]]) {
 
-               if (sgpr_slot.find(pair.second) != sgpr_slot.end() &&
-                   sgpr_slot[pair.second] / ctx.wave_size == i) {
+               if (ctx.interferences[pair.second].first.type() == RegType::sgpr &&
+                   slots[pair.second] / ctx.wave_size == i) {
                   can_destroy = false;
                   break;
                }
@@ -1553,10 +1536,12 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
 
             if (!ctx.is_reloaded[spill_id]) {
                /* never reloaded, so don't spill */
-            } else if (vgpr_slot.find(spill_id) != vgpr_slot.end()) {
+            } else if (!is_assigned[spill_id]) {
+               unreachable("No spill slot assigned for spill id");
+            } else if (ctx.interferences[spill_id].first.type() == RegType::vgpr) {
                /* spill vgpr */
                ctx.program->config->spilled_vgprs += (*it)->operands[0].size();
-               uint32_t spill_slot = vgpr_slot[spill_id];
+               uint32_t spill_slot = slots[spill_id];
                bool add_offset_to_sgpr = ctx.program->config->scratch_bytes_per_wave / ctx.program->wave_size + vgpr_spill_slots * 4 > 4096;
                unsigned base_offset = add_offset_to_sgpr ? 0 : ctx.program->config->scratch_bytes_per_wave / ctx.program->wave_size;
 
@@ -1586,10 +1571,10 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
                } else {
                   bld.mubuf(opcode, scratch_rsrc, Operand(v1), scratch_offset, temp, offset, false);
                }
-            } else if (sgpr_slot.find(spill_id) != sgpr_slot.end()) {
+            } else {
                ctx.program->config->spilled_sgprs += (*it)->operands[0].size();
 
-               uint32_t spill_slot = sgpr_slot[spill_id];
+               uint32_t spill_slot = slots[spill_id];
 
                /* check if the linear vgpr already exists */
                if (vgpr_spill_temps[spill_slot / ctx.wave_size] == Temp()) {
@@ -1615,17 +1600,17 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
                spill->operands[1] = Operand(spill_slot % ctx.wave_size);
                spill->operands[2] = (*it)->operands[0];
                instructions.emplace_back(aco_ptr<Instruction>(spill));
-            } else {
-               unreachable("No spill slot assigned for spill id");
             }
 
          } else if ((*it)->opcode == aco_opcode::p_reload) {
             uint32_t spill_id = (*it)->operands[0].constantValue();
             assert(ctx.is_reloaded[spill_id]);
 
-            if (vgpr_slot.find(spill_id) != vgpr_slot.end()) {
+            if (!is_assigned[spill_id]) {
+               unreachable("No spill slot assigned for spill id");
+            } else if (ctx.interferences[spill_id].first.type() == RegType::vgpr) {
                /* reload vgpr */
-               uint32_t spill_slot = vgpr_slot[spill_id];
+               uint32_t spill_slot = slots[spill_id];
                bool add_offset_to_sgpr = ctx.program->config->scratch_bytes_per_wave / ctx.program->wave_size + vgpr_spill_slots * 4 > 4096;
                unsigned base_offset = add_offset_to_sgpr ? 0 : ctx.program->config->scratch_bytes_per_wave / ctx.program->wave_size;
 
@@ -1654,8 +1639,8 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
                } else {
                   bld.mubuf(opcode, def, scratch_rsrc, Operand(v1), scratch_offset, offset, false);
                }
-            } else if (sgpr_slot.find(spill_id) != sgpr_slot.end()) {
-               uint32_t spill_slot = sgpr_slot[spill_id];
+            } else {
+               uint32_t spill_slot = slots[spill_id];
                reload_in_loop[spill_slot / ctx.wave_size] = block.loop_nest_depth > 0;
 
                /* check if the linear vgpr already exists */
@@ -1682,8 +1667,6 @@ void assign_spill_slots(spill_ctx& ctx, unsigned spills_to_vgpr) {
                reload->operands[1] = Operand(spill_slot % ctx.wave_size);
                reload->definitions[0] = (*it)->definitions[0];
                instructions.emplace_back(aco_ptr<Instruction>(reload));
-            } else {
-               unreachable("No spill slot assigned for spill id");
             }
          } else if (!ctx.remat_used.count(it->get()) || ctx.remat_used[it->get()]) {
             instructions.emplace_back(std::move(*it));