Mesa (master): aco: fix underestimated pressure in spiller when a phi has a killed def

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Module: Mesa
Branch: master
Commit: 5a941f4d6dc1ea1d08ba3d9bfe4c5add97b0fde4
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=5a941f4d6dc1ea1d08ba3d9bfe4c5add97b0fde4

Author: Rhys Perry <pendingchaos02 at gmail.com>
Date:   Tue Jul  7 18:16:47 2020 +0100

aco: fix underestimated pressure in spiller when a phi has a killed def

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

---

 src/amd/compiler/aco_spill.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/amd/compiler/aco_spill.cpp b/src/amd/compiler/aco_spill.cpp
index 62ab69a045b..7db3248e20f 100644
--- a/src/amd/compiler/aco_spill.cpp
+++ b/src/amd/compiler/aco_spill.cpp
@@ -604,6 +604,17 @@ RegisterDemand init_live_in_vars(spill_ctx& ctx, Block* block, unsigned block_id
          }
       }
    } else {
+      for (unsigned i = 0; i < idx; i++) {
+         aco_ptr<Instruction>& instr = block->instructions[i];
+         assert(is_phi(instr));
+         /* Killed phi definitions increase pressure in the predecessor but not
+          * the block they're in. Since the loops below are both to control
+          * pressure of the start of this block and the ends of it's
+          * predecessors, we need to count killed unspilled phi definitions here. */
+         if (instr->definitions[0].isKill() &&
+             !ctx.spills_entry[block_idx].count(instr->definitions[0].getTemp()))
+            reg_pressure += instr->definitions[0].getTemp();
+      }
       idx--;
    }
    reg_pressure += ctx.register_demand[block_idx][idx] - spilled_registers;