aco/ra: fix phi operand renaming

In case one operand was renamed and another operand came
from an incomplete phi, it could happen, that the original
name was not restored.

This has no impact on the code, but ensures correct SSA
is maintained during RA.

Cc: mesa-stable
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8109>

src/amd/compiler/aco_register_allocation.cpp

@@ -1615,6 +1615,11 @@ Temp handle_live_in(ra_ctx& ctx, Temp val, Block* block)
             phi->operands[i].setFixed(ctx.assignments[ops[i].id()].reg);
             if (ops[i].regClass() == new_val.regClass())
                ctx.affinities[new_val.id()] = ops[i].id();
+            /* make sure the operand gets it's original name in case
+             * it comes from an incomplete phi */
+            std::unordered_map<unsigned, phi_info>::iterator it = ctx.phi_map.find(ops[i].id());
+            if (it != ctx.phi_map.end())
+               it->second.uses.emplace(phi.get());
          }
          ctx.assignments.emplace_back();
          assert(ctx.assignments.size() == ctx.program->peekAllocationId());