diff --git a/.pick_status.json b/.pick_status.json
index 3e230bb8e4d..0e25b04e3f4 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -1634,7 +1634,7 @@
         "description": "aco: Don't exclude discardable parameters from register preservation",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null,
         "notes": null
diff --git a/src/amd/compiler/aco_nir_call_attribs.h b/src/amd/compiler/aco_nir_call_attribs.h
index d74fa63c969..777f1063c05 100644
--- a/src/amd/compiler/aco_nir_call_attribs.h
+++ b/src/amd/compiler/aco_nir_call_attribs.h
@@ -22,7 +22,13 @@ enum aco_nir_function_attribs {
 };
 
 enum aco_nir_parameter_attribs {
-   /* Parameter value is not used by any callee and does not need to be preserved */
+   /* This parameter's value may not be preserved across a callee. Unlike return parameters, the
+    * parameter's value is undefined on return. Callers must back up values of discardable
+    * parameters separately.
+    * Mostly used for tail calls, where parameters to the tail callee have different values than
+    * for the caller. In that case, on function return, the parameters will have been overwritten
+    * with the tail callee parameter values.
+    */
    ACO_NIR_PARAM_ATTRIB_DISCARDABLE = 0x1,
 };
 
diff --git a/src/amd/compiler/instruction_selection/aco_isel_helpers.cpp b/src/amd/compiler/instruction_selection/aco_isel_helpers.cpp
index f9bff68dce2..4255128bbd0 100644
--- a/src/amd/compiler/instruction_selection/aco_isel_helpers.cpp
+++ b/src/amd/compiler/instruction_selection/aco_isel_helpers.cpp
@@ -1034,8 +1034,7 @@ find_param_regs(Program* program, const ABI& abi, callee_info& info,
 
             param_demand += Temp(0, it2->rc);
 
-            it2->dst_info->needs_explicit_preservation =
-               regs == clobbered_regs && !it2->dst_info->discardable;
+            it2->dst_info->needs_explicit_preservation = regs == clobbered_regs;
             it2->dst_info->def.setPrecolored(*next_reg);
             for (unsigned i = 0; i < it2->rc.size(); ++i)
                BITSET_CLEAR(regs, next_reg->reg() + i);
@@ -1051,8 +1050,7 @@ find_param_regs(Program* program, const ABI& abi, callee_info& info,
             next_reg = next_reg->advance(required_padding * 4);
       }
       if (next_reg) {
-         params.back().dst_info->needs_explicit_preservation =
-            regs == clobbered_regs && !params.back().dst_info->discardable;
+         params.back().dst_info->needs_explicit_preservation = regs == clobbered_regs;
          param_demand += Temp(0, params.back().rc);
          params.back().dst_info->def.setPrecolored(*next_reg);
          BITSET_CLEAR_COUNT(regs, next_reg->reg(), params.back().rc.size());