aco: fix get_temp_reg_changes with clobbered operands

The spiller might have tried to spill a live-through first or second
s_fmac_f32 operand, but this wouldn't have reduced the SGPRs if the third
operand wasn't killed

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13038
Fixes: d6cb45dbb0 ("aco/spill: Allow spilling live-through operands")
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34699>
(cherry picked from commit 7fe84024cb0985c2ab676d3e83520e5213db05df)

.pick_status.json

@@ -1194,7 +1194,7 @@
         "description": "aco: fix get_temp_reg_changes with clobbered operands",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "d6cb45dbb03941edd65c948a243e73774184eeee",
         "notes": null

src/amd/compiler/aco_live_var_analysis.cpp

@@ -67,6 +67,8 @@ RegisterDemand get_temp_reg_changes(Instruction* instr)
    for (Operand op : instr->operands) {
       if (op.isFirstKillBeforeDef() || op.isCopyKill())
          available_def_space -= op.getTemp();
+      else if (op.isClobbered() && !op.isKill())
+         available_def_space -= op.getTemp();
    }
 
    return available_def_space;