diff --git a/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.cpp b/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.cpp
index 0b0f29c5ff9..6d40e185500 100644
--- a/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.cpp
+++ b/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.cpp
@@ -15,7 +15,11 @@
 
 namespace r600 {
 
-AluGroup::AluGroup() { std::fill(m_slots.begin(), m_slots.end(), nullptr); }
+AluGroup::AluGroup()
+{
+   std::fill(m_slots.begin(), m_slots.end(), nullptr);
+   m_free_slots = has_t() ? 0x1f : 0xf;
+}
 
 bool
 AluGroup::add_instruction(AluInstr *instr)
@@ -114,6 +118,7 @@ AluGroup::add_trans_instructions(AluInstr *instr)
           update_indirect_access(instr)) {
          m_readports_evaluator = readports_evaluator;
          m_slots[4] = instr;
+         m_free_slots &= ~0x10;
          instr->pin_sources_to_chan();
          sfn_log << SfnLog::schedule << "T: " << *instr << "\n";
 
@@ -127,17 +132,6 @@ AluGroup::add_trans_instructions(AluInstr *instr)
    return false;
 }
 
-int
-AluGroup::free_slots() const
-{
-   int free_mask = 0;
-   for (int i = 0; i < s_max_slots; ++i) {
-      if (!m_slots[i])
-         free_mask |= 1 << i;
-   }
-   return free_mask;
-}
-
 bool
 AluGroup::add_vec_instructions(AluInstr *instr)
 {   
@@ -261,6 +255,7 @@ AluGroup::try_readport(AluInstr *instr, AluBankSwizzle cycle)
        update_indirect_access(instr)) {
       m_readports_evaluator = readports_evaluator;
       m_slots[preferred_chan] = instr;
+      m_free_slots &= ~(1 << preferred_chan);
       m_has_lds_op |= instr->has_lds_access();
       sfn_log << SfnLog::schedule << "V: " << *instr << "\n";
       auto dest = instr->dest();
diff --git a/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.h b/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.h
index e8cb0aff18e..a16d6e67ea6 100644
--- a/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.h
+++ b/src/gallium/drivers/r600/sfn/sfn_instr_alugroup.h
@@ -46,11 +46,13 @@ public:
 
    static void set_chipclass(r600_chip_class chip_class);
 
-   int free_slots() const;
-
    auto addr() const { return std::make_pair(m_addr_used, m_addr_is_index); }
 
    uint32_t slots() const override;
+   uint8_t free_slot_mask() const
+   {
+      return m_free_slots;
+   }
 
    AluInstr::SrcValues get_kconsts() const;
 
@@ -105,6 +107,8 @@ private:
    bool m_addr_for_src{false};
    bool m_has_kill_op{false};
    AluInstr *m_origin{nullptr};
+
+   uint8_t m_free_slots;
 };
 
 } // namespace r600
diff --git a/src/gallium/drivers/r600/sfn/sfn_scheduler.cpp b/src/gallium/drivers/r600/sfn/sfn_scheduler.cpp
index adbe69c3bda..e1f03d01ff7 100644
--- a/src/gallium/drivers/r600/sfn/sfn_scheduler.cpp
+++ b/src/gallium/drivers/r600/sfn/sfn_scheduler.cpp
@@ -591,7 +591,7 @@ BlockScheduler::schedule_alu(Shader::ShaderBlocks& out_blocks)
 
    assert(group);
 
-   int free_slots = group->free_slots();
+   int free_slots = group->free_slot_mask();
 
    while (free_slots && has_alu_ready) {
       if (!alu_vec_ready.empty())