r600/sfn: change register ID of dummy dest register

Handle it correctly in the assembler, live range evaluation
and RA.

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37321>

src/gallium/drivers/r600/sfn/sfn_alu_defines.h

@@ -18,6 +18,7 @@ namespace r600 {
 static const int g_registers_end = 123;
 static const int g_clause_local_start = 124;
 static const int g_clause_local_end = 128;
+static const int g_registers_unused = 0x7fffffff;
 
 /* ALU op2 instructions 17:7 top three bits always zero. */
 enum EAluOp {

src/gallium/drivers/r600/sfn/sfn_assembler.cpp

@@ -1190,7 +1190,7 @@ AssamblerVisitor::emit_loop_cont()
 bool
 AssamblerVisitor::copy_dst(r600_bytecode_alu_dst& dst, const Register& d, bool write)
 {
-   if (write && d.sel() > g_clause_local_end) {
+   if (write && d.sel() > g_clause_local_end && d.sel() != g_registers_unused) {
       R600_ASM_ERR("shader_from_nir: Don't support more then 123 GPRs + 4 clause "
                    "local, but try using %d\n",
                    d.sel());
@@ -1198,7 +1198,7 @@ AssamblerVisitor::copy_dst(r600_bytecode_alu_dst& dst, const Register& d, bool w
       return false;
    }
 
-   dst.sel = d.sel();
+   dst.sel = d.sel() != g_registers_unused ? d.sel() : g_registers_end;
    dst.chan = d.chan();
 
    if (m_last_addr && m_last_addr->equal_to(d))

src/gallium/drivers/r600/sfn/sfn_instr_alu.cpp

@@ -296,7 +296,10 @@ AluInstr::do_print(std::ostream& os) const
 
       if (m_dest) {
          if (has_alu_flag(alu_write) || m_dest->has_flag(Register::addr_or_idx)) {
-            os << " " << *m_dest;
+            if (unlikely(m_dest->sel() == g_registers_unused))
+               os << " ()" << "." << swzchar[dest_chan()];
+            else
+               os << " " << *m_dest;
          } else {
             os << " __"
                << "." << swzchar[m_dest->chan()];

src/gallium/drivers/r600/sfn/sfn_liverangeevaluator.cpp

@@ -442,7 +442,7 @@ LiveRangeInstrVisitor::record_write(int block, const Register *reg)
          auto& rav = m_register_access(array(i, reg->chan()));
          rav.record_write(block, m_line > 0 ? m_line - 1 : 0, m_current_scope);
       }
-   } else {
+   } else if (reg->sel() != g_registers_unused) {
       auto& ra = m_register_access(*reg);
       sfn_log << SfnLog::merge << *reg << " write:" << block << ":" << m_line << "\n";
       ra.record_write(block, m_line, m_current_scope);

src/gallium/drivers/r600/sfn/sfn_ra.cpp

@@ -210,7 +210,7 @@ scalar_allocation(LiveRangeMap& lrm, const Interference& interference)
    for (int comp = 0; comp < 4; ++comp) {
       auto& live_ranges = lrm.component(comp);
       for (auto& r : live_ranges) {
-         if (r.m_color != -1)
+         if (r.m_color != g_registers_unused)
             continue;
 
          if (r.m_start == -1 && r.m_end == -1)
@@ -272,7 +272,7 @@ scalar_clause_local_allocation (LiveRangeMap& lrm, const Interference&  interfer
                   << " ], AC: " << r.m_alu_clause_local
                   << " Color; " << r.m_color << "\n";
 
-         if (r.m_color != -1)
+         if (r.m_color != g_registers_unused)
             continue;
 
          if (r.m_start == -1 &&

src/gallium/drivers/r600/sfn/sfn_valuefactory.cpp

@@ -616,7 +616,7 @@ ValueFactory::dest_from_string(const std::string& s, int *dest_chan)
 
    assert(s.length() >= 4);
 
-   assert(strchr("ARS_", s[0]));
+   assert(strchr("ARS_(", s[0]));
 
    split_register_string(s, index_str, size_str, swizzle_str, pin_str);
 
@@ -625,6 +625,8 @@ ValueFactory::dest_from_string(const std::string& s, int *dest_chan)
       /* Since these instructions still may use or switch to a different
        * channel we have to create a new instance for each occurrence */
       sel = -1;
+   } else if (s[0] == '(') {
+      sel = g_registers_unused;
    } else {
       std::istringstream n(index_str);
       n >> sel;
@@ -644,6 +646,7 @@ ValueFactory::dest_from_string(const std::string& s, int *dest_chan)
    case '_':
       pool = vp_ignore;
       break;
+   case '(':
    case 'S':
       pool = vp_ssa;
       break;
@@ -982,7 +985,7 @@ ValueFactory::prepare_live_range_map()
             result.append_register(a);
          }
       } else {
-         if (reg->chan() < 4)
+         if (reg->chan() < 4 && reg->sel() != g_registers_unused)
             result.append_register(reg);
       }
    }

src/gallium/drivers/r600/sfn/sfn_valuefactory.h

@@ -33,7 +33,7 @@ struct LiveRangeEntry {
    int m_start{-1};
    int m_end{-1};
    int m_index{-1};
-   int m_color{-1};
+   int m_color{g_registers_unused};
    bool m_alu_clause_local{false};
    std::bitset<use_unspecified> m_use;
    Register *m_register;
@@ -311,7 +311,8 @@ private:
    uint32_t m_nowrite_idx;
 
    RegisterVec4 m_dummy_dest_pinned{
-      g_registers_end, pin_chan, {0, 1, 2, 3}
+      g_registers_unused, true, {0, 1, 2, 3},
+        pin_chan
    };
    ChannelCounts m_channel_counts;
    uint32_t m_required_array_registers{0};

src/gallium/drivers/r600/sfn/sfn_virtualvalues.cpp

@@ -49,7 +49,7 @@ VirtualValue::VirtualValue(int sel, int chan, Pin pin):
     m_pins(pin)
 {
 #if __cpp_exceptions >= 199711L
-   ASSERT_OR_THROW(m_sel < virtual_register_base || pin != pin_fully,
+   ASSERT_OR_THROW(m_sel < g_registers_end || pin != pin_fully,
                    "Register is virtual but pinned to sel");
 #endif
 }