r600/sfn: rework testing readport config for more than one source

When checking the readport config for a number of sources that
would be used in a multi-slot instruction, then return the index
of the source for which readport allocation fails.
With that we can later add a mov instruction to change the source
channels configuration.

In addition pass a std::array instead of a C-array to make the interface
more c++-like and prepare for the next patch.

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36860>

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

@@ -71,8 +71,8 @@ public:
    void visit(const UniformValue& value) override;
 };
 
-bool
-AluReadportReservation::schedule_vec_src(PVirtualValue src[3],
+unsigned
+AluReadportReservation::schedule_vec_src(const std::array<PVirtualValue, 3>& src,
                                          int nsrc,
                                          AluBankSwizzle swz)
 {
@@ -90,9 +90,12 @@ AluReadportReservation::schedule_vec_src(PVirtualValue src[3],
       visitor.cycle = cycle_vec(swz, i);
       visitor.isrc = i;
       src[i]->accept(visitor);
+      if (!visitor.success) {
+         return i;
+      }
    }
 
-   return visitor.success;
+   return nsrc;
 }
 
 bool

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

@@ -17,7 +17,9 @@ public:
    AluReadportReservation(const AluReadportReservation& orig) = default;
    AluReadportReservation& operator=(const AluReadportReservation& orig) = default;
 
-   bool schedule_vec_src(PVirtualValue src[3], int nsrc, AluBankSwizzle swz);
+   unsigned schedule_vec_src(const std::array<PVirtualValue, 3>& src,
+                             int nsrc,
+                             AluBankSwizzle swz);
 
    bool schedule_vec_instruction(const AluInstr& alu, AluBankSwizzle swz);
    bool schedule_trans_instruction(const AluInstr& alu, AluBankSwizzle swz);

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

@@ -711,7 +711,7 @@ AluInstr::check_readport_validation(PRegister old_src, PVirtualValue new_src) co
    assert(nsrc * m_alu_slots == m_src.size());
 
    for (int s = 0; s < m_alu_slots && success; ++s) {
-      PVirtualValue src[3];
+      std::array<PVirtualValue, 3> src;
       auto ireg = m_src.begin() + s * nsrc;
 
       for (unsigned i = 0; i < nsrc; ++i, ++ireg)
@@ -720,7 +720,7 @@ AluInstr::check_readport_validation(PRegister old_src, PVirtualValue new_src) co
       AluBankSwizzle bs = alu_vec_012;
       while (bs != alu_vec_unknown) {
          AluReadportReservation rpr = rpr_sum;
-         if (rpr.schedule_vec_src(src, nsrc, bs)) {
+         if (rpr.schedule_vec_src(src, nsrc, bs) == nsrc) {
             rpr_sum = rpr;
             break;
          }
@@ -877,7 +877,7 @@ AluInstr::split(ValueFactory& vf, AluGroup& group)
    assert(nsrc * m_alu_slots == m_src.size());
 
    for (int s = 0; s < m_alu_slots; ++s) {
-      PVirtualValue src[3];
+      std::array<PVirtualValue, 3> src;
       auto ireg = m_src.begin() + s * nsrc;
 
       for (unsigned i = 0; i < nsrc; ++i, ++ireg)
@@ -886,7 +886,7 @@ AluInstr::split(ValueFactory& vf, AluGroup& group)
       AluBankSwizzle bs = alu_vec_012;
       while (bs != alu_vec_unknown) {
          AluReadportReservation rpr = rr;
-         if (rpr.schedule_vec_src(src, nsrc, bs)) {
+         if (rpr.schedule_vec_src(src, nsrc, bs) == nsrc) {
             rr = rpr;
             break;
          }

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

@@ -327,16 +327,19 @@ bool AluGroup::replace_source(PRegister old_src, PVirtualValue new_src)
 
       auto& srcs = m_slots[slot]->sources();
 
-      PVirtualValue test_src[3];
-      std::transform(srcs.begin(), srcs.end(), test_src,
+      std::array<PVirtualValue, 3> test_src;
+      std::transform(srcs.begin(),
+                     srcs.end(),
+                     test_src.begin(),
                      [old_src, new_src](PVirtualValue s) {
-         return old_src->equal_to(*s) ? new_src : s;
-      });
+                        return old_src->equal_to(*s) ? new_src : s;
+                     });
 
       AluBankSwizzle bs = alu_vec_012;
       while (bs != alu_vec_unknown) {
          AluReadportReservation rpr = rpr_sum;
-         if (rpr.schedule_vec_src(test_src,srcs.size(), bs)) {
+         unsigned nsrc = srcs.size();
+         if (rpr.schedule_vec_src(test_src, nsrc, bs) == nsrc) {
             rpr_sum = rpr;
             break;
          }