r600/sfn: copy-propagate single source texture values

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18619>

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

@@ -357,6 +357,28 @@ bool TexInstr::from_nir(nir_tex_instr *tex, Shader& shader)
    return true;
 }
 
+bool TexInstr::replace_source(PRegister old_src, PVirtualValue new_src)
+{
+   if (old_src->pin() != pin_free)
+      return false;
+
+   if (!new_src->as_register())
+      return false;
+
+   bool success = false;
+   for (int i = 0; i < 4; ++i) {
+      if (m_src[i]->equal_to(*old_src)) {
+         m_src.set_value(i, new_src->as_register());
+         success = true;
+      }
+   }
+   if (success) {
+      old_src->del_use(this);
+      new_src->as_register()->add_use(this);
+   }
+   return success;
+}
+
 struct SamplerId {
    int id;
    bool indirect;

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

@@ -154,6 +154,8 @@ public:
 
    auto prepare_instr() const { return m_prepare_instr;}
 
+   bool replace_source(PRegister old_src, PVirtualValue new_src) override;
+
 private:
 
    bool do_ready() const override;

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

@@ -522,7 +522,20 @@ void SimplifySourceVecVisitor::visit(TexInstr *instr)
 {
 
    if (instr->opcode() != TexInstr::get_resinfo) {
-      replace_src(instr, instr->src());
+      auto& src = instr->src();
+      replace_src(instr, src);
+      int nvals = 0;
+      for (int i = 0; i < 4; ++i)
+         if (src[i]->chan() < 4)
+            ++nvals;
+      if (nvals == 1) {
+         for (int i = 0; i < 4; ++i)
+            if (src[i]->chan() < 4)
+               src[i]->set_pin(pin_free);
+      }
+   }
+   for (auto& prep : instr->prepare_instr()) {
+      prep->accept(*this);
    }
 }
 

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

@@ -272,21 +272,27 @@ public:
            return m_values[i]->value();
 	}
 
-        PRegister operator [] (int i) {
+   PRegister operator [] (int i) {
-           return m_values[i]->value();
+      return m_values[i]->value();
-        }
+   }
 
-        void set_value(int i, PRegister reg) {
+   void set_value(int i, PRegister reg) {
-           assert(reg->sel() == m_sel);
+      if (reg->chan() < 4) {
-           m_swz[i] = reg->chan();
+         for (int k = 0; k < 4; ++k) {
-           m_values[i]->set_value(reg);
+            assert(i == k || m_values[k]->value()->chan() > 3 ||
-        }
+                   m_values[k]->value()->sel() == reg->sel());
+         }
+         m_sel = reg->sel();
+      }
+      m_swz[i] = reg->chan();
+      m_values[i]->set_value(reg);
+   }
 
-        bool ready(int block_id, int index) const;
+   bool ready(int block_id, int index) const;
 private:
-        int m_sel;
+   int m_sel;
-        Swizzle m_swz;
+   Swizzle m_swz;
-        std::array<R600_POINTER_TYPE(Element), 4> m_values;
+   std::array<R600_POINTER_TYPE(Element), 4> m_values;
 };
 
 bool operator == (const RegisterVec4& lhs, const RegisterVec4& rhs);