[Mesa-dev] [PATCH v3] glsl: Expand matrix flip optimization pass to cover more cases.

[Iago Toral Quiroga]

Also, as suggested by Ian Romanick, make it so we don't need a bunch of
individual handles to flippable matrices, instead we register
matrix/transpose_matrix pairs in a hash table for all built-in matrices
using the non-transpose matrix name as key.
---

I was wondering, is it really safe to only dup the variable name in the case
that transpose_ptr != NULL? What if the variable gets killed in other
optimization passes? we would have garbage keys in the hash table... wouldn't
that cause problems?

 src/glsl/opt_flip_matrices.cpp | 153 +++++++++++++++++++++++++++++++----------
 1 file changed, 117 insertions(+), 36 deletions(-)

diff --git a/src/glsl/opt_flip_matrices.cpp b/src/glsl/opt_flip_matrices.cpp
index 9044fd6..80ecb0d 100644
--- a/src/glsl/opt_flip_matrices.cpp
+++ b/src/glsl/opt_flip_matrices.cpp
@@ -29,44 +29,142 @@
  * On some hardware, this is more efficient.
  *
  * This currently only does the conversion for built-in matrices which
- * already have transposed equivalents.  Namely, gl_ModelViewProjectionMatrix
- * and gl_TextureMatrix.
+ * already have transposed equivalents.
  */
 #include "ir.h"
 #include "ir_optimization.h"
 #include "main/macros.h"
+#include "program/hash_table.h"
 
 namespace {
+
 class matrix_flipper : public ir_hierarchical_visitor {
 public:
+   struct matrix_and_transpose {
+      ir_variable *matrix;
+      ir_variable *transpose_matrix;
+   };
+
    matrix_flipper(exec_list *instructions)
    {
       progress = false;
-      mvp_transpose = NULL;
-      texmat_transpose = NULL;
+
+      /* Build a hash table of built-in matrices and their transposes.
+       *
+       * The key for the entries in the hash table is the non-transpose matrix
+       * name. This assumes that all built-in transpose matrices have the
+       * "Transpose" suffix.
+       */
+      ht = hash_table_ctor(0, hash_table_string_hash,
+                           hash_table_string_compare);
 
       foreach_list(n, instructions) {
          ir_instruction *ir = (ir_instruction *) n;
          ir_variable *var = ir->as_variable();
+
          if (!var)
             continue;
-         if (strcmp(var->name, "gl_ModelViewProjectionMatrixTranspose") == 0)
-            mvp_transpose = var;
-         if (strcmp(var->name, "gl_TextureMatrixTranspose") == 0)
-            texmat_transpose = var;
+
+         /* Must be a matrix or array of matrices. */
+         if (!var->type->is_matrix() &&
+             !(var->type->is_array() && var->type->fields.array->is_matrix()))
+            continue;
+
+         /* Must be a built-in */
+         if (is_gl_identifier(var->name))
+            continue;
+
+         /* Create a new entry for this matrix if we don't have one yet */
+         bool new_entry = false;
+         struct matrix_and_transpose *entry =
+            (struct matrix_and_transpose *) hash_table_find(ht, var->name);
+         if (!entry) {
+            new_entry = true;
+            entry = new struct matrix_and_transpose();
+            entry->matrix = NULL;
+            entry->transpose_matrix = NULL;
+         }
+
+         const char *transpose_ptr = strstr(var->name, "Transpose");
+         if (transpose_ptr == NULL) {
+            entry->matrix = var;
+         } else {
+            /* We should not be adding transpose built-in matrices that do
+             * not end in 'Transpose'.
+             */
+            assert(transpose_ptr[9] == 0);
+            entry->transpose_matrix = var;
+         }
+
+         if (new_entry) {
+            char *entry_key;
+            if (transpose_ptr == NULL) {
+               entry_key = (char *) var->name;
+            } else {
+               entry_key =
+                  ralloc_strndup(this, var->name, transpose_ptr - var->name);
+            }
+            hash_table_insert(ht, entry, entry_key);
+         }
       }
    }
 
+   ~matrix_flipper()
+   {
+      hash_table_dtor(ht);
+   }
+
    ir_visitor_status visit_enter(ir_expression *ir);
 
    bool progress;
 
 private:
-   ir_variable *mvp_transpose;
-   ir_variable *texmat_transpose;
+   void transform_operands(ir_expression *ir,
+                           ir_variable *mat_var,
+                           ir_variable *mat_transpose);
+   void transform_operands_array_of_matrix(ir_expression *ir,
+                                           ir_variable *mat_var,
+                                           ir_variable *mat_transpose);
+   struct hash_table *ht;
 };
 }
 
+void
+matrix_flipper::transform_operands(ir_expression *ir,
+                                   ir_variable *mat_var,
+                                   ir_variable *mat_transpose)
+{
+#ifndef NDEBUG
+   ir_dereference_variable *deref = ir->operands[0]->as_dereference_variable();
+   assert(deref && deref->var == mat_var);
+#endif
+
+   void *mem_ctx = ralloc_parent(ir);
+   ir->operands[0] = ir->operands[1];
+   ir->operands[1] = new(mem_ctx) ir_dereference_variable(mat_transpose);
+}
+
+void
+matrix_flipper::transform_operands_array_of_matrix(ir_expression *ir,
+                                                   ir_variable *mat_var,
+                                                   ir_variable *mat_transpose)
+{
+   ir_dereference_array *array_ref = ir->operands[0]->as_dereference_array();
+   assert(array_ref != NULL);
+   ir_dereference_variable *var_ref =
+      array_ref->array->as_dereference_variable();
+   assert(var_ref && var_ref->var == mat_var);
+
+   ir->operands[0] = ir->operands[1];
+   ir->operands[1] = array_ref;
+
+   var_ref->var = mat_transpose;
+
+   mat_transpose->data.max_array_access =
+      MAX2(mat_transpose->data.max_array_access,
+           mat_var->data.max_array_access);
+}
+
 ir_visitor_status
 matrix_flipper::visit_enter(ir_expression *ir)
 {
@@ -79,34 +177,17 @@ matrix_flipper::visit_enter(ir_expression *ir)
    if (!mat_var)
       return visit_continue;
 
-   if (mvp_transpose &&
-       strcmp(mat_var->name, "gl_ModelViewProjectionMatrix") == 0) {
-#ifndef NDEBUG
-      ir_dereference_variable *deref = ir->operands[0]->as_dereference_variable();
-      assert(deref && deref->var == mat_var);
-#endif
-
-      void *mem_ctx = ralloc_parent(ir);
-
-      ir->operands[0] = ir->operands[1];
-      ir->operands[1] = new(mem_ctx) ir_dereference_variable(mvp_transpose);
+   struct matrix_and_transpose *entry =
+      (struct matrix_and_transpose *) hash_table_find(ht, mat_var->name);
+   if (!entry || !entry->transpose_matrix)
+      return visit_continue;
 
+   if (strcmp(mat_var->name, "gl_TextureMatrix") == 0 ||
+       strcmp(mat_var->name, "gl_TextureMatrixInverse") == 0) {
+      transform_operands_array_of_matrix(ir, mat_var, entry->transpose_matrix);
       progress = true;
-   } else if (texmat_transpose &&
-              strcmp(mat_var->name, "gl_TextureMatrix") == 0) {
-      ir_dereference_array *array_ref = ir->operands[0]->as_dereference_array();
-      assert(array_ref != NULL);
-      ir_dereference_variable *var_ref = array_ref->array->as_dereference_variable();
-      assert(var_ref && var_ref->var == mat_var);
-
-      ir->operands[0] = ir->operands[1];
-      ir->operands[1] = array_ref;
-
-      var_ref->var = texmat_transpose;
-
-      texmat_transpose->data.max_array_access =
-         MAX2(texmat_transpose->data.max_array_access, mat_var->data.max_array_access);
-
+   } else {
+      transform_operands(ir, mat_var, entry->transpose_matrix);
       progress = true;
    }
 
-- 
1.9.1