glsl: pull mark_array_elements_referenced() out into common helper

We will reuse this helper in the NIR linker in the following
patches.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4623>

src/compiler/glsl/ir_array_refcount.cpp

@@ -75,54 +75,6 @@ ir_array_refcount_entry::~ir_array_refcount_entry()
    delete [] bits;
 }
 
-
-void
-ir_array_refcount_entry::mark_array_elements_referenced(const array_deref_range *dr,
-                                                        unsigned count)
-{
-   if (count != array_depth)
-      return;
-
-   mark_array_elements_referenced(dr, count, 1, 0);
-}
-
-void
-ir_array_refcount_entry::mark_array_elements_referenced(const array_deref_range *dr,
-                                                        unsigned count,
-                                                        unsigned scale,
-                                                        unsigned linearized_index)
-{
-   /* Walk through the list of array dereferences in least- to
-    * most-significant order.  Along the way, accumulate the current
-    * linearized offset and the scale factor for each array-of-.
-    */
-   for (unsigned i = 0; i < count; i++) {
-      if (dr[i].index < dr[i].size) {
-         linearized_index += dr[i].index * scale;
-         scale *= dr[i].size;
-      } else {
-         /* For each element in the current array, update the count and
-          * offset, then recurse to process the remaining arrays.
-          *
-          * There is some inefficency here if the last element in the
-          * array_deref_range list specifies the entire array.  In that case,
-          * the loop will make recursive calls with count == 0.  In the call,
-          * all that will happen is the bit will be set.
-          */
-         for (unsigned j = 0; j < dr[i].size; j++) {
-            mark_array_elements_referenced(&dr[i + 1],
-                                           count - (i + 1),
-                                           scale * dr[i].size,
-                                           linearized_index + (j * scale));
-         }
-
-         return;
-      }
-   }
-
-   BITSET_SET(bits, linearized_index);
-}
-
 ir_array_refcount_entry *
 ir_array_refcount_visitor::get_variable_entry(ir_variable *var)
 {
@@ -224,7 +176,9 @@ ir_array_refcount_visitor::visit_enter(ir_dereference_array *ir)
    if (entry == NULL)
       return visit_stop;
 
-   entry->mark_array_elements_referenced(derefs, num_derefs);
+   link_util_mark_array_elements_referenced(derefs, num_derefs,
+                                            entry->array_depth,
+                                            entry->bits);
 
    return visit_continue;
 }

src/compiler/glsl/ir_array_refcount.h

@@ -32,26 +32,10 @@
 
 #include "ir.h"
 #include "ir_visitor.h"
+#include "linker_util.h"
 #include "compiler/glsl_types.h"
 #include "util/bitset.h"
 
-/**
- * Describes an access of an array element or an access of the whole array
- */
-struct array_deref_range {
-   /**
-    * Index that was accessed.
-    *
-    * All valid array indices are less than the size of the array.  If index
-    * is equal to the size of the array, this means the entire array has been
-    * accessed (e.g., due to use of a non-constant index).
-    */
-   unsigned index;
-
-   /** Size of the array.  Used for offset calculations. */
-   unsigned size;
-};
-
 class ir_array_refcount_entry
 {
 public:
@@ -63,33 +47,11 @@ public:
    /** Has the variable been referenced? */
    bool is_referenced;
 
-   /**
+   /** Count of nested arrays in the type. */
-    * Mark a set of array elements as accessed.
+   unsigned array_depth;
-    *
+
-    * If every \c array_deref_range is for a single index, only a single
+   /** Set of bit-flags to note which array elements have been accessed. */
-    * element will be marked.  If any \c array_deref_range is for an entire
+   BITSET_WORD *bits;
-    * array-of-, then multiple elements will be marked.
-    *
-    * Items in the \c array_deref_range list appear in least- to
-    * most-significant order.  This is the \b opposite order the indices
-    * appear in the GLSL shader text.  An array access like
-    *
-    *     x = y[1][i][3];
-    *
-    * would appear as
-    *
-    *     { { 3, n }, { m, m }, { 1, p } }
-    *
-    * where n, m, and p are the sizes of the arrays-of-arrays.
-    *
-    * The set of marked array elements can later be queried by
-    * \c ::is_linearized_index_referenced.
-    *
-    * \param dr     List of array_deref_range elements to be processed.
-    * \param count  Number of array_deref_range elements to be processed.
-    */
-   void mark_array_elements_referenced(const array_deref_range *dr,
-                                       unsigned count);
 
    /** Has a linearized array index been referenced? */
    bool is_linearized_index_referenced(unsigned linearized_index) const
@@ -101,8 +63,6 @@ public:
    }
 
 private:
-   /** Set of bit-flags to note which array elements have been accessed. */
-   BITSET_WORD *bits;
 
    /**
     * Total number of bits referenced by \c bits.
@@ -111,27 +71,6 @@ private:
     */
    unsigned num_bits;
 
-   /** Count of nested arrays in the type. */
-   unsigned array_depth;
-
-   /**
-    * Recursive part of the public mark_array_elements_referenced method.
-    *
-    * The recursion occurs when an entire array-of- is accessed.  See the
-    * implementation for more details.
-    *
-    * \param dr                List of array_deref_range elements to be
-    *                          processed.
-    * \param count             Number of array_deref_range elements to be
-    *                          processed.
-    * \param scale             Current offset scale.
-    * \param linearized_index  Current accumulated linearized array index.
-    */
-   void mark_array_elements_referenced(const array_deref_range *dr,
-                                       unsigned count,
-                                       unsigned scale,
-                                       unsigned linearized_index);
-
    friend class array_refcount_test;
 };
 

src/compiler/glsl/linker_util.cpp

@@ -287,3 +287,90 @@ link_util_calculate_subroutine_compat(struct gl_shader_program *prog)
       }
    }
 }
+
+/**
+ * Recursive part of the public mark_array_elements_referenced function.
+ *
+ * The recursion occurs when an entire array-of- is accessed.  See the
+ * implementation for more details.
+ *
+ * \param dr                List of array_deref_range elements to be
+ *                          processed.
+ * \param count             Number of array_deref_range elements to be
+ *                          processed.
+ * \param scale             Current offset scale.
+ * \param linearized_index  Current accumulated linearized array index.
+ */
+void
+_mark_array_elements_referenced(const struct array_deref_range *dr,
+                                unsigned count, unsigned scale,
+                                unsigned linearized_index,
+                                BITSET_WORD *bits)
+{
+   /* Walk through the list of array dereferences in least- to
+    * most-significant order.  Along the way, accumulate the current
+    * linearized offset and the scale factor for each array-of-.
+    */
+   for (unsigned i = 0; i < count; i++) {
+      if (dr[i].index < dr[i].size) {
+         linearized_index += dr[i].index * scale;
+         scale *= dr[i].size;
+      } else {
+         /* For each element in the current array, update the count and
+          * offset, then recurse to process the remaining arrays.
+          *
+          * There is some inefficency here if the last eBITSET_WORD *bitslement in the
+          * array_deref_range list specifies the entire array.  In that case,
+          * the loop will make recursive calls with count == 0.  In the call,
+          * all that will happen is the bit will be set.
+          */
+         for (unsigned j = 0; j < dr[i].size; j++) {
+            _mark_array_elements_referenced(&dr[i + 1],
+                                            count - (i + 1),
+                                            scale * dr[i].size,
+                                            linearized_index + (j * scale),
+                                            bits);
+         }
+
+         return;
+      }
+   }
+
+   BITSET_SET(bits, linearized_index);
+}
+
+/**
+ * Mark a set of array elements as accessed.
+ *
+ * If every \c array_deref_range is for a single index, only a single
+ * element will be marked.  If any \c array_deref_range is for an entire
+ * array-of-, then multiple elements will be marked.
+ *
+ * Items in the \c array_deref_range list appear in least- to
+ * most-significant order.  This is the \b opposite order the indices
+ * appear in the GLSL shader text.  An array access like
+ *
+ *     x = y[1][i][3];
+ *
+ * would appear as
+ *
+ *     { { 3, n }, { m, m }, { 1, p } }
+ *
+ * where n, m, and p are the sizes of the arrays-of-arrays.
+ *
+ * The set of marked array elements can later be queried by
+ * \c ::is_linearized_index_referenced.
+ *
+ * \param dr     List of array_deref_range elements to be processed.
+ * \param count  Number of array_deref_range elements to be processed.
+ */
+void
+link_util_mark_array_elements_referenced(const struct array_deref_range *dr,
+                                         unsigned count, unsigned array_depth,
+                                         BITSET_WORD *bits)
+{
+   if (count != array_depth)
+      return;
+
+   _mark_array_elements_referenced(dr, count, 1, 0, bits);
+}

src/compiler/glsl/linker_util.h

@@ -24,6 +24,8 @@
 #ifndef GLSL_LINKER_UTIL_H
 #define GLSL_LINKER_UTIL_H
 
+#include "util/bitset.h"
+
 struct gl_context;
 struct gl_shader_program;
 struct gl_uniform_storage;
@@ -45,6 +47,23 @@ struct empty_uniform_block {
    unsigned slots;
 };
 
+/**
+ * Describes an access of an array element or an access of the whole array
+ */
+struct array_deref_range {
+   /**
+    * Index that was accessed.
+    *
+    * All valid array indices are less than the size of the array.  If index
+    * is equal to the size of the array, this means the entire array has been
+    * accessed (e.g., due to use of a non-constant index).
+    */
+   unsigned index;
+
+   /** Size of the array.  Used for offset calculations. */
+   unsigned size;
+};
+
 void
 linker_error(struct gl_shader_program *prog, const char *fmt, ...);
 
@@ -81,6 +100,11 @@ link_util_check_uniform_resources(struct gl_context *ctx,
 void
 link_util_calculate_subroutine_compat(struct gl_shader_program *prog);
 
+void
+link_util_mark_array_elements_referenced(const struct array_deref_range *dr,
+                                         unsigned count, unsigned array_depth,
+                                         BITSET_WORD *bits);
+
 #ifdef __cplusplus
 }
 #endif

src/compiler/glsl/tests/array_refcount_test.cpp

@@ -283,7 +283,8 @@ TEST_F(array_refcount_test, mark_array_elements_referenced_simple)
    };
    const unsigned accessed_element = 0 + (1 * 5) + (2 * 4 * 5);
 
-   entry.mark_array_elements_referenced(dr, 3);
+   link_util_mark_array_elements_referenced(dr, 3, entry.array_depth,
+                                            entry.bits);
 
    for (unsigned i = 0; i < total_elements; i++)
       EXPECT_EQ(i == accessed_element, entry.is_linearized_index_referenced(i));
@@ -302,7 +303,8 @@ TEST_F(array_refcount_test, mark_array_elements_referenced_whole_first_array)
       { 0, 5 }, { 1, 4 }, { 3, 3 }
    };
 
-   entry.mark_array_elements_referenced(dr, 3);
+   link_util_mark_array_elements_referenced(dr, 3, entry.array_depth,
+                                            entry.bits);
 
    for (unsigned i = 0; i < 3; i++) {
       for (unsigned j = 0; j < 4; j++) {
@@ -330,7 +332,8 @@ TEST_F(array_refcount_test, mark_array_elements_referenced_whole_second_array)
       { 0, 5 }, { 4, 4 }, { 1, 3 }
    };
 
-   entry.mark_array_elements_referenced(dr, 3);
+   link_util_mark_array_elements_referenced(dr, 3, entry.array_depth,
+                                            entry.bits);
 
    for (unsigned i = 0; i < 3; i++) {
       for (unsigned j = 0; j < 4; j++) {
@@ -358,7 +361,8 @@ TEST_F(array_refcount_test, mark_array_elements_referenced_whole_third_array)
       { 5, 5 }, { 2, 4 }, { 1, 3 }
    };
 
-   entry.mark_array_elements_referenced(dr, 3);
+   link_util_mark_array_elements_referenced(dr, 3, entry.array_depth,
+                                            entry.bits);
 
    for (unsigned i = 0; i < 3; i++) {
       for (unsigned j = 0; j < 4; j++) {
@@ -386,7 +390,8 @@ TEST_F(array_refcount_test, mark_array_elements_referenced_whole_first_and_third
       { 5, 5 }, { 3, 4 }, { 3, 3 }
    };
 
-   entry.mark_array_elements_referenced(dr, 3);
+   link_util_mark_array_elements_referenced(dr, 3, entry.array_depth,
+                                            entry.bits);
 
    for (unsigned i = 0; i < 3; i++) {
       for (unsigned j = 0; j < 4; j++) {