[Mesa-dev] [PATCH] glsl: make a copy of array indices that are used to deref a function out param

[Timothy Arceri]

Fixes new piglit test:
tests/spec/glsl-1.20/execution/qualifiers/vs-out-conversion-int-to-float-vec4-index.shader_test
---
 src/compiler/glsl/ast_function.cpp | 94 ++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/src/compiler/glsl/ast_function.cpp b/src/compiler/glsl/ast_function.cpp
index 127aa1f91c4..97e78f99ea7 100644
--- a/src/compiler/glsl/ast_function.cpp
+++ b/src/compiler/glsl/ast_function.cpp
@@ -348,6 +348,93 @@ verify_parameter_modes(_mesa_glsl_parse_state *state,
    return true;
 }
 
+static void
+copy_index_derefs_to_temps(void *mem_ctx, ir_rvalue *param,
+                           exec_list *before_instructions)
+{
+   /* Loop through the IR copying array indices until we find a swizzle,
+    * costant or variable ref.
+    */
+   ir_rvalue *ir = param;
+   while (ir != NULL) {
+      switch (ir->ir_type) {
+      case ir_type_dereference_record: {
+         ir_dereference_record *r = (ir_dereference_record *) ir;
+         ir = r->record->as_dereference();
+         break;
+      }
+
+      case ir_type_swizzle: {
+         ir_swizzle *s = (ir_swizzle *) ir;
+         ir = s->val->as_dereference();
+         break;
+      }
+
+      case ir_type_expression: {
+         ir_expression *expr = (ir_expression* ) ir;
+         for (unsigned int i = 0; i < expr->num_operands; i++) {
+            copy_index_derefs_to_temps(mem_ctx, expr->operands[i],
+                                       before_instructions);
+         }
+
+         ir = NULL;
+         break;
+      }
+
+      case ir_type_dereference_array: {
+         ir_dereference_array *a = (ir_dereference_array *) ir;
+         ir = a->array->as_dereference();
+
+         ir_rvalue *idx = a->array_index;
+         copy_index_derefs_to_temps(mem_ctx, idx, before_instructions);
+
+         if (idx->as_dereference_variable()) {
+            ir_variable *var = idx->variable_referenced();
+
+            /* If the index is read only it cannot change so there is no need
+             * to copy it.
+             */
+            if (var->data.read_only || var->data.memory_read_only)
+               break;
+         }
+
+         ir_variable *tmp = new(mem_ctx) ir_variable(idx->type, "idx_tmp",
+                                                     ir_var_temporary);
+         before_instructions->push_tail(tmp);
+
+         ir_dereference_variable *const deref_tmp_1 =
+            new(mem_ctx) ir_dereference_variable(tmp);
+         ir_assignment *const assignment =
+            new(mem_ctx) ir_assignment(deref_tmp_1,
+                                       idx->clone(mem_ctx, NULL));
+         before_instructions->push_tail(assignment);
+
+         /* Replace the array index with a dereference of the new temporary.
+          */
+         ir_dereference_variable *const deref_tmp_2 =
+            new(mem_ctx) ir_dereference_variable(tmp);
+         a->array_index = deref_tmp_2;
+         break;
+      }
+
+      case ir_type_dereference_variable: {
+         ir = NULL;
+         break;
+      }
+
+      case ir_type_constant: {
+         /* Nothing to do for constants */
+         ir = NULL;
+         break;
+      }
+
+      default:
+         unreachable("Unexpected deref type");
+         break;
+      }
+   }
+}
+
 static void
 fix_parameter(void *mem_ctx, ir_rvalue *actual, const glsl_type *formal_type,
               exec_list *before_instructions, exec_list *after_instructions,
@@ -362,6 +449,13 @@ fix_parameter(void *mem_ctx, ir_rvalue *actual, const glsl_type *formal_type,
        && (expr == NULL || expr->operation != ir_binop_vector_extract))
       return;
 
+   /* An array index could also be an out variable so we need to make a copy
+    * of them before the function is called.
+    */
+   if (!actual->as_dereference_variable()) {
+      copy_index_derefs_to_temps(mem_ctx, actual, before_instructions);
+   }
+
    /* To convert an out parameter, we need to create a temporary variable to
     * hold the value before conversion, and then perform the conversion after
     * the function call returns.
-- 
2.17.1