ir_to_mesa: Add support for variable indexing of temporary arrays.

Fixes loop-01.vert, loop-02.vert.

ir_to_mesa.cpp

@@ -51,7 +51,7 @@ extern "C" {
 }
 
 ir_to_mesa_src_reg ir_to_mesa_undef = {
-   PROGRAM_UNDEFINED, 0, SWIZZLE_NOOP
+   PROGRAM_UNDEFINED, 0, SWIZZLE_NOOP, false,
 };
 
 ir_to_mesa_dst_reg ir_to_mesa_undef_dst = {
@@ -659,13 +659,11 @@ ir_to_mesa_visitor::visit(ir_dereference_array *ir)
     */
    assert(!var->type->is_matrix());
 
-   tree = this->create_tree(MB_TERM_reference_vec4, ir, NULL, NULL);
-
    if (strncmp(var->name, "gl_", 3) == 0) {
       unsigned int i;
       unsigned int offset = 0;
 
-      assert(index); /* FINISHME: Handle variable indexing of builtins. */
+      tree = this->create_tree(MB_TERM_reference_vec4, ir, NULL, NULL);
 
       offset = index->value.i[0];
 
@@ -677,11 +675,24 @@ ir_to_mesa_visitor::visit(ir_dereference_array *ir)
       ir_to_mesa_set_tree_reg(tree, builtin_var_to_mesa_reg[i].file,
 			      builtin_var_to_mesa_reg[i].index + offset);
    } else {
+      tree = this->create_tree(MB_TERM_reference_vec4, ir, NULL, NULL);
       this->get_temp_for_var(var, tree);
-      assert(index); /* FINISHME: Handle variable indexing. */
 
-      tree->src_reg.index += index->value.i[0];
-      tree->dst_reg.index += index->value.i[0];
+      if (index) {
+	 tree->src_reg.index += index->value.i[0];
+	 tree->dst_reg.index += index->value.i[0];
+      } else {
+	 /* Variable index array dereference.  It eats the "vec4" of the
+	  * base of the array and an index that offsets the Mesa register
+	  * index.
+	  */
+	 ir->array_index->accept(this);
+
+	 tree->src_reg.reladdr = true;
+	 tree = this->create_tree(MB_TERM_array_reference_vec4_vec4,
+				  ir, tree, this->result);
+	 this->get_temp(tree, ir->type->vector_elements);
+      }
    }
 
    /* If the type is smaller than a vec4, replicate the last channel out. */
@@ -841,6 +852,7 @@ mesa_src_reg_from_ir_src_reg(ir_to_mesa_src_reg reg)
    assert(reg.index < (1 << INST_INDEX_BITS) - 1);
    mesa_reg.Index = reg.index;
    mesa_reg.Swizzle = reg.swizzle;
+   mesa_reg.RelAddr = reg.reladdr;
 
    return mesa_reg;
 }

ir_to_mesa.h

@@ -40,6 +40,7 @@ typedef struct ir_to_mesa_src_reg {
    int file; /**< PROGRAM_* from Mesa */
    int index; /**< temporary index, VERT_ATTRIB_*, FRAG_ATTRIB_*, etc. */
    int swizzle; /**< SWIZZLE_XYZWONEZERO swizzles from Mesa. */
+   bool reladdr; /**< Register index should be offset by address reg. */
 } ir_to_mesa_src_reg;
 
 typedef struct ir_to_mesa_dst_reg {
@@ -145,6 +146,9 @@ public:
    exec_list instructions;
 };
 
+extern ir_to_mesa_src_reg ir_to_mesa_undef;
+extern ir_to_mesa_dst_reg ir_to_mesa_undef_dst;
+
 ir_to_mesa_instruction *
 ir_to_mesa_emit_op1(struct mbtree *tree, enum prog_opcode op);
 

mesa_codegen.brg

@@ -48,6 +48,7 @@
 # generate in its trees.
 %term assign
 %term reference_vec4
+%term array_reference_vec4_vec4
 %term exp_vec4
 %term exp2_vec4
 %term log_vec4
@@ -93,6 +94,20 @@
 # so it can be used as an argument for pretty much anything.
 vec4: reference_vec4 0
 
+# A reference of a variable is just a vec4 register location,
+# so it can be used as an argument for pretty much anything.
+vec4: array_reference_vec4_vec4 1
+{
+	ir_to_mesa_dst_reg address_reg = {PROGRAM_ADDRESS, 0, WRITEMASK_X};
+
+	ir_to_mesa_emit_op1_full(tree->v, tree->ir, OPCODE_ARL,
+				 address_reg,
+				 tree->right->src_reg);
+	ir_to_mesa_emit_op1_full(tree->v, tree->ir, OPCODE_MOV,
+				 tree->dst_reg,
+				 tree->left->src_reg);
+}
+
 # Here's the rule everyone will hit: Moving the result of an
 # expression into a variable-dereference register location.
 #