+ir_rvalue::ir_rvalue()
+{
+ this->type = glsl_type::error_type;
+}
+
+bool ir_rvalue::is_zero() const
+{
+ return false;
+}
+
+bool ir_rvalue::is_one() const
+{
+ return false;
+}
+
+bool ir_rvalue::is_negative_one() const
+{
+ return false;
+}
+
+/**
+ * Modify the swizzle make to move one component to another
+ *
+ * \param m IR swizzle to be modified
+ * \param from Component in the RHS that is to be swizzled
+ * \param to Desired swizzle location of \c from
+ */
+static void
+update_rhs_swizzle(ir_swizzle_mask &m, unsigned from, unsigned to)
+{
+ switch (to) {
+ case 0: m.x = from; break;
+ case 1: m.y = from; break;
+ case 2: m.z = from; break;
+ case 3: m.w = from; break;
+ default: assert(!"Should not get here.");
+ }
+
+ m.num_components = MAX2(m.num_components, (to + 1));
+}
+
+void
+ir_assignment::set_lhs(ir_rvalue *lhs)
+{
+ void *mem_ctx = this;
+ bool swizzled = false;
+
+ while (lhs != NULL) {
+ ir_swizzle *swiz = lhs->as_swizzle();
+
+ if (swiz == NULL)
+ break;
+
+ unsigned write_mask = 0;
+ ir_swizzle_mask rhs_swiz = { 0, 0, 0, 0, 0, 0 };
+
+ for (unsigned i = 0; i < swiz->mask.num_components; i++) {
+ unsigned c = 0;
+
+ switch (i) {
+ case 0: c = swiz->mask.x; break;
+ case 1: c = swiz->mask.y; break;
+ case 2: c = swiz->mask.z; break;
+ case 3: c = swiz->mask.w; break;
+ default: assert(!"Should not get here.");
+ }
+
+ write_mask |= (((this->write_mask >> i) & 1) << c);
+ update_rhs_swizzle(rhs_swiz, i, c);
+ }
+
+ this->write_mask = write_mask;
+ lhs = swiz->val;
+
+ this->rhs = new(mem_ctx) ir_swizzle(this->rhs, rhs_swiz);
+ swizzled = true;
+ }
+
+ if (swizzled) {
+ /* Now, RHS channels line up with the LHS writemask. Collapse it
+ * to just the channels that will be written.
+ */
+ ir_swizzle_mask rhs_swiz = { 0, 0, 0, 0, 0, 0 };
+ int rhs_chan = 0;
+ for (int i = 0; i < 4; i++) {
+ if (write_mask & (1 << i))
+ update_rhs_swizzle(rhs_swiz, i, rhs_chan++);
+ }
+ this->rhs = new(mem_ctx) ir_swizzle(this->rhs, rhs_swiz);
+ }
+
+ assert((lhs == NULL) || lhs->as_dereference());
+
+ this->lhs = (ir_dereference *) lhs;
+}
+
+ir_variable *
+ir_assignment::whole_variable_written()
+{
+ ir_variable *v = this->lhs->whole_variable_referenced();
+
+ if (v == NULL)
+ return NULL;
+
+ if (v->type->is_scalar())
+ return v;
+
+ if (v->type->is_vector()) {
+ const unsigned mask = (1U << v->type->vector_elements) - 1;
+
+ if (mask != this->write_mask)
+ return NULL;
+ }
+
+ /* Either all the vector components are assigned or the variable is some
+ * composite type (and the whole thing is assigned.
+ */
+ return v;
+}
+
+ir_assignment::ir_assignment(ir_dereference *lhs, ir_rvalue *rhs,
+ ir_rvalue *condition, unsigned write_mask)
+{
+ this->ir_type = ir_type_assignment;
+ this->condition = condition;
+ this->rhs = rhs;
+ this->lhs = lhs;
+ this->write_mask = write_mask;
+
+ if (lhs->type->is_scalar() || lhs->type->is_vector()) {
+ int lhs_components = 0;
+ for (int i = 0; i < 4; i++) {
+ if (write_mask & (1 << i))
+ lhs_components++;
+ }
+
+ assert(lhs_components == this->rhs->type->vector_elements);
+ }
+}
+