i965: Prevent implicit upcasts to brw_reg.

Now that backend_reg inherits from brw_reg, we have to be careful to
avoid the object slicing problem.

Reviewed-by: Francisco Jerez <currojerez@riseup.net>

src/mesa/drivers/dri/i965/brw_fs.cpp

@@ -2037,7 +2037,8 @@ fs_visitor::opt_algebraic()
             if (inst->dst.type != inst->src[0].type)
                assert(!"unimplemented: saturate mixed types");
 
-            if (brw_saturate_immediate(inst->dst.type, &inst->src[0])) {
+            if (brw_saturate_immediate(inst->dst.type,
+                                       &inst->src[0].as_brw_reg())) {
                inst->saturate = false;
                progress = true;
             }

src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp

@@ -532,14 +532,14 @@ fs_visitor::try_constant_propagate(fs_inst *inst, acp_entry *entry)
 
       if (inst->src[i].abs) {
          if ((devinfo->gen >= 8 && is_logic_op(inst->opcode)) ||
-             !brw_abs_immediate(val.type, &val)) {
+             !brw_abs_immediate(val.type, &val.as_brw_reg())) {
             continue;
          }
       }
 
       if (inst->src[i].negate) {
          if ((devinfo->gen >= 8 && is_logic_op(inst->opcode)) ||
-             !brw_negate_immediate(val.type, &val)) {
+             !brw_negate_immediate(val.type, &val.as_brw_reg())) {
             continue;
          }
       }

src/mesa/drivers/dri/i965/brw_fs_generator.cpp

@@ -92,7 +92,7 @@ brw_reg_from_fs_reg(fs_inst *inst, fs_reg *reg, unsigned gen)
    case ARF:
    case FIXED_GRF:
    case IMM:
-      brw_reg = *static_cast<struct brw_reg *>(reg);
+      brw_reg = reg->as_brw_reg();
       break;
    case BAD_FILE:
       /* Probably unused. */

src/mesa/drivers/dri/i965/brw_shader.h

@@ -39,11 +39,25 @@
 #define MAX_VGRF_SIZE 16
 
 #ifdef __cplusplus
-struct backend_reg : public brw_reg
+struct backend_reg : private brw_reg
 {
    backend_reg() {}
    backend_reg(const struct brw_reg &reg) : brw_reg(reg) {}
 
+   const brw_reg &as_brw_reg() const
+   {
+      assert(file == ARF || file == FIXED_GRF || file == MRF || file == IMM);
+      assert(reg_offset == 0);
+      return static_cast<const brw_reg &>(*this);
+   }
+
+   brw_reg &as_brw_reg()
+   {
+      assert(file == ARF || file == FIXED_GRF || file == MRF || file == IMM);
+      assert(reg_offset == 0);
+      return static_cast<brw_reg &>(*this);
+   }
+
    bool equals(const backend_reg &r) const;
 
    bool is_zero() const;
@@ -63,6 +77,25 @@ struct backend_reg : public brw_reg
     * For uniforms, this is in units of 1 float.
     */
    uint16_t reg_offset;
+
+   using brw_reg::type;
+   using brw_reg::file;
+   using brw_reg::negate;
+   using brw_reg::abs;
+   using brw_reg::address_mode;
+   using brw_reg::subnr;
+   using brw_reg::nr;
+
+   using brw_reg::swizzle;
+   using brw_reg::writemask;
+   using brw_reg::indirect_offset;
+   using brw_reg::vstride;
+   using brw_reg::width;
+   using brw_reg::hstride;
+
+   using brw_reg::f;
+   using brw_reg::d;
+   using brw_reg::ud;
 };
 #endif
 

src/mesa/drivers/dri/i965/brw_vec4.cpp

@@ -583,7 +583,8 @@ vec4_visitor::opt_algebraic()
             if (inst->dst.type != inst->src[0].type)
                assert(!"unimplemented: saturate mixed types");
 
-            if (brw_saturate_immediate(inst->dst.type, &inst->src[0])) {
+            if (brw_saturate_immediate(inst->dst.type,
+                                       &inst->src[0].as_brw_reg())) {
                inst->saturate = false;
                progress = true;
             }
@@ -1765,7 +1766,7 @@ vec4_visitor::convert_to_hw_regs()
 
       case ARF:
       case FIXED_GRF:
-         reg = dst;
+         reg = dst.as_brw_reg();
          break;
 
       case BAD_FILE:

src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp

@@ -134,14 +134,14 @@ try_constant_propagate(const struct brw_device_info *devinfo,
 
    if (inst->src[arg].abs) {
       if ((devinfo->gen >= 8 && is_logic_op(inst->opcode)) ||
-          !brw_abs_immediate(value.type, &value)) {
+          !brw_abs_immediate(value.type, &value.as_brw_reg())) {
          return false;
       }
    }
 
    if (inst->src[arg].negate) {
       if ((devinfo->gen >= 8 && is_logic_op(inst->opcode)) ||
-          !brw_negate_immediate(value.type, &value)) {
+          !brw_negate_immediate(value.type, &value.as_brw_reg())) {
          return false;
       }
    }

src/mesa/drivers/dri/i965/brw_vec4_generator.cpp

@@ -356,7 +356,7 @@ generate_gs_urb_write_allocate(struct brw_codegen *p, vec4_instruction *inst)
 
    /* We pass the temporary passed in src0 as the writeback register */
    brw_urb_WRITE(p,
-                 inst->src[0], /* dest */
+                 inst->src[0].as_brw_reg(), /* dest */
                  inst->base_mrf, /* starting mrf reg nr */
                  src,
                  BRW_URB_WRITE_ALLOCATE_COMPLETE,
@@ -369,8 +369,8 @@ generate_gs_urb_write_allocate(struct brw_codegen *p, vec4_instruction *inst)
    brw_push_insn_state(p);
    brw_set_default_access_mode(p, BRW_ALIGN_1);
    brw_set_default_mask_control(p, BRW_MASK_DISABLE);
-   brw_MOV(p, get_element_ud(inst->dst, 0),
-           get_element_ud(inst->src[0], 0));
+   brw_MOV(p, get_element_ud(inst->dst.as_brw_reg(), 0),
+           get_element_ud(inst->src[0].as_brw_reg(), 0));
    brw_pop_insn_state(p);
 }
 
@@ -1059,9 +1059,9 @@ generate_code(struct brw_codegen *p,
          annotate(p->devinfo, &annotation, cfg, inst, p->next_insn_offset);
 
       for (unsigned int i = 0; i < 3; i++) {
-         src[i] = inst->src[i];
+         src[i] = inst->src[i].as_brw_reg();
       }
-      dst = inst->dst;
+      dst = inst->dst.as_brw_reg();
 
       brw_set_default_predicate_control(p, inst->predicate);
       brw_set_default_predicate_inverse(p, inst->predicate_inverse);