slang_codegen.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

   { "float_cosine", IR_COS, 1, 1 },
   { "float_noise1", IR_NOISE1, 1, 1},
   { "float_noise2", IR_NOISE2, 1, 1},
   { "float_noise3", IR_NOISE3, 1, 1},
   { "float_noise4", IR_NOISE4, 1, 1},

   { NULL, IR_NOP, 0, 0 }
};


static slang_ir_node *
new_node3(slang_ir_opcode op,
          slang_ir_node *c0, slang_ir_node *c1, slang_ir_node *c2)
{
   slang_ir_node *n = (slang_ir_node *) _slang_alloc(sizeof(slang_ir_node));
   if (n) {
      n->Opcode = op;
      n->Children[0] = c0;
      n->Children[1] = c1;
      n->Children[2] = c2;
      n->Writemask = WRITEMASK_XYZW;
      n->InstLocation = -1;
   }
   return n;
}

static slang_ir_node *
new_node2(slang_ir_opcode op, slang_ir_node *c0, slang_ir_node *c1)
{
   return new_node3(op, c0, c1, NULL);
}

static slang_ir_node *
new_node1(slang_ir_opcode op, slang_ir_node *c0)
{
   return new_node3(op, c0, NULL, NULL);
}

static slang_ir_node *
new_node0(slang_ir_opcode op)
{
   return new_node3(op, NULL, NULL, NULL);
}


/**
 * Create sequence of two nodes.
 */
static slang_ir_node *
new_seq(slang_ir_node *left, slang_ir_node *right)
{
   if (!left)
      return right;
   if (!right)
      return left;
   return new_node2(IR_SEQ, left, right);
}

static slang_ir_node *
new_label(slang_label *label)
{
   slang_ir_node *n = new_node0(IR_LABEL);
   assert(label);
   if (n)
      n->Label = label;
   return n;
}

static slang_ir_node *
new_float_literal(const float v[4], GLuint size)
{
   slang_ir_node *n = new_node0(IR_FLOAT);
   assert(size <= 4);
   COPY_4V(n->Value, v);
   /* allocate a storage object, but compute actual location (Index) later */
   n->Store = _slang_new_ir_storage(PROGRAM_CONSTANT, -1, size);
   return n;
}


static slang_ir_node *
new_not(slang_ir_node *n)
{
   return new_node1(IR_NOT, n);
}


/**
 * Non-inlined function call.
 */
static slang_ir_node *
new_function_call(slang_ir_node *code, slang_label *name)
{
   slang_ir_node *n = new_node1(IR_CALL, code);
   assert(name);
   if (n)
      n->Label = name;
   return n;
}


/**
 * Unconditional jump.
 */
static slang_ir_node *
new_return(slang_label *dest)
{
   slang_ir_node *n = new_node0(IR_RETURN);
   assert(dest);
   if (n)
      n->Label = dest;
   return n;
}


static slang_ir_node *
new_loop(slang_ir_node *body)
{
   return new_node1(IR_LOOP, body);
}


static slang_ir_node *
new_break(slang_ir_node *loopNode)
{
   slang_ir_node *n = new_node0(IR_BREAK);
   assert(loopNode);
   assert(loopNode->Opcode == IR_LOOP);
   if (n) {
      /* insert this node at head of linked list */
      n->List = loopNode->List;
      loopNode->List = n;
   }
   return n;
}


/**
 * Make new IR_BREAK_IF_TRUE.
 */
static slang_ir_node *
new_break_if_true(slang_ir_node *loopNode, slang_ir_node *cond)
{
   slang_ir_node *n;
   assert(loopNode);
   assert(loopNode->Opcode == IR_LOOP);
   n = new_node1(IR_BREAK_IF_TRUE, cond);
   if (n) {
      /* insert this node at head of linked list */
      n->List = loopNode->List;
      loopNode->List = n;
   }
   return n;
}


/**
 * Make new IR_CONT_IF_TRUE node.
 */
static slang_ir_node *
new_cont_if_true(slang_ir_node *loopNode, slang_ir_node *cond)
{
   slang_ir_node *n;
   assert(loopNode);
   assert(loopNode->Opcode == IR_LOOP);
   n = new_node1(IR_CONT_IF_TRUE, cond);
   if (n) {
      /* insert this node at head of linked list */
      n->List = loopNode->List;
      loopNode->List = n;
   }
   return n;
}


static slang_ir_node *
new_cond(slang_ir_node *n)
{
   slang_ir_node *c = new_node1(IR_COND, n);
   return c;
}


static slang_ir_node *
new_if(slang_ir_node *cond, slang_ir_node *ifPart, slang_ir_node *elsePart)
{
   return new_node3(IR_IF, cond, ifPart, elsePart);
}


/**
 * New IR_VAR node - a reference to a previously declared variable.
 */
static slang_ir_node *
new_var(slang_assemble_ctx *A, slang_operation *oper, slang_atom name)
{
   slang_ir_node *n;
   slang_variable *var = _slang_locate_variable(oper->locals, name, GL_TRUE);
   if (!var)
      return NULL;

   assert(var->declared);

   assert(!oper->var || oper->var == var);

   n = new_node0(IR_VAR);
   if (n) {
      _slang_attach_storage(n, var);
      /*
      printf("new_var %s store=%p\n", (char*)name, (void*) n->Store);
      */
   }
   return n;
}


/**
 * Check if the given function is really just a wrapper for a
 * basic assembly instruction.
 */
static GLboolean
slang_is_asm_function(const slang_function *fun)
{
   if (fun->body->type == SLANG_OPER_BLOCK_NO_NEW_SCOPE &&
       fun->body->num_children == 1 &&
       fun->body->children[0].type == SLANG_OPER_ASM) {
      return GL_TRUE;
   }
   return GL_FALSE;
}


static GLboolean
_slang_is_noop(const slang_operation *oper)
{
   if (!oper ||
       oper->type == SLANG_OPER_VOID ||
       (oper->num_children == 1 && oper->children[0].type == SLANG_OPER_VOID))
      return GL_TRUE;
   else
      return GL_FALSE;
}


/**
 * Recursively search tree for a node of the given type.
 */
static slang_operation *
_slang_find_node_type(slang_operation *oper, slang_operation_type type)
{
   GLuint i;
   if (oper->type == type)
      return oper;
   for (i = 0; i < oper->num_children; i++) {
      slang_operation *p = _slang_find_node_type(&oper->children[i], type);
      if (p)
         return p;
   }
   return NULL;
}


/**
 * Count the number of operations of the given time rooted at 'oper'.
 */
static GLuint
_slang_count_node_type(slang_operation *oper, slang_operation_type type)
{
   GLuint i, count = 0;
   if (oper->type == type) {
      return 1;
   }
   for (i = 0; i < oper->num_children; i++) {
      count += _slang_count_node_type(&oper->children[i], type);
   }
   return count;
}


/**
 * Check if the 'return' statement found under 'oper' is a "tail return"
 * that can be no-op'd.  For example:
 *
 * void func(void)
 * {
 *    .. do something ..
 *    return;   // this is a no-op
 * }
 *
 * This is used when determining if a function can be inlined.  If the
 * 'return' is not the last statement, we can't inline the function since
 * we still need the semantic behaviour of the 'return' but we don't want
 * to accidentally return from the _calling_ function.  We'd need to use an
 * unconditional branch, but we don't have such a GPU instruction (not
 * always, at least).
 */
static GLboolean
_slang_is_tail_return(const slang_operation *oper)
{
   GLuint k = oper->num_children;

   while (k > 0) {
      const slang_operation *last = &oper->children[k - 1];
      if (last->type == SLANG_OPER_RETURN)
         return GL_TRUE;
      else if (last->type == SLANG_OPER_IDENTIFIER ||
               last->type == SLANG_OPER_LABEL)
         k--; /* try prev child */
      else if (last->type == SLANG_OPER_BLOCK_NO_NEW_SCOPE ||
               last->type == SLANG_OPER_BLOCK_NEW_SCOPE)
         /* try sub-children */
         return _slang_is_tail_return(last);
      else
         break;
   }

   return GL_FALSE;
}


static void
slang_resolve_variable(slang_operation *oper)
{
   if (oper->type == SLANG_OPER_IDENTIFIER && !oper->var) {
      oper->var = _slang_locate_variable(oper->locals, oper->a_id, GL_TRUE);
   }
}


/**
 * Replace particular variables (SLANG_OPER_IDENTIFIER) with new expressions.
 */
static void
slang_substitute(slang_assemble_ctx *A, slang_operation *oper,
                 GLuint substCount, slang_variable **substOld,
		 slang_operation **substNew, GLboolean isLHS)
{
   switch (oper->type) {
   case SLANG_OPER_VARIABLE_DECL:
      {
         slang_variable *v = _slang_locate_variable(oper->locals,
                                                    oper->a_id, GL_TRUE);
         assert(v);
         if (v->initializer && oper->num_children == 0) {
            /* set child of oper to copy of initializer */
            oper->num_children = 1;
            oper->children = slang_operation_new(1);
            slang_operation_copy(&oper->children[0], v->initializer);
         }
         if (oper->num_children == 1) {
            /* the initializer */
            slang_substitute(A, &oper->children[0], substCount,
                             substOld, substNew, GL_FALSE);
         }
      }
      break;
   case SLANG_OPER_IDENTIFIER:
      assert(oper->num_children == 0);
      if (1/**!isLHS XXX FIX */) {
         slang_atom id = oper->a_id;
         slang_variable *v;
	 GLuint i;
         v = _slang_locate_variable(oper->locals, id, GL_TRUE);
	 if (!v) {
            _mesa_problem(NULL, "var %s not found!\n", (char *) oper->a_id);
            return;
	 }

	 /* look for a substitution */
	 for (i = 0; i < substCount; i++) {
	    if (v == substOld[i]) {
               /* OK, replace this SLANG_OPER_IDENTIFIER with a new expr */
#if 0 /* DEBUG only */
	       if (substNew[i]->type == SLANG_OPER_IDENTIFIER) {
                  assert(substNew[i]->var);
                  assert(substNew[i]->var->a_name);
		  printf("Substitute %s with %s in id node %p\n",
			 (char*)v->a_name, (char*) substNew[i]->var->a_name,
			 (void*) oper);
               }
	       else {
		  printf("Substitute %s with %f in id node %p\n",
			 (char*)v->a_name, substNew[i]->literal[0],
			 (void*) oper);
               }
#endif
	       slang_operation_copy(oper, substNew[i]);
	       break;
	    }
	 }
      }
      break;

   case SLANG_OPER_RETURN:
      /* do return replacement here too */
      assert(oper->num_children == 0 || oper->num_children == 1);
      if (oper->num_children == 1 && !_slang_is_noop(&oper->children[0])) {
         /* replace:
          *   return expr;
          * with:
          *   __retVal = expr;
          *   return;
          * then do substitutions on the assignment.
          */
         slang_operation *blockOper, *assignOper, *returnOper;

         /* check if function actually has a return type */
         assert(A->CurFunction);
         if (A->CurFunction->header.type.specifier.type == SLANG_SPEC_VOID) {
            slang_info_log_error(A->log, "illegal return expression");
            return;
         }

         blockOper = slang_operation_new(1);
         blockOper->type = SLANG_OPER_BLOCK_NO_NEW_SCOPE;
         blockOper->num_children = 2;
         blockOper->locals->outer_scope = oper->locals->outer_scope;
         blockOper->children = slang_operation_new(2);
         assignOper = blockOper->children + 0;
         returnOper = blockOper->children + 1;

         assignOper->type = SLANG_OPER_ASSIGN;
         assignOper->num_children = 2;
         assignOper->locals->outer_scope = blockOper->locals;
         assignOper->children = slang_operation_new(2);
         assignOper->children[0].type = SLANG_OPER_IDENTIFIER;
         assignOper->children[0].a_id = slang_atom_pool_atom(A->atoms, "__retVal");
         assignOper->children[0].locals->outer_scope = assignOper->locals;

         slang_operation_copy(&assignOper->children[1],
                              &oper->children[0]);

         returnOper->type = SLANG_OPER_RETURN; /* return w/ no value */
         assert(returnOper->num_children == 0);

         /* do substitutions on the "__retVal = expr" sub-tree */
         slang_substitute(A, assignOper,
                          substCount, substOld, substNew, GL_FALSE);

         /* install new code */
         slang_operation_copy(oper, blockOper);
         slang_operation_destruct(blockOper);
      }
      else {
         /* check if return value was expected */
         assert(A->CurFunction);
         if (A->CurFunction->header.type.specifier.type != SLANG_SPEC_VOID) {
            slang_info_log_error(A->log, "return statement requires an expression");
            return;
         }
      }
      break;

   case SLANG_OPER_ASSIGN:
   case SLANG_OPER_SUBSCRIPT:
      /* special case:
       * child[0] can't have substitutions but child[1] can.
       */
      slang_substitute(A, &oper->children[0],