path: root/gcc/brig/brigfrontend/brig-function-handler.cc

/* brig-code-entry-handler.cc -- brig function directive handling
   Copyright (C) 2016-2021 Free Software Foundation, Inc.
   Contributed by Pekka Jaaskelainen <pekka.jaaskelainen@parmance.com>
   for General Processor Tech.

   This file is part of GCC.

   GCC is free software; you can redistribute it and/or modify it under
   the terms of the GNU General Public License as published by the Free
   Software Foundation; either version 3, or (at your option) any later
   version.

   GCC is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or
   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   for more details.

   You should have received a copy of the GNU General Public License
   along with GCC; see the file COPYING3.  If not see
   <http://www.gnu.org/licenses/>.  */

#include <sstream>
#include <iomanip>

#include "brig-code-entry-handler.h"

#include "brig-machine.h"
#include "stringpool.h"
#include "tree-iterator.h"
#include "gimple-expr.h"
#include "function.h"
#include "phsa.h"

#include "tree-pretty-print.h"
#include "print-tree.h"

extern int gccbrig_verbose;

size_t
brig_directive_function_handler::operator () (const BrigBase *base)
{
  if (!m_parent.m_analyzing)
    m_parent.finish_function ();

  size_t bytes_consumed = base->byteCount;

  const BrigDirectiveExecutable *exec = (const BrigDirectiveExecutable *) base;

  if (gccbrig_verbose)
    {
      printf ("brig: function name %s\n",
	      m_parent.get_string (exec->name).c_str());
      printf ("brig: inargs %d outargs %d name offset %d\n", exec->inArgCount,
	      exec->outArgCount, exec->name);
    }

  const bool is_definition
    = exec->modifier & BRIG_EXECUTABLE_DEFINITION;

  const bool is_kernel = base->kind == BRIG_KIND_DIRECTIVE_KERNEL;

  /* There doesn't seem to be actual use cases for kernel declarations
     as they cannot be called by the program.  Ignore them until there's
     a reason not to.  */
  if (is_kernel && !is_definition)
    return bytes_consumed;

  std::string func_name = m_parent.get_mangled_name (exec);
  if (is_kernel)
    /* The generated kernel function is not the one that should be
       called by the host.  */
    func_name = std::string ("_") + func_name;

  m_parent.m_cf = new brig_function (exec, &m_parent);
  m_parent.m_cf->m_name = func_name;
  m_parent.m_cf->m_is_kernel = is_kernel;

  /* During the analyze step, the above information is all we need per
     function.  */
  if (m_parent.m_analyzing)
    return bytes_consumed;

  /* There can be multiple forward declarations of the same function.
     Skip all but the first one.  */
  if (!is_definition && m_parent.function_decl (func_name) != NULL_TREE)
    return bytes_consumed;
  tree fndecl;
  tree ret_value = NULL_TREE;

  tree stmt_list = alloc_stmt_list ();

  /* Add a function scope BIND_EXPR using which we can push local variables that
     represent HSAIL registers.  */
  tree bind_expr = build3 (BIND_EXPR, void_type_node, NULL, stmt_list, NULL);

  tree restrict_char_ptr
    = build_qualified_type (build_pointer_type (char_type_node),
			    TYPE_QUAL_RESTRICT);
  tree restrict_void_ptr
    = build_qualified_type (build_pointer_type (void_type_node),
			    TYPE_QUAL_RESTRICT);

  tree restrict_const_char_ptr
    = build_qualified_type (build_pointer_type
			    (build_qualified_type (char_type_node,
						   TYPE_QUAL_CONST)),
			    TYPE_QUAL_RESTRICT);

  tree restrict_const_void_ptr
    = build_qualified_type (build_pointer_type
			    (build_qualified_type (void_type_node,
						   TYPE_QUAL_CONST)),
			    TYPE_QUAL_RESTRICT);

  if (is_kernel)
    {
      tree name_identifier
	= get_identifier_with_length (func_name.c_str (), func_name.size ());

      /* The generated kernel functions take the following arguments:

	 1) a char* which is a starting address of the argument segment where
	 the call's arguments are stored by the launcher.
	 2) a void* parameter that points to a phsail-finalizer context object
	 which passes the hsa kernel packet etc.
	 3) a void* parameter that contains the first flat address of the group
	 region allocated to the current work-group.  */

      fndecl = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL, name_identifier,
			   build_function_type_list (void_type_node,
						     restrict_const_char_ptr,
						     restrict_void_ptr,
						     restrict_char_ptr, NULL_TREE));

      SET_DECL_ASSEMBLER_NAME (fndecl, name_identifier);

      tree resdecl
	= build_decl (UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE, void_type_node);

      tree typelist = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
      tree argtype = TREE_VALUE (typelist);
      TYPE_ADDR_SPACE (argtype)
	= gccbrig_get_target_addr_space_id (BRIG_SEGMENT_KERNARG);

      tree arg_arg = build_decl (UNKNOWN_LOCATION, PARM_DECL,
				 get_identifier ("__args"),
				 restrict_const_char_ptr);
      DECL_ARGUMENTS (fndecl) = arg_arg;
      DECL_ARG_TYPE (arg_arg) = restrict_const_char_ptr;
      DECL_CONTEXT (arg_arg) = fndecl;
      DECL_ARTIFICIAL (arg_arg) = 1;
      TREE_READONLY (arg_arg) = 1;
      TREE_USED (arg_arg) = 1;

      DECL_RESULT (fndecl) = resdecl;
      DECL_CONTEXT (resdecl) = fndecl;
      DECL_EXTERNAL (fndecl) = 0;

      /* Aggressive inlining to the kernel function is usually a good
	 idea with offlined functionality to enchance SIMD execution on
	 GPUs and vector units.  */

      DECL_ATTRIBUTES (fndecl)
	= tree_cons (get_identifier ("flatten"), NULL,
		     DECL_ATTRIBUTES (fndecl));
    }
  else
    {
      /* Build a regular function fingerprint to enable targets to optimize
	 the calling convention as they see fit.  */
      tree name_identifier
	= get_identifier_with_length (func_name.c_str (), func_name.size ());

      m_parent.m_cf->m_arg_variables.clear ();

      brig_directive_variable_handler arg_handler (m_parent);

      vec<tree, va_gc> *args;
      vec_alloc (args, 4);

      tree arg_decls = NULL_TREE;

      tree ret_type = void_type_node;
      if (exec->outArgCount == 1)
	{
	  /* The return value variable should be the first entry after the
	     function directive.  */
	  const BrigBase *retval
	    = (const BrigBase *) ((const char *) base + base->byteCount);
	  gcc_assert (retval->kind == BRIG_KIND_DIRECTIVE_VARIABLE);

	  const BrigDirectiveVariable *brigVar
	    = (const BrigDirectiveVariable *) retval;

	  brig_directive_variable_handler varhandler (m_parent);

	  if (brigVar->type & BRIG_TYPE_ARRAY)
	    {
	      /* Push array output arguments to the beginning of the
		 function argument list instead of regular function
		 return values.  */

	      tree arg_var = varhandler.build_variable (brigVar, PARM_DECL);
	      vec_safe_push (args, TREE_TYPE (arg_var));

	      m_parent.m_cf->add_arg_variable (brigVar, arg_var);

	      if (arg_decls == NULL_TREE)
		arg_decls = arg_var;
	      else
		arg_decls = chainon (arg_decls, arg_var);

	      m_parent.m_cf->add_arg_variable (brigVar, arg_var);

	      ret_value = build_decl (UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE,
				      void_type_node);
	    }
	  else
	    {
	      ret_value = varhandler.build_variable (brigVar, RESULT_DECL);
	      m_parent.m_cf->m_ret_value = ret_value;
	      ret_type = TREE_TYPE (ret_value);
	      m_parent.m_cf->m_ret_value_brig_var = brigVar;
	    }
	  bytes_consumed += retval->byteCount;
	}
      else
	ret_value = build_decl (UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE,
				void_type_node);

      TREE_ADDRESSABLE (ret_value) = 1;

      if (exec->inArgCount > 0)
	{
	  uint32_t arg_offset = exec->firstInArg;
	  for (size_t arg = 0; arg < exec->inArgCount; ++arg)
	    {

	      const BrigDirectiveVariable *brigVar
		= (const BrigDirectiveVariable *) m_parent.get_brig_code_entry
		(arg_offset);

	      gcc_assert (brigVar->base.kind == BRIG_KIND_DIRECTIVE_VARIABLE);

	      /* Delegate to the brig_directive_variable_handler.  */
	      brig_directive_variable_handler varhandler (m_parent);
	      tree arg_var = varhandler.build_variable (brigVar, PARM_DECL);
	      arg_offset += brigVar->base.byteCount;
	      vec_safe_push (args, TREE_TYPE (arg_var));

	      m_parent.m_cf->add_arg_variable (brigVar, arg_var);
	      arg_decls = chainon (arg_decls, arg_var);
	    }
	}
      vec_safe_push (args, restrict_void_ptr);
      vec_safe_push (args, restrict_char_ptr);
      vec_safe_push (args, uint32_type_node);
      vec_safe_push (args, restrict_char_ptr);

      fndecl = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL, name_identifier,
			   build_function_type_vec (ret_type, args));

      DECL_RESULT (fndecl) = ret_value;
      DECL_CONTEXT (ret_value) = fndecl;
      DECL_EXTERNAL (fndecl) = 0;
      DECL_ARGUMENTS (fndecl) = arg_decls;
    }

  /* All functions need the hidden __context argument passed on
     because they might call WI-specific functions which need
     the context info.  Only kernels can write it, if they need
     to update the local ids in the work-item loop.  */

  tree context_arg_type
    = true ? restrict_void_ptr : restrict_const_void_ptr;
  tree context_arg = build_decl (UNKNOWN_LOCATION, PARM_DECL,
				 get_identifier ("__context"),
				 context_arg_type);
  DECL_ARGUMENTS (fndecl) = chainon (DECL_ARGUMENTS (fndecl), context_arg);
  DECL_CONTEXT (context_arg) = fndecl;
  DECL_ARG_TYPE (context_arg) = context_arg_type;
  DECL_ARTIFICIAL (context_arg) = 1;
  TREE_READONLY (context_arg) = 1;
  TREE_USED (context_arg) = 1;
  m_parent.m_cf->m_context_arg = context_arg;

  /* They can also access group memory, so we need to pass the
     group pointer along too.  */
  tree group_base_arg
    = build_decl (UNKNOWN_LOCATION, PARM_DECL,
		  get_identifier ("__group_base_addr"),
		  restrict_char_ptr);
  DECL_ARGUMENTS (fndecl) = chainon (DECL_ARGUMENTS (fndecl), group_base_arg);
  DECL_ARG_TYPE (group_base_arg) = restrict_char_ptr;
  DECL_CONTEXT (group_base_arg) = fndecl;
  DECL_ARTIFICIAL (group_base_arg) = 1;
  TREE_READONLY (group_base_arg) = 1;
  TREE_USED (group_base_arg) = 1;
  m_parent.m_cf->m_group_base_arg = group_base_arg;

  /* To implement call stack and (non-kernel) function scope group variables,
     we need to pass an offset which describes how far are we from
     group_base_ptr.
     That must be substracted from any function local group variable offsets to
     get the address related to the bottom of the group memory chunk.  */
  tree group_local_offset_arg
    = build_decl (UNKNOWN_LOCATION, PARM_DECL,
		  get_identifier ("__group_local_offset"), uint32_type_node);
  DECL_ARGUMENTS (fndecl) = chainon (DECL_ARGUMENTS (fndecl), group_local_offset_arg);
  DECL_ARG_TYPE (group_local_offset_arg) = uint32_type_node;
  DECL_CONTEXT (group_local_offset_arg) = fndecl;
  DECL_ARTIFICIAL (group_local_offset_arg) = 1;
  TREE_READONLY (group_local_offset_arg) = 1;
  TREE_USED (group_local_offset_arg) = 1;
  m_parent.m_cf->m_group_local_offset_arg = group_local_offset_arg;

  /* Same for private.  */
  tree private_base_arg
    = build_decl (UNKNOWN_LOCATION, PARM_DECL,
		  get_identifier ("__private_base_addr"), restrict_char_ptr);
  DECL_ARGUMENTS (fndecl) = chainon (DECL_ARGUMENTS (fndecl), private_base_arg);
  DECL_ARG_TYPE (private_base_arg) = restrict_char_ptr;
  DECL_CONTEXT (private_base_arg) = fndecl;
  DECL_ARTIFICIAL (private_base_arg) = 1;
  TREE_READONLY (private_base_arg) = 1;
  TREE_USED (private_base_arg) = 1;
  m_parent.m_cf->m_private_base_arg = private_base_arg;

  DECL_SAVED_TREE (fndecl) = bind_expr;

  if (base->kind == BRIG_KIND_DIRECTIVE_FUNCTION)
    {
      TREE_STATIC (fndecl) = 0;
      TREE_PUBLIC (fndecl) = 1;
      DECL_EXTERNAL (fndecl) = 0;
      DECL_DECLARED_INLINE_P (fndecl) = 1;
      set_inline (fndecl);
      set_externally_visible (fndecl);
    }
  else if (base->kind == BRIG_KIND_DIRECTIVE_KERNEL)
    {
      TREE_STATIC (fndecl) = 0;
      TREE_PUBLIC (fndecl) = 1;
      DECL_EXTERNAL (fndecl) = 0;
      set_externally_visible (fndecl);
    }
  else if (base->kind == BRIG_KIND_DIRECTIVE_SIGNATURE)
    {
      TREE_STATIC (fndecl) = 0;
      TREE_PUBLIC (fndecl) = 1;
      DECL_EXTERNAL (fndecl) = 1;
      set_inline (fndecl);
    }
  else if (base->kind == BRIG_KIND_DIRECTIVE_INDIRECT_FUNCTION)
    {
      TREE_STATIC (fndecl) = 0;
      TREE_PUBLIC (fndecl) = 1;
    }
  else
    gcc_unreachable ();

  TREE_USED (fndecl) = 1;
  DECL_ARTIFICIAL (fndecl) = 0;

  tree initial_block = make_node (BLOCK);
  DECL_INITIAL (fndecl) = initial_block;
  TREE_USED (DECL_INITIAL (fndecl)) = 1;

  if (ret_value != NULL_TREE && TREE_TYPE (ret_value) != void_type_node)
    {
      DECL_CONTEXT (ret_value) = fndecl;
      DECL_CHAIN (ret_value) = BIND_EXPR_VARS (bind_expr);
      BIND_EXPR_VARS (bind_expr) = ret_value;
    }

  tree arg;
  for (arg = DECL_ARGUMENTS (fndecl); arg != NULL_TREE; arg = TREE_CHAIN (arg))
    {
      DECL_CONTEXT (arg) = fndecl;
      DECL_ARG_TYPE (arg) = TREE_TYPE (arg);
    }

  m_parent.add_function_decl (func_name, fndecl);
  m_parent.append_global (fndecl);


  if (!is_definition)
    {
      DECL_EXTERNAL (fndecl) = 1;
      return bytes_consumed;
    }

  m_parent.start_function (fndecl);
  m_parent.m_cf->m_func_decl = fndecl;
  m_parent.m_cf->m_current_bind_expr = bind_expr;

  if (ret_value != NULL_TREE && TREE_TYPE (ret_value) != void_type_node)
    {
      /* We cannot assign to <<retval>> directly in gcc trunk.  We need to
	 create a local temporary variable which can be stored to and when
	 returning from the function, we'll copy it to the actual <<retval>>
	 in return statement's argument.  */
      tree temp_var = m_parent.m_cf->m_ret_temp
	= m_parent.m_cf->add_local_variable ("_retvalue_temp",
					     TREE_TYPE (ret_value));
      TREE_ADDRESSABLE (temp_var) = 1;
    }

  if (is_kernel)
    {
      m_parent.m_cf->add_id_variables ();

      /* Create a single entry point in the function.  */
      m_parent.m_cf->m_entry_label_stmt
	= build_stmt (LABEL_EXPR, m_parent.m_cf->label ("__kernel_entry"));
      m_parent.m_cf->append_statement (m_parent.m_cf->m_entry_label_stmt);

      tree bind_expr = m_parent.m_cf->m_current_bind_expr;
      tree stmts = BIND_EXPR_BODY (bind_expr);

      m_parent.m_cf->m_kernel_entry = tsi_last (stmts);

      /* Let's not append the exit label yet, but only after the
	 function has been built.  We need to build it so it can
	 be referred to because returns are converted to gotos to this
	 label.  */
      m_parent.m_cf->m_exit_label = m_parent.m_cf->label ("__kernel_exit");
    }

  return bytes_consumed;
}