Re: (Re)allocation of allocatable arrays on assignment - F2003

[Paul Richard Thomas <paul dot richard dot thomas at gmail dot com>]

Lordy, am I suffering from fingers problems today!  Ignore the last
version of the patch.  That was from first thing this morning.

By the way, you will see from the code that if the lhs and rhs sizes
are the same, control jumps past the new block.  I cannot see any
measurable performance loss.

Paul

Index: gcc/fortran/trans-array.c
===================================================================
*** gcc/fortran/trans-array.c	(revision 164755)
--- gcc/fortran/trans-array.c	(working copy)
*************** gfc_trans_array_constructor (gfc_loopinf
*** 1830,1835 ****
--- 1830,1836 ----
    tree offsetvar;
    tree desc;
    tree type;
+   tree tmp;
    bool dynamic;
    bool old_first_len, old_typespec_chararray_ctor;
    tree old_first_len_val;
*************** gfc_trans_array_constructor (gfc_loopinf
*** 1942,1947 ****
--- 1943,1951 ----
  	}
      }
  
+   if (TREE_CODE (loop->to[0]) == VAR_DECL)
+     dynamic = true;
+ 
    gfc_trans_create_temp_array (&loop->pre, &loop->post, loop, &ss->data.info,
  			       type, NULL_TREE, dynamic, true, false, where);
  
*************** gfc_trans_array_constructor (gfc_loopinf
*** 1956,1967 ****
    /* If the array grows dynamically, the upper bound of the loop variable
       is determined by the array's final upper bound.  */
    if (dynamic)
!     loop->to[0] = gfc_conv_descriptor_ubound_get (desc, gfc_rank_cst[0]);
  
    if (TREE_USED (offsetvar))
      pushdecl (offsetvar);
    else
      gcc_assert (INTEGER_CST_P (offset));
  #if 0
    /* Disable bound checking for now because it's probably broken.  */
    if (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
--- 1960,1982 ----
    /* If the array grows dynamically, the upper bound of the loop variable
       is determined by the array's final upper bound.  */
    if (dynamic)
!     {
!       tmp = fold_build2_loc (input_location, MINUS_EXPR,
! 			     gfc_array_index_type,
! 			     offsetvar, gfc_index_one_node);
!       tmp = gfc_evaluate_now (tmp, &loop->pre);
!       gfc_conv_descriptor_ubound_set (&loop->pre, desc, gfc_rank_cst[0], tmp);
!       if (loop->to[0] && TREE_CODE (loop->to[0]) == VAR_DECL)
! 	gfc_add_modify (&loop->pre, loop->to[0], tmp);
!       else
! 	loop->to[0] = tmp;
!     }
  
    if (TREE_USED (offsetvar))
      pushdecl (offsetvar);
    else
      gcc_assert (INTEGER_CST_P (offset));
+ 
  #if 0
    /* Disable bound checking for now because it's probably broken.  */
    if (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
*************** gfc_conv_ss_descriptor (stmtblock_t * bl
*** 2174,2179 ****
--- 2189,2199 ----
  
        tmp = gfc_conv_array_offset (se.expr);
        ss->data.info.offset = gfc_evaluate_now (tmp, block);
+ 
+       /* Make absolutely sure that the saved_offset is indeed saved
+ 	 so that the variable is still accessible after the loops
+ 	 are translated.  */
+       ss->data.info.saved_offset = ss->data.info.offset;
      }
  }
  
*************** gfc_copy_only_alloc_comp (gfc_symbol * d
*** 6449,6454 ****
--- 6469,6757 ----
  }
  
  
+ /* Returns the value of LBOUND for an expression.  This could be broken out
+    from gfc_conv_intrinsic_bound but this seemed to be simpler.  This is
+    called by gfc_alloc_allocatable_for_assignment.  */
+ static tree
+ get_std_lbound (gfc_expr *expr, tree desc, int dim, bool assumed_size)
+ {
+   tree lbound;
+   tree ubound;
+   tree stride;
+   tree cond, cond1, cond3, cond4;
+   tree tmp;
+   if (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (desc)))
+     {
+       tmp = gfc_rank_cst[dim];
+       lbound = gfc_conv_descriptor_lbound_get (desc, tmp);
+       ubound = gfc_conv_descriptor_ubound_get (desc, tmp);
+       stride = gfc_conv_descriptor_stride_get (desc, tmp);
+       cond1 = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
+ 			       ubound, lbound);
+       cond3 = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
+ 			       stride, gfc_index_zero_node);
+       cond3 = fold_build2_loc (input_location, TRUTH_AND_EXPR,
+ 			       boolean_type_node, cond3, cond1);
+       cond4 = fold_build2_loc (input_location, LT_EXPR, boolean_type_node,
+ 			       stride, gfc_index_zero_node);
+       if (assumed_size)
+ 	cond = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
+ 				tmp, build_int_cst (gfc_array_index_type,
+ 						    expr->rank - 1));
+       else
+ 	cond = boolean_false_node;
+ 
+       cond1 = fold_build2_loc (input_location, TRUTH_OR_EXPR,
+ 			       boolean_type_node, cond3, cond4);
+       cond = fold_build2_loc (input_location, TRUTH_OR_EXPR,
+ 			      boolean_type_node, cond, cond1);
+ 
+       return fold_build3_loc (input_location, COND_EXPR,
+ 			      gfc_array_index_type, cond,
+ 			      lbound, gfc_index_one_node);
+     }
+   else if (expr->expr_type == EXPR_VARIABLE)
+     {
+       tmp = TREE_TYPE (expr->symtree->n.sym->backend_decl);
+       return GFC_TYPE_ARRAY_LBOUND(tmp, dim);
+     }
+ 
+   return gfc_index_one_node;
+ }
+ 
+ /* Allocate the lhs of an assignment to an allocatable array, otherwise
+    reallocate it.  */
+ 
+ void
+ gfc_alloc_allocatable_for_assignment (gfc_loopinfo *loop,
+ 				      gfc_expr *expr1,
+ 				      gfc_expr *expr2)
+ {
+   stmtblock_t realloc_block;
+   stmtblock_t alloc_block;
+   stmtblock_t fblock;
+   gfc_ss *rss;
+   gfc_ss *lss;
+   tree realloc_expr;
+   tree alloc_expr;
+   tree size1;
+   tree size2;
+   tree array1;
+   tree cond;
+   tree tmp;
+   tree tmp2;
+   tree lbound;
+   tree ubound;
+   tree desc;
+   tree desc2;
+   tree offset;
+   tree jump_label;
+   tree lbd;
+   int n, dim;
+   gfc_array_spec * as;
+ 
+   if (!expr1->symtree->n.sym->attr.allocatable
+ 	|| (expr1->ref && expr1->ref->type == REF_ARRAY
+ 	      && expr1->ref->u.ar.type != AR_FULL)
+ 	|| !expr2->rank)
+     return;
+ 
+   /* Find the ss for the lhs.  */
+   lss = loop->ss;
+   for (; lss && lss != gfc_ss_terminator; lss = lss->loop_chain)
+     if (lss->expr == expr1)
+       break;
+ 
+   if (lss == gfc_ss_terminator)
+     return;
+ 
+   /* Find the ss for the rhs.  */
+   rss = loop->ss;
+   for (; rss && rss != gfc_ss_terminator; rss = rss->loop_chain)
+     if (rss->expr == expr2)
+       break;
+ 
+   if (rss == gfc_ss_terminator)
+     return;
+ 
+   gfc_start_block (&fblock);
+ 
+   /* Since the lhs data and array size.  */
+   desc = lss->data.info.descriptor;
+   gcc_assert (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (desc)));
+   array1 = gfc_conv_descriptor_data_get (desc);
+   size1 = gfc_conv_descriptor_size (desc, expr1->rank);
+ 
+   /* Get the rhs size.  Fix both sizes.  */
+   desc2 = rss->data.info.descriptor;
+   size2 = gfc_index_one_node;
+   for (n = 0; n < expr2->rank; n++)
+     {
+       dim = rss->data.info.dim[n];
+       tmp = fold_build2_loc (input_location, MINUS_EXPR,
+ 			     gfc_array_index_type,
+ 			     loop->to[dim], loop->from[dim]);
+       tmp = fold_build2_loc (input_location, PLUS_EXPR,
+ 			     gfc_array_index_type,
+ 			     tmp, gfc_index_one_node);
+       size2 = fold_build2_loc (input_location, MULT_EXPR,
+ 			       gfc_array_index_type,
+ 			       tmp, size2);
+     }
+   size1 = gfc_evaluate_now (size1, &fblock);
+   size2 = gfc_evaluate_now (size2, &fblock);
+ 
+   /* If the lhs is allocated and the lhs and rhs are equal length, jump
+      past the realloc/malloc.  This allows F95 compliant expressions
+      to escape allocation on assignment.  */
+   jump_label = gfc_build_label_decl (NULL_TREE);
+   tmp = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
+ 			 array1, build_int_cst (TREE_TYPE (array1), 0));
+   tmp2 = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
+ 			  size1, size2);
+   cond = fold_build2_loc (input_location, TRUTH_AND_EXPR,
+ 			  boolean_type_node, tmp, tmp2);
+   tmp = build3_v (COND_EXPR, cond,
+ 		  build1_v (GOTO_EXPR, jump_label),
+ 		  build_empty_stmt (input_location));
+ 
+   gfc_add_expr_to_block (&fblock, tmp);
+ 
+   /* Now modify the lhs descriptor and the associated scalarizer
+      variables.
+      7.4.1.3: If variable is or becomes an unallocated allocatable
+      variable, then it is allocated with each deferred type parameter
+      equal to the corresponding type parameters of expr , with the
+      shape of expr , and with each lower bound equal to the
+      corresponding element of LBOUND(expr ).  */
+   size1 = gfc_index_one_node;
+   offset = gfc_index_zero_node;
+   as = gfc_get_full_arrayspec_from_expr (expr2);
+   for (n = 0; n < expr2->rank; n++)
+     {
+       dim = rss->data.info.dim[n];
+       tmp = fold_build2_loc (input_location, MINUS_EXPR,
+ 			     gfc_array_index_type,
+ 			     loop->to[dim], loop->from[dim]);
+       tmp = fold_build2_loc (input_location, PLUS_EXPR,
+ 			     gfc_array_index_type,
+ 			     tmp, gfc_index_one_node);
+       lbound = loop->from[dim];
+       ubound = loop->to[dim];
+       if (as && !lss->data.info.ref)
+ 	{
+ 	  lbd = get_std_lbound (expr2, desc2, n,
+ 				as->type == AS_ASSUMED_SIZE);
+ 	  ubound = fold_build2_loc (input_location,
+ 				    MINUS_EXPR,
+ 				    gfc_array_index_type,
+ 				    ubound, lbound);
+ 	  ubound = fold_build2_loc (input_location,
+ 				    PLUS_EXPR,
+ 				    gfc_array_index_type,
+ 				    ubound, lbd);
+ 	  lbound = lbd;
+ 	}
+ 
+       gfc_conv_descriptor_lbound_set (&fblock, desc,
+ 				      gfc_rank_cst[n],
+ 				      lbound);
+       gfc_conv_descriptor_ubound_set (&fblock, desc,
+ 				      gfc_rank_cst[n],
+ 				      ubound);
+       gfc_conv_descriptor_stride_set (&fblock, desc,
+ 				      gfc_rank_cst[n],
+ 				      size1);
+       lbound = gfc_conv_descriptor_lbound_get (desc,
+ 					       gfc_rank_cst[n]);
+       tmp2 = fold_build2_loc (input_location, MULT_EXPR,
+ 			      gfc_array_index_type,
+ 			      lbound, size1);
+       offset = fold_build2_loc (input_location, MINUS_EXPR,
+ 				gfc_array_index_type,
+ 				offset, tmp2);
+       size1 = fold_build2_loc (input_location, MULT_EXPR,
+ 			       gfc_array_index_type,
+ 			       tmp, size1);
+     }
+ 
+   /* Set the lhs descriptor and scalarizer offsets.  For rank > 1,
+      the array offset is saved and the info.offset is used for a
+      running offset.  Use the saved_offset instead.  */
+   tmp = gfc_conv_descriptor_offset (desc);
+   gfc_add_modify (&fblock, tmp, offset);
+   if (lss->data.info.saved_offset
+ 	&& TREE_CODE (lss->data.info.saved_offset) == VAR_DECL)
+       gfc_add_modify (&fblock, lss->data.info.saved_offset, tmp);
+ 
+   /* Now set the deltas for the lhs.  */
+   for (n = 0; n < expr2->rank; n++)
+     {
+       tmp = gfc_conv_descriptor_lbound_get (desc, gfc_rank_cst[n]);
+       dim = lss->data.info.dim[n];
+       tmp = fold_build2_loc (input_location, MINUS_EXPR,
+ 			     gfc_array_index_type, tmp,
+ 			     loop->from[dim]);
+       if (lss->data.info.delta[dim]
+ 	    && TREE_CODE (lss->data.info.delta[dim]) == VAR_DECL)
+ 	gfc_add_modify (&fblock, lss->data.info.delta[dim], tmp);
+     }
+ 
+   /* Get the new lhs size in bytes.  */
+   tmp = TYPE_SIZE_UNIT (gfc_typenode_for_spec (&expr2->ts));
+   tmp = fold_convert (gfc_array_index_type, tmp);
+   size2 = fold_build2_loc (input_location, MULT_EXPR,
+ 			   gfc_array_index_type,
+ 			   tmp, size2);
+   size2 = fold_convert (size_type_node, size2);
+   size2 = gfc_evaluate_now (size2, &fblock);
+ 
+   /* Realloc expression.  Note that the scalarizer uses desc.data
+      in the array reference - (*desc.data)[<element>]. */
+   gfc_init_block (&realloc_block);
+   tmp = build_call_expr_loc (input_location,
+ 			     built_in_decls[BUILT_IN_REALLOC], 2,
+ 			     fold_convert (pvoid_type_node, array1),
+ 			     size2);
+   gfc_conv_descriptor_data_set (&realloc_block,
+ 				desc, tmp);
+   realloc_expr = gfc_finish_block (&realloc_block);
+ 
+   /* Malloc expression.  */
+   gfc_init_block (&alloc_block);
+   tmp = build_call_expr_loc (input_location,
+ 			     built_in_decls[BUILT_IN_MALLOC], 1,
+ 			     size2);
+   gfc_conv_descriptor_data_set (&alloc_block,
+ 				desc, tmp);
+   tmp = gfc_conv_descriptor_dtype (desc);
+   gfc_add_modify (&alloc_block, tmp, gfc_get_dtype (TREE_TYPE (desc)));
+   alloc_expr = gfc_finish_block (&alloc_block);
+ 
+   /* Malloc if not allocated; realloc otherwise.  */
+   tmp = build_int_cst (TREE_TYPE (array1), 0);
+   cond = fold_build2_loc (input_location, EQ_EXPR,
+ 			  boolean_type_node,
+ 			  array1, tmp);
+   tmp = build3_v (COND_EXPR, cond, alloc_expr, realloc_expr);
+   gfc_add_expr_to_block (&fblock, tmp);
+ 
+   if (lss->data.info.data
+ 	&& TREE_CODE (lss->data.info.data) == VAR_DECL)
+     {
+       tmp = gfc_conv_descriptor_data_get (desc);
+       gfc_add_modify (&fblock, lss->data.info.data, tmp);
+     }
+ 
+   /* Add the exit label.  */
+   tmp = build1_v (LABEL_EXPR, jump_label);
+   gfc_add_expr_to_block (&fblock, tmp);
+ 
+   tmp = gfc_finish_block (&fblock);
+   gfc_add_expr_to_block (&loop->pre, tmp);
+ }
+ 
+ 
  /* NULLIFY an allocatable/pointer array on function entry, free it on exit.
     Do likewise, recursively if necessary, with the allocatable components of
     derived types.  */
Index: gcc/fortran/trans-expr.c
===================================================================
*** gcc/fortran/trans-expr.c	(revision 164755)
--- gcc/fortran/trans-expr.c	(working copy)
*************** gfc_trans_assignment_1 (gfc_expr * expr1
*** 5744,5749 ****
--- 5744,5752 ----
  	  gfc_add_expr_to_block (&body, tmp);
  	}
  
+       /* Allocate or reallocate lhs of allocatable array.  */
+       gfc_alloc_allocatable_for_assignment (&loop, expr1, expr2);
+ 
        /* Generate the copying loops.  */
        gfc_trans_scalarizing_loops (&loop, &body);
  
Index: gcc/fortran/trans-array.h
===================================================================
*** gcc/fortran/trans-array.h	(revision 164755)
--- gcc/fortran/trans-array.h	(working copy)
*************** tree gfc_copy_alloc_comp (gfc_symbol *, 
*** 57,62 ****
--- 57,64 ----
  
  tree gfc_copy_only_alloc_comp (gfc_symbol *, tree, tree, int);
  
+ void gfc_alloc_allocatable_for_assignment (gfc_loopinfo*, gfc_expr*, gfc_expr*);
+ 
  /* Add initialization for deferred arrays.  */
  void gfc_trans_deferred_array (gfc_symbol *, gfc_wrapped_block *);
  /* Generate an initializer for a static pointer or allocatable array.  */