[PATCH] Make SCCVN use an obstack for aux data sturctures

[Richard Guenther <rguenther at suse dot de>]

This patch by Steven implements $SUBJECT which should save some time
and memory.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to mainline.

Richard.

2008-02-28  Steven Bosscher  <stevenb.gcc@gmail.com>

	* tree-ssa-sccvn (vn_ssa_aux_obstack): New obstack.
	(VN_INFO_GET): Allocate new objects on the obstack.
	(init_scc_vn): Initialize the obstack.  Use XDELETE instead of free
	for rpo_numbers_temp, for consistency.
	(free_scc_vn): Free the obstack.

Index: tree-ssa-sccvn.c
===================================================================
*** tree-ssa-sccvn.c	(revision 131489)
--- tree-ssa-sccvn.c	(working copy)
*************** static VEC (tree, heap) *sccstack;
*** 241,249 ****
  DEF_VEC_P(vn_ssa_aux_t);
  DEF_VEC_ALLOC_P(vn_ssa_aux_t, heap);
  
! /* Table of vn_ssa_aux_t's, one per ssa_name.  */
  
  static VEC (vn_ssa_aux_t, heap) *vn_ssa_aux_table;
  
  /* Return the value numbering information for a given SSA name.  */
  
--- 241,252 ----
  DEF_VEC_P(vn_ssa_aux_t);
  DEF_VEC_ALLOC_P(vn_ssa_aux_t, heap);
  
! /* Table of vn_ssa_aux_t's, one per ssa_name.  The vn_ssa_aux_t objects
!    are allocated on an obstack for locality reasons, and to free them
!    without looping over the VEC.  */
  
  static VEC (vn_ssa_aux_t, heap) *vn_ssa_aux_table;
+ static struct obstack vn_ssa_aux_obstack;
  
  /* Return the value numbering information for a given SSA name.  */
  
*************** VN_INFO_SET (tree name, vn_ssa_aux_t val
*** 264,276 ****
  	       SSA_NAME_VERSION (name), value);
  }
  
! /* Get the value numbering info for a given SSA name, creating it if
!    it does not exist.  */
  
  vn_ssa_aux_t
  VN_INFO_GET (tree name)
  {
!   vn_ssa_aux_t newinfo = XCNEW (struct vn_ssa_aux);
    if (SSA_NAME_VERSION (name) >= VEC_length (vn_ssa_aux_t, vn_ssa_aux_table))
      VEC_safe_grow (vn_ssa_aux_t, heap, vn_ssa_aux_table,
  		   SSA_NAME_VERSION (name) + 1);
--- 267,282 ----
  	       SSA_NAME_VERSION (name), value);
  }
  
! /* Initialize the value numbering info for a given SSA name.
!    This should be called just once for every SSA name.  */
  
  vn_ssa_aux_t
  VN_INFO_GET (tree name)
  {
!   vn_ssa_aux_t newinfo;
! 
!   newinfo = obstack_alloc (&vn_ssa_aux_obstack, sizeof (struct vn_ssa_aux));
!   memset (newinfo, 0, sizeof (struct vn_ssa_aux));
    if (SSA_NAME_VERSION (name) >= VEC_length (vn_ssa_aux_t, vn_ssa_aux_table))
      VEC_safe_grow (vn_ssa_aux_t, heap, vn_ssa_aux_table,
  		   SSA_NAME_VERSION (name) + 1);
*************** init_scc_vn (void)
*** 2005,2010 ****
--- 2011,2018 ----
    /* VEC_alloc doesn't actually grow it to the right size, it just
       preallocates the space to do so.  */
    VEC_safe_grow (vn_ssa_aux_t, heap, vn_ssa_aux_table, num_ssa_names + 1);
+   gcc_obstack_init (&vn_ssa_aux_obstack);
+ 
    shared_lookup_phiargs = NULL;
    shared_lookup_vops = NULL;
    shared_lookup_references = NULL;
*************** init_scc_vn (void)
*** 2018,2024 ****
    for (j = 0; j < n_basic_blocks - NUM_FIXED_BLOCKS; j++)
      rpo_numbers[rpo_numbers_temp[j]] = j;
  
!   free (rpo_numbers_temp);
  
    VN_TOP = create_tmp_var_raw (void_type_node, "vn_top");
  
--- 2026,2032 ----
    for (j = 0; j < n_basic_blocks - NUM_FIXED_BLOCKS; j++)
      rpo_numbers[rpo_numbers_temp[j]] = j;
  
!   XDELETE (rpo_numbers_temp);
  
    VN_TOP = create_tmp_var_raw (void_type_node, "vn_top");
  
*************** free_scc_vn (void)
*** 2069,2087 ****
    VEC_free (tree, gc, shared_lookup_vops);
    VEC_free (vn_reference_op_s, heap, shared_lookup_references);
    XDELETEVEC (rpo_numbers);
    for (i = 0; i < num_ssa_names; i++)
      {
        tree name = ssa_name (i);
!       if (name)
! 	{
! 	  XDELETE (VN_INFO (name));
! 	  if (SSA_NAME_VALUE (name) &&
! 	      TREE_CODE (SSA_NAME_VALUE (name)) == VALUE_HANDLE)
! 	    SSA_NAME_VALUE (name) = NULL;
! 	}
      }
! 
    VEC_free (vn_ssa_aux_t, heap, vn_ssa_aux_table);
    VEC_free (tree, heap, sccstack);
    free_vn_table (valid_info);
    XDELETE (valid_info);
--- 2077,2094 ----
    VEC_free (tree, gc, shared_lookup_vops);
    VEC_free (vn_reference_op_s, heap, shared_lookup_references);
    XDELETEVEC (rpo_numbers);
+ 
    for (i = 0; i < num_ssa_names; i++)
      {
        tree name = ssa_name (i);
!       if (name
! 	  && SSA_NAME_VALUE (name)
! 	  && TREE_CODE (SSA_NAME_VALUE (name)) == VALUE_HANDLE)
! 	SSA_NAME_VALUE (name) = NULL;
      }
!   obstack_free (&vn_ssa_aux_obstack, NULL);
    VEC_free (vn_ssa_aux_t, heap, vn_ssa_aux_table);
+ 
    VEC_free (tree, heap, sccstack);
    free_vn_table (valid_info);
    XDELETE (valid_info);