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gimple-fold.c (gimple_get_virt_method_for_vtable): Do O(1) lookup in the vtable constructor. 

* gimple-fold.c (gimple_get_virt_method_for_vtable): Do O(1)
	lookup in the vtable constructor.

From-SVN: r207616
This commit is contained in:
Jan Hubicka 2014-02-08 00:26:39 +01:00 committed by Jan Hubicka
parent 63e6247dfe
commit 8c311b50d1
2 changed files with 32 additions and 4 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2014-02-07 Jan Hubicka <hubicka@ucw.cz>
* gimple-fold.c (gimple_get_virt_method_for_vtable): Do O(1)
lookup in the vtable constructor.
2014-02-07 Jeff Law <law@redhat.com>
PR target/40977

31
gcc/gimple-fold.c
View File

@ -3179,6 +3179,8 @@ gimple_get_virt_method_for_vtable (HOST_WIDE_INT token,
{
tree vtable = v, init, fn;
unsigned HOST_WIDE_INT size;
unsigned HOST_WIDE_INT elt_size, access_index;
tree domain_type;
/* First of all double check we have virtual table. */
if (TREE_CODE (v) != VAR_DECL
@ -3202,10 +3204,31 @@ gimple_get_virt_method_for_vtable (HOST_WIDE_INT token,
offset *= BITS_PER_UNIT;
offset += token * size;
/* Do not pass from_decl here, we want to know even about values we can
not use and will check can_refer_decl_in_current_unit_p ourselves. */
fn = fold_ctor_reference (TREE_TYPE (TREE_TYPE (v)), init,
offset, size, NULL);
/* Lookup the value in the constructor that is assumed to be array.
This is equivalent to
fn = fold_ctor_reference (TREE_TYPE (TREE_TYPE (v)), init,
offset, size, NULL);
but in a constant time. We expect that frontend produced a simple
array without indexed initializers. */
gcc_checking_assert (TREE_CODE (TREE_TYPE (init)) == ARRAY_TYPE);
domain_type = TYPE_DOMAIN (TREE_TYPE (init));
gcc_checking_assert (integer_zerop (TYPE_MIN_VALUE (domain_type)));
elt_size = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (init))));
access_index = offset / BITS_PER_UNIT / elt_size;
gcc_checking_assert (offset % (elt_size * BITS_PER_UNIT) == 0);
/* This code makes an assumption that there are no
indexed fileds produced by C++ FE, so we can directly index the array. */
if (access_index < CONSTRUCTOR_NELTS (init))
{
fn = CONSTRUCTOR_ELT (init, access_index)->value;
gcc_checking_assert (!CONSTRUCTOR_ELT (init, access_index)->index);
STRIP_NOPS (fn);
}
else
fn = NULL;
/* For type inconsistent program we may end up looking up virtual method
in virtual table that does not contain TOKEN entries. We may overrun