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re PR c++/42556 (Unnecessary generation of a zero initializer for array with C++)

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cp/
	PR c++/42556
	* typeck2.c (split_nonconstant_init_1): Drop empty CONSTRUCTOR
	when all of its elements are non-constant and have been split out.

	testsuite/
	PR c++/42556
	* g++.dg/init/pr42556.C: New test.

From-SVN: r158047
This commit is contained in:
Jie Zhang 2010-04-07 10:14:45 +00:00 • committed by Jie Zhang
parent 366f945f9b
commit 6addabbbe8
4 changed files with 41 additions and 3 deletions
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6
gcc/cp/ChangeLog
View file

@ -1,3 +1,9 @@
2010-04-07 Jie Zhang <jie@codesourcery.com>
PR c++/42556
* typeck2.c (split_nonconstant_init_1): Drop empty CONSTRUCTOR
when all of its elements are non-constant and have been split out.
2010-04-06 Taras Glek <taras@mozilla.com>
Jason Merrill <jason@redhat.com>

23
gcc/cp/typeck2.c
View file

@ -549,13 +549,15 @@ cxx_incomplete_type_error (const_tree value, const_tree type)
expression to which INIT should be assigned. INIT is a CONSTRUCTOR. */
static void
split_nonconstant_init_1 (tree dest, tree init)
split_nonconstant_init_1 (tree dest, tree *initp)
{
unsigned HOST_WIDE_INT idx;
tree init = *initp;
tree field_index, value;
tree type = TREE_TYPE (dest);
tree inner_type = NULL;
bool array_type_p = false;
HOST_WIDE_INT num_type_elements, num_initialized_elements;
switch (TREE_CODE (type))
{
@ -567,6 +569,7 @@ split_nonconstant_init_1 (tree dest, tree init)
case RECORD_TYPE:
case UNION_TYPE:
case QUAL_UNION_TYPE:
num_initialized_elements = 0;
FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (init), idx,
field_index, value)
{
@ -589,12 +592,13 @@ split_nonconstant_init_1 (tree dest, tree init)
sub = build3 (COMPONENT_REF, inner_type, dest, field_index,
NULL_TREE);
split_nonconstant_init_1 (sub, value);
split_nonconstant_init_1 (sub, &value);
}
else if (!initializer_constant_valid_p (value, inner_type))
{
tree code;
tree sub;
HOST_WIDE_INT inner_elements;
/* FIXME: Ordered removal is O(1) so the whole function is
worst-case quadratic. This could be fixed using an aside
@ -617,9 +621,22 @@ split_nonconstant_init_1 (tree dest, tree init)
code = build2 (INIT_EXPR, inner_type, sub, value);
code = build_stmt (input_location, EXPR_STMT, code);
add_stmt (code);
inner_elements = count_type_elements (inner_type, true);
if (inner_elements < 0)
num_initialized_elements = -1;
else if (num_initialized_elements >= 0)
num_initialized_elements += inner_elements;
continue;
}
}
num_type_elements = count_type_elements (type, true);
/* If all elements of the initializer are non-constant and
have been split out, we don't need the empty CONSTRUCTOR. */
if (num_type_elements > 0
&& num_type_elements == num_initialized_elements)
*initp = NULL;
break;
case VECTOR_TYPE:
@ -655,7 +672,7 @@ split_nonconstant_init (tree dest, tree init)
if (TREE_CODE (init) == CONSTRUCTOR)
{
code = push_stmt_list ();
split_nonconstant_init_1 (dest, init);
split_nonconstant_init_1 (dest, &init);
code = pop_stmt_list (code);
DECL_INITIAL (dest) = init;
TREE_READONLY (dest) = 0;

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2010-04-07 Jie Zhang <jie@codesourcery.com>
PR c++/42556
* g++.dg/init/pr42556.C: New test.
2010-04-07 Dodji Seketeli <dodji@redhat.com>
PR debug/43628

10
gcc/testsuite/g++.dg/init/pr42556.C Normal file
View file

@ -0,0 +1,10 @@
// { dg-do compile }
// { dg-options "-fdump-tree-gimple" }
void foo (int a, int b, int c, int d)
{
int v[4] = {a, b, c, d};
}
// { dg-final { scan-tree-dump-not "v = {}" "gimple" } }
// { dg-final { cleanup-tree-dump "gimple" } }