http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45830
Summary: [4.4/4.5/4.6 Regression] Code+rodata increase with
-ftree-switch-conversion
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ja...@gcc.gnu.org
CC: jamb...@gcc.gnu.org
int
foo (int *a)
{
switch (*a)
{
case 0:
case 3:
case 1:
case 2:
case 4:
case 23:
case 26:
case 19:
case 5:
case 21:
case 20:
case 22:
case 27:
return 1;
default:
return 0;
}
}
generates significantly shorter code+rodata with -fno-tree-switch-conversion
than without. I guess for the cases where
if (CASE_USE_BIT_TESTS
&& ! TREE_CONSTANT (index_expr)
&& compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
&& compare_tree_int (range, 0) > 0
&& lshift_cheap_p ()
&& ((uniq == 1 && count >= 3)
|| (uniq == 2 && count >= 5)
|| (uniq == 3 && count >= 6)))
is true tree-switch-conversion.c should not perform the optimization, and
in any case the question is if the table needs to be created always for the
type of the constants, even when they are integral and would fit into narrower
integer type (like char/unsigned char in this case).
