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* tree-ssa-dse.c (struct address_walk_data, memory_ssa_name_same)
	(memory_address_same): New.
	(dse_optimize_stmt): Call memory_address_same.
gcc/testsuite/
	* gcc.c-torture/execute/20051110-1.c,
	gcc.c-torture/execute/20051110-2.c: New tests.

From-SVN: r106807
This commit is contained in:
Daniel Jacobowitz 2005-11-11 23:23:15 +00:00 committed by Daniel Jacobowitz
parent 44087d555c
commit 6c14b137a9
5 changed files with 151 additions and 2 deletions
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6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2005-11-11 Daniel Jacobowitz <dan@codesourcery.com>
* tree-ssa-dse.c (struct address_walk_data, memory_ssa_name_same)
(memory_address_same): New.
(dse_optimize_stmt): Call memory_address_same.
2005-11-12 Hans-Peter Nilsson <hp@axis.com>
PR middle-end/24750

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2005-11-11 Daniel Jacobowitz <dan@codesourcery.com>
* gcc.c-torture/execute/20051110-1.c,
gcc.c-torture/execute/20051110-2.c: New tests.
2005-11-12 Hans-Peter Nilsson <hp@axis.com>
PR middle-end/24750

31
gcc/testsuite/gcc.c-torture/execute/20051110-1.c Normal file
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@ -0,0 +1,31 @@
void add_unwind_adjustsp (long);
void abort (void);
unsigned char bytes[5];
void
add_unwind_adjustsp (long offset)
{
int n;
unsigned long o;
o = (long) ((offset - 0x204) >> 2);
n = 0;
while (o)
{
bytes[n] = o & 0x7f;
o >>= 7;
if (o)
bytes[n] |= 0x80;
n++;
}
}
int main(void)
{
add_unwind_adjustsp (4132);
if (bytes[0] != 0x88 || bytes[1] != 0x07)
abort ();
return 0;
}

39
gcc/testsuite/gcc.c-torture/execute/20051110-2.c Normal file
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@ -0,0 +1,39 @@
void add_unwind_adjustsp (long);
void abort (void);
unsigned char bytes[5];
int flag;
void
add_unwind_adjustsp (long offset)
{
int n;
unsigned long o;
o = (long) ((offset - 0x204) >> 2);
n = 0;
do
{
a:
bytes[n] = o & 0x7f;
o >>= 7;
if (o)
{
bytes[n] |= 0x80;
if (flag)
goto a;
}
n++;
}
while (o);
}
int main(void)
{
add_unwind_adjustsp (4132);
if (bytes[0] != 0x88 || bytes[1] != 0x07)
abort ();
return 0;
}

72
gcc/tree-ssa-dse.c
View File

@ -83,6 +83,13 @@ struct dse_block_local_data
bitmap stores;
};
/* Basic blocks of the potentially dead store and the following
store, for memory_address_same. */
struct address_walk_data
{
basic_block store1_bb, store2_bb;
};
static bool gate_dse (void);
static void tree_ssa_dse (void);
static void dse_initialize_block_local_data (struct dom_walk_data *,
@ -145,6 +152,64 @@ dse_initialize_block_local_data (struct dom_walk_data *walk_data,
}
}
/* Helper function for memory_address_same via walk_tree. Returns
non-NULL if it finds an SSA_NAME which is part of the address,
such that the definition of the SSA_NAME post-dominates the store
we want to delete but not the store that we believe makes it
redundant. This indicates that the address may change between
the two stores. */
static tree
memory_ssa_name_same (tree *expr_p, int *walk_subtrees ATTRIBUTE_UNUSED,
void *data)
{
struct address_walk_data *walk_data = data;
tree expr = *expr_p;
tree def_stmt;
basic_block def_bb;
if (TREE_CODE (expr) != SSA_NAME)
return NULL_TREE;
/* If we've found a default definition, then there's no problem. Both
stores will post-dominate it. And def_bb will be NULL. */
if (expr == default_def (SSA_NAME_VAR (expr)))
return NULL_TREE;
def_stmt = SSA_NAME_DEF_STMT (expr);
def_bb = bb_for_stmt (def_stmt);
/* DEF_STMT must dominate both stores. So if it is in the same
basic block as one, it does not post-dominate that store. */
if (walk_data->store1_bb != def_bb
&& dominated_by_p (CDI_POST_DOMINATORS, walk_data->store1_bb, def_bb))
{
if (walk_data->store2_bb == def_bb
|| !dominated_by_p (CDI_POST_DOMINATORS, walk_data->store2_bb,
def_bb))
/* Return non-NULL to stop the walk. */
return def_stmt;
}
return NULL_TREE;
}
/* Return TRUE if the destination memory address in STORE1 and STORE2
might be modified after STORE1, before control reaches STORE2. */
static bool
memory_address_same (tree store1, tree store2)
{
struct address_walk_data walk_data;
walk_data.store1_bb = bb_for_stmt (store1);
walk_data.store2_bb = bb_for_stmt (store2);
return (walk_tree (&TREE_OPERAND (store1, 0), memory_ssa_name_same,
&walk_data, NULL)
== NULL);
}
/* Attempt to eliminate dead stores in the statement referenced by BSI.
A dead store is a store into a memory location which will later be
@ -251,11 +316,14 @@ dse_optimize_stmt (struct dom_walk_data *walk_data,
}
/* If we have precisely one immediate use at this point, then we may
have found redundant store. */
have found redundant store. Make sure that the stores are to
the same memory location. This includes checking that any
SSA-form variables in the address will have the same values. */
if (use_p != NULL_USE_OPERAND_P
&& bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
&& operand_equal_p (TREE_OPERAND (stmt, 0),
TREE_OPERAND (use_stmt, 0), 0))
TREE_OPERAND (use_stmt, 0), 0)
&& memory_address_same (stmt, use_stmt))
{
/* Make sure we propagate the ABNORMAL bit setting. */
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (first_use_p)))