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tree-optimization/106378 - DSE of LEN_STORE and MASK_STORE

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The following enhances DSE to handle LEN_STORE (optimally) and
MASK_STORE (conservatively).

	PR tree-optimization/106378
	* tree-ssa-dse.cc (initialize_ao_ref_for_dse): Handle
	LEN_STORE, add mode to initialize a may-def and handle
	MASK_STORE that way.
	(dse_optimize_stmt): Query may-defs.  Handle internal
	functions LEN_STORE and MASK_STORE similar to how
	we handle memory builtins but without byte tracking.
This commit is contained in:
Richard Biener 2022-07-21 10:13:46 +02:00
parent bd9837bc3c
commit dc477ffb4a
1 changed files with 51 additions and 4 deletions
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55
gcc/tree-ssa-dse.cc
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@ -93,7 +93,9 @@ static bitmap need_eh_cleanup;
static bitmap need_ab_cleanup;
/* STMT is a statement that may write into memory. Analyze it and
initialize WRITE to describe how STMT affects memory.
initialize WRITE to describe how STMT affects memory. When
MAY_DEF_OK is true then the function initializes WRITE to what
the stmt may define.
Return TRUE if the statement was analyzed, FALSE otherwise.
@ -101,7 +103,7 @@ static bitmap need_ab_cleanup;
can be achieved by analyzing more statements. */
static bool
initialize_ao_ref_for_dse (gimple *stmt, ao_ref *write)
initialize_ao_ref_for_dse (gimple *stmt, ao_ref *write, bool may_def_ok = false)
{
/* It's advantageous to handle certain mem* functions. */
if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
@ -146,6 +148,32 @@ initialize_ao_ref_for_dse (gimple *stmt, ao_ref *write)
break;
}
}
else if (is_gimple_call (stmt)
&& gimple_call_internal_p (stmt))
{
switch (gimple_call_internal_fn (stmt))
{
case IFN_LEN_STORE:
ao_ref_init_from_ptr_and_size
(write, gimple_call_arg (stmt, 0),
int_const_binop (MINUS_EXPR,
gimple_call_arg (stmt, 2),
gimple_call_arg (stmt, 4)));
return true;
case IFN_MASK_STORE:
/* We cannot initialize a must-def ao_ref (in all cases) but we
can provide a may-def variant. */
if (may_def_ok)
{
ao_ref_init_from_ptr_and_size
(write, gimple_call_arg (stmt, 0),
TYPE_SIZE_UNIT (TREE_TYPE (gimple_call_arg (stmt, 2))));
return true;
}
break;
default:;
}
}
else if (tree lhs = gimple_get_lhs (stmt))
{
if (TREE_CODE (lhs) != SSA_NAME)
@ -1328,8 +1356,10 @@ dse_optimize_stmt (function *fun, gimple_stmt_iterator *gsi, sbitmap live_bytes)
ao_ref ref;
/* If this is not a store we can still remove dead call using
modref summary. */
if (!initialize_ao_ref_for_dse (stmt, &ref))
modref summary. Note we specifically allow ref to be initialized
to a conservative may-def since we are looking for followup stores
to kill all of it. */
if (!initialize_ao_ref_for_dse (stmt, &ref, true))
{
dse_optimize_call (gsi, live_bytes);
return;
@ -1398,6 +1428,23 @@ dse_optimize_stmt (function *fun, gimple_stmt_iterator *gsi, sbitmap live_bytes)
return;
}
}
else if (is_gimple_call (stmt)
&& gimple_call_internal_p (stmt))
{
switch (gimple_call_internal_fn (stmt))
{
case IFN_LEN_STORE:
case IFN_MASK_STORE:
{
enum dse_store_status store_status;
store_status = dse_classify_store (&ref, stmt, false, live_bytes);
if (store_status == DSE_STORE_DEAD)
delete_dead_or_redundant_call (gsi, "dead");
return;
}
default:;
}
}
bool by_clobber_p = false;