The following enhances DSE to handle LEN_STORE (optimally) and
MASK_STORE (conservatively).
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Kewen is testing on powerpc. Handling MASK_STORE_LANES in
a similar way to MASK_STORE is probably possible but I couldn't
figure a way to generate one for testing. STORE_LANES is
probably handled already since it's ECF_CONST.
PR tree-optimization/106365
* 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.
---
gcc/tree-ssa-dse.cc | 55 +++++++++++++++++++++++++++++++++++++++++----
1 file changed, 51 insertions(+), 4 deletions(-)
diff --git a/gcc/tree-ssa-dse.cc b/gcc/tree-ssa-dse.cc
index 8d1739a4510..34cfd1a8802 100644
--- a/gcc/tree-ssa-dse.cc
+++ b/gcc/tree-ssa-dse.cc
@@ -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;
--
2.35.3
