DSE: Add LEN_MASK_STORE analysis into DSE and fix LEN_STORE

Hi, Richi.

This patch is adding LEN_MASK_STORE into DSE.

My understanding is LEN_MASK_STORE is predicated by mask and len.
No matter len is constant or not, the ao_ref should be the same as MASK_STORE.

Wheras for LEN_STORE, when len is constant, we use (len - bias), otherwise, it's
the same as MASK_STORE/LEN_MASK_STORE.

Not sure whether I am on the same page with you, feel free to correct me.

Thanks.

gcc/ChangeLog:

	* tree-ssa-dse.cc (initialize_ao_ref_for_dse): Add LEN_MASK_STORE and
	fix LEN_STORE.
	(dse_optimize_stmt): Add LEN_MASK_STORE.

diff --git a/gcc/tree-ssa-dse.cc b/gcc/tree-ssa-dse.cc
index 3c7a2e9992d767afb2d748e08e1cc27ec50f7cd8..f8338037a6110de2716bfe6dd16ef6cc623eb9c5 100644 (file)
--- a/gcc/tree-ssa-dse.cc
+++ b/gcc/tree-ssa-dse.cc
@@ -48,6 +48,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssa-loop-niter.h"
 #include "cfgloop.h"
 #include "tree-data-ref.h"
+#include "internal-fn.h"
 
 /* This file implements dead store elimination.
 
@@ -157,23 +158,36 @@ initialize_ao_ref_for_dse (gimple *stmt, ao_ref *write, bool may_def_ok = false)
       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, 3))));
-             return true;
-           }
-         break;
+       case IFN_LEN_MASK_STORE:
+         {
+           int stored_value_index
+             = internal_fn_stored_value_index (gimple_call_internal_fn (stmt));
+           if (gimple_call_internal_fn (stmt) == IFN_LEN_STORE)
+             {
+               tree len = gimple_call_arg (stmt, 2);
+               tree bias = gimple_call_arg (stmt, 4);
+               if (tree_fits_uhwi_p (len))
+                 {
+                   ao_ref_init_from_ptr_and_size (write,
+                                                  gimple_call_arg (stmt, 0),
+                                                  int_const_binop (MINUS_EXPR,
+                                                                   len, bias));
+                   return true;
+                 }
+             }
+           /* 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, stored_value_index))));
+               return true;
+             }
+           break;
+         }
        default:;
        }
     }
@@ -1502,6 +1516,7 @@ dse_optimize_stmt (function *fun, gimple_stmt_iterator *gsi, sbitmap live_bytes)
        {
        case IFN_LEN_STORE:
        case IFN_MASK_STORE:
+       case IFN_LEN_MASK_STORE:
          {
            enum dse_store_status store_status;
            store_status = dse_classify_store (&ref, stmt, false, live_bytes);