Hi! Based on IRC discussions, I've added another test with __GIMPLE next to the one with -fno-tree-dse.
2020-02-26 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/93820 * gcc.dg/pr93820-2.c: New test. --- gcc/testsuite/gcc.dg/pr93820-2.c.jj 2020-02-26 10:50:18.796137652 +0100 +++ gcc/testsuite/gcc.dg/pr93820-2.c 2020-02-26 10:51:14.833310929 +0100 @@ -0,0 +1,30 @@ +/* PR tree-optimization/93820 */ +/* { dg-do run } */ +/* { dg-options "-O2 -fgimple" } */ + +typedef int v4si __attribute__((vector_size(4 * sizeof (int)))); +int a[10]; + +void __GIMPLE (ssa,startwith("store-merging")) +foo (int *p) +{ + int _2; + __BB(2): + _2 = *p_1(D); + a[6] = _2; + a[4] = 1; + __MEM <v4si> ((int *)&a + _Literal (int *) 16) = _Literal (v4si) { 0, 0, 0, 0 }; + a[3] = 0; + return; +} + +int +main () +{ + int i = 0; + foo (&i); + for (i = 0; i < 10; i++) + if (a[i]) + __builtin_abort (); + return 0; +} Jakub