tree-ssa-dse: Fix up go.test/test/fixedbugs/issue16095.go miscompilation [PR100382]

The new DCE code inside of tree DSE removes in -fnon-call-exceptions
go code a load from NULL pointer the testcase relies on throwing an
exception and so the test hangs.

The following patch just repeats a check that e.g. tree-ssa-dce.c
uses to prevent this.

2021-05-03  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/100382
	* tree-ssa-dse.c: Include tree-eh.h.
	(dse_dom_walker::before_dom_children): Don't remove stmts if
	stmt_unremovable_because_of_non_call_eh_p is true.

diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index aecf6ab..76929fa 100644 (file)
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "builtins.h"
 #include "gimple-fold.h"
 #include "gimplify.h"
+#include "tree-eh.h"
 
 /* This file implements dead store elimination.
 
@@ -1193,7 +1194,8 @@ dse_dom_walker::before_dom_children (basic_block bb)
          /* When we remove dead stores make sure to also delete trivially
             dead SSA defs.  */
          if (has_zero_uses (DEF_FROM_PTR (def_p))
-             && !gimple_has_side_effects (stmt))
+             && !gimple_has_side_effects (stmt)
+             && !stmt_unremovable_because_of_non_call_eh_p (cfun, stmt))
            {
              if (dump_file && (dump_flags & TDF_DETAILS))
                {