> probably also helps PR109612 and the other similar PR referenced therein.

Here's a more aggressive patch in this area, but it regresses guality tests, 
for example:

+FAIL: gcc.dg/guality/ipa-sra-1.c   -O2  -DPREVENT_OPTIMIZATION  line 27 k == 
3
+FAIL: gcc.dg/guality/ipa-sra-1.c   -O3 -g  -DPREVENT_OPTIMIZATION  line 27 k 
== 3
+FAIL: gcc.dg/guality/ipa-sra-1.c   -Os  -DPREVENT_OPTIMIZATION  line 27 k == 
3

eric@fomalhaut:~/build/gcc/native> diff -u ipa-sra-1.c.254t.optimized.0 ipa-
sra-1.c.254t.optimized
--- ipa-sra-1.c.254t.optimized.0        2023-04-26 11:12:07.806357325 +0200
+++ ipa-sra-1.c.254t.optimized  2023-04-26 11:24:08.632874257 +0200
@@ -101,7 +101,6 @@
   # DEBUG k => k_5
   # DEBUG BEGIN_STMT
   _1 = get_val1 ();
-  # DEBUG D#6 => k_5
   r_8 = foo.isra (_1);
   # DEBUG r => r_8
   # DEBUG BEGIN_STMT

and I don't understand why yet.


	* tree-ssa-dce.cc (find_debug_expr_decl): New callback.
	(mark_stmt_if_obviously_necessary): Add DECLS parameters.
	<GIMPLE_DEBUG>: Call find_debug_expr_decl on the value of
	DEBUG_BIND statements and record the results in DECLS.
	(find_obviously_necessary_stmts): If DEBUG_BIND statements may be
	present, get rid of those setting an unnecessary DEBUG_EXPR_DECL.

-- 
Eric Botcazou