tree-inline: Fix a -fcompare-debug issue in the inliner [PR94167]

The following testcase fails with -fcompare-debug.  The problem is that
bar is marked as address_taken only with -g and not without.
I've tracked it down to insert_init_stmt calling gimple_regimplify_operands
even on DEBUG_STMTs.  That function will just insert normal stmts before
the DEBUG_STMT if the DEBUG_STMT operand isn't gimple val or invariant.
While DCE will turn those statements into debug temporaries, it can cause
differences in SSA_NAMEs and more importantly, the ipa references are
generated from those before the DCE happens.
On the testcase, the DEBUG_STMT value is (int)bar.

We could generate DEBUG_STMTs with debug temporaries instead, but I fail to
see the reason to do that, DEBUG_STMTs allow other expressions and all we
want to ensure is that the expressions aren't too large (arbitrarily
complex), but during inlining/function versioning I don't see why something
would queue a DEBUG_STMT with arbitrarily complex expressions in there.

2020-03-16  Jakub Jelinek  <jakub@redhat.com>

	PR debug/94167
	* tree-inline.c (insert_init_stmt): Don't gimple_regimplify_operands
	DEBUG_STMTs.

	* gcc.dg/pr94167.c: New test.

1 files changed, 2 insertions, 2 deletions

diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index 59798ec0454..f095795f06f 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -3361,10 +3361,10 @@ insert_init_stmt (copy_body_data *id, basic_block bb, gimple *init_stmt)
 	  gimple_assign_set_rhs1 (init_stmt, rhs);
 	}
       gsi_insert_after (&si, init_stmt, GSI_NEW_STMT);
-      gimple_regimplify_operands (init_stmt, &si);
-
       if (!is_gimple_debug (init_stmt))
 	{
+	  gimple_regimplify_operands (init_stmt, &si);
+
 	  tree def = gimple_assign_lhs (init_stmt);
 	  insert_init_debug_bind (id, bb, def, def, init_stmt);
 	}