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.

gcc/ChangeLog

 2020-03-16  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/94167
+	* tree-inline.c (insert_init_stmt): Don't gimple_regimplify_operands
+	DEBUG_STMTs.
+
 	PR tree-optimization/94166
 	* tree-ssa-reassoc.c (sort_by_mach_mode): Use SSA_NAME_VERSION
 	as secondary comparison key.

gcc/testsuite/ChangeLog

 2020-03-16  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/94167
+	* gcc.dg/pr94167.c: New test.
+
 	PR tree-optimization/94166
 	* gcc.dg/pr94166.c: New test.
 

gcc/testsuite/gcc.dg/pr94167.c

+/* PR debug/94167 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcompare-debug" } */
+
+struct S { int g, h; signed char i; int j; signed char k; int l[4]; } a, c;
+struct T { signed char g; } e;
+int *b, d;
+static void foo ();
+
+void
+bar (void)
+{
+  while (d)
+    {
+      int k;
+      struct T f[3];
+      foo (bar, a);
+      for (k = 0;; k++)
+	f[k] = e;
+    }
+}
+
+static inline void
+foo (int x, struct S y, struct T z)
+{
+  for (z.g = 2; z.g; z.g--)
+    {
+      c = a = y;
+      *b |= 6;
+      if (y.g)
+	break;
+    }
+}

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);
 	}