ipa/100373 - fix emutls lowering compare-debug issue

emutls figured that tls uses in debug-insns need lowering but
that obviously has effects on code-generation as can be seen
in the following IL diff with the new testcase:

   <bb 2> [local count: 1073741824]:
-  a = 0;
+  # DEBUG BEGIN_STMT
   _4 = __builtin___emutls_get_address (&__emutls_v.b);
+  # DEBUG D#1 => *_4
+  # DEBUG d => (long int) D#1
+  # DEBUG BEGIN_STMT
+  a = 0;
+  # DEBUG BEGIN_STMT
   *_4 = 0;
   return;

where it figured the debug use of b in the original

  <bb 2> [local count: 1073741824]:
  # DEBUG BEGIN_STMT
  # DEBUG D#1 => b
  # DEBUG d => (long int) D#1
  # DEBUG BEGIN_STMT
  a = 0;

needs lowering (it maybe does when we want to produce perfect
debug but that's just bad luck).

The following patch fixes this by avoiding to create a new
emutls address when visiting debug stmts and instead resets them.
Another option might be to simply not lower debug stmt uses
but I have no way to verify actual debug info for this.

2021-05-05  Richard Biener  <rguenther@suse.de>

	PR ipa/100373
	* tree-emutls.c (gen_emutls_addr): Pass in whether we're
	dealing with a debug use and only query existing addresses
	if so.
	(lower_emutls_1): Avoid splitting out addresses for debug
	stmts, reset the debug stmt when we fail to find existing
	lowered addresses.
	(lower_emutls_phi_arg): Set wi.stmt.

	* gcc.dg/pr100373.c: New testcase.

0 files changed, 0 insertions, 0 deletions