diff mbox

Avoid extending lifetime of likely spilled hard regs in ifcvt before reload (PR rtl-optimization/56484)

Message ID 20130305223337.GN12913@tucnak.redhat.com
State New
Headers show

Commit Message

Jakub Jelinek March 5, 2013, 10:33 p.m. UTC 
On Tue, Mar 05, 2013 at 11:03:13PM +0100, Jakub Jelinek wrote:
> > ifcvt.c tests only small_register_classes_for_mode_p in the other places, so 
> > do you really need class_likely_spilled_p here?
> 
> I guess I don't.  I've grepped for small_register_classes_for_mode_p and didn't see
> anything in i386, so I figured out that it would be using a default (which
> is false).  But apparently it uses hook_bool_mode_true, so it is a superset
> of class_likely_spilled_p, guess I can leave that out.

Here is what I've actually committed (I've also removed the
!reload_completed &&, because noce_process_if_block is only called for
!!reload_completed (the only caller asserts it)).

2013-03-05  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/56484
	* ifcvt.c (noce_process_if_block): If else_bb is NULL, avoid extending
	lifetimes of hard registers on small register class machines.

	* gcc.c-torture/compile/pr56484.c: New test.



	Jakub
diff mbox

Patch

--- gcc/ifcvt.c.jj	2013-03-05 15:12:15.284564443 +0100
+++ gcc/ifcvt.c	2013-03-05 23:11:25.751625601 +0100
@@ -2491,6 +2491,12 @@  noce_process_if_block (struct noce_if_in
 	  || ! noce_operand_ok (SET_SRC (set_b))
 	  || reg_overlap_mentioned_p (x, SET_SRC (set_b))
 	  || modified_between_p (SET_SRC (set_b), insn_b, jump)
+	  /* Avoid extending the lifetime of hard registers on small
+	     register class machines.  */
+	  || (REG_P (SET_SRC (set_b))
+	      && HARD_REGISTER_P (SET_SRC (set_b))
+	      && targetm.small_register_classes_for_mode_p
+		   (GET_MODE (SET_SRC (set_b))))
 	  /* Likewise with X.  In particular this can happen when
 	     noce_get_condition looks farther back in the instruction
 	     stream than one might expect.  */
--- gcc/testsuite/gcc.c-torture/compile/pr56484.c.jj	2013-03-05 16:57:50.416961638 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr56484.c	2013-03-05 16:57:50.417961672 +0100
@@ -0,0 +1,17 @@ 
+/* PR rtl-optimization/56484 */
+
+unsigned char b[4096];
+int bar (void);
+
+int
+foo (void)
+{
+  int a = 0;
+  while (bar ())
+    {
+      int c = bar ();
+      a = a < 0 ? a : c;
+      __builtin_memset (b, 0, sizeof b);
+    }
+  return a;
+}