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[PR 50826] [DF] no debug temps for artificial uses

This patch is a small improvement to DF, for an issue I noticed while
investigating PR 50826.  We take note of, and may emit debug temps for,
REGs for which we won't emit REG_DEAD/REG_UNUSED notes.  This is a
waste, removed with this patch.

Regstrapped on x86_64-linux-gnu and i686-linux-gnu.  Ok to install?

for  gcc/ChangeLog
from  Alexandre Oliva  <>

	PR debug/50826
	* df-problems.c (df_note_bb_compute): Do not take note of
	debug uses for whose REGs we won't emit DEAD or UNUSED notes.
Index: gcc/df-problems.c
--- gcc/df-problems.c.orig	2012-04-08 01:50:45.379141149 -0300
+++ gcc/df-problems.c	2012-04-08 02:05:13.406574358 -0300
@@ -3528,7 +3528,12 @@ df_note_bb_compute (unsigned int bb_inde
 		  if (debug_insn > 0)
-		      dead_debug_add (&debug, use, uregno);
+		      /* We won't add REG_UNUSED or REG_DEAD notes for
+			 these, so we don't have to mess with them in
+			 debug insns either.  */
+		      if (!bitmap_bit_p (artificial_uses, uregno)
+			  && (!df_ignore_stack_reg (uregno)))
+			dead_debug_add (&debug, use, uregno);

Alexandre Oliva, freedom fighter
You must be the change you wish to see in the world. -- Gandhi
Be Free! --   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer

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