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[PATCH] Fix valtrack ICE (PR debug/53923)


Hi!

On the testcase from this PR on AVR (from libgcc, thus not including
it into testsuite/) we ICE, because dead_debug_insert_temp is called
several times on the same insn, for multi-register hard register for each
regno in it (except the first which doesn't seem to be dead).
In the first call dead_debug_insert_temp changes *DF_REF_REAL_LOC
to DEBUG_EXPR, and in the next call for the next consecutive hard register
we set reg variable to *DF_REF_REAL_LOC and rely on it to be a REG,
when it is a DEBUG_EXPR already instead.  No change is needed in that case.

Bootstrapped/regtested on x86_64-linux and i686-linux (where this never
kicks in though), tested on the testcase in cross to avr.  Ok for trunk?

2012-08-20  Jakub Jelinek  <jakub@redhat.com>

	PR debug/53923
	* valtrack.c (dead_debug_insert_temp): Drop non-reg uses
	from the chain.

--- gcc/valtrack.c.jj	2012-08-10 12:57:21.000000000 +0200
+++ gcc/valtrack.c	2012-08-20 14:59:07.609586159 +0200
@@ -336,6 +336,14 @@ dead_debug_insert_temp (struct dead_debu
     {
       if (DF_REF_REGNO (cur->use) == uregno)
 	{
+	  /* If this loc has been changed e.g. to debug_expr already
+	     as part of a multi-register use, just drop it.  */
+	  if (!REG_P (*DF_REF_REAL_LOC (cur->use)))
+	    {
+	      *tailp = cur->next;
+	      XDELETE (cur);
+	      continue;
+	    }
 	  *usesp = cur;
 	  usesp = &cur->next;
 	  *tailp = cur->next;

	Jakub


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