re PR debug/49522 (Divide by zero in validate_subreg in emit-rtl.c:695)

	PR debug/49522
	* df-problems.c (dead_debug_reset): Remove dead_debug_uses
	referencing debug insns that have been reset.
	(dead_debug_insert_before): Don't assert reg is non-NULL,
	instead return immediately if it is NULL.

	* gcc.dg/debug/pr49522.c: New test.


M    gcc/ChangeLog
A    gcc/testsuite/gcc.dg/debug/pr49522.c
M    gcc/testsuite/ChangeLog
M    gcc/df-problems.c

From-SVN: r175987

4 files changed, 76 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c19bef8..88b0d81 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2011-07-07  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/49522
+	* df-problems.c (dead_debug_reset): Remove dead_debug_uses
+	referencing debug insns that have been reset.
+	(dead_debug_insert_before): Don't assert reg is non-NULL,
+	instead return immediately if it is NULL.
+
 2011-07-07  Joseph Myers  <joseph@codesourcery.com>
 
 	* config/i386/t-crtpic, config/i386/t-svr3dbx, config/pa/t-pa:
diff --git a/gcc/df-problems.c b/gcc/df-problems.c
index 59bed8b..e547b67 100644
--- a/gcc/df-problems.c
+++ b/gcc/df-problems.c
@@ -3096,6 +3096,7 @@ static void
 dead_debug_reset (struct dead_debug *debug, unsigned int dregno)
 {
   struct dead_debug_use **tailp = &debug->head;
+  struct dead_debug_use **insnp = &debug->head;
   struct dead_debug_use *cur;
   rtx insn;
 
@@ -3113,9 +3114,25 @@ dead_debug_reset (struct dead_debug *debug, unsigned int dregno)
 	    debug->to_rescan = BITMAP_ALLOC (NULL);
 	  bitmap_set_bit (debug->to_rescan, INSN_UID (insn));
 	  XDELETE (cur);
+	  /* If the current use isn't the first one attached to INSN, go back
+	     to this first use.  We assume that the uses attached to an insn
+	     are adjacent.  */                                                                       
+	  if (tailp != insnp && DF_REF_INSN ((*insnp)->use) == insn)
+	    tailp = insnp;
+	  /* Then remove all the other uses attached to INSN.  */
+	  while ((cur = *tailp) && DF_REF_INSN (cur->use) == insn)
+	    {
+	      *tailp = cur->next;
+	      XDELETE (cur);
+	    }
+	  insnp = tailp;
 	}
       else
-	tailp = &(*tailp)->next;
+	{
+	  if (DF_REF_INSN ((*insnp)->use) != DF_REF_INSN (cur->use))
+	    insnp = tailp;
+	  tailp = &(*tailp)->next;
+	}
     }
 }
 
@@ -3174,7 +3191,10 @@ dead_debug_insert_before (struct dead_debug *debug, unsigned int uregno,
 	tailp = &(*tailp)->next;
     }
 
-  gcc_assert (reg);
+  /* We may have dangling bits in debug->used for registers that were part
+     of a multi-register use, one component of which has been reset.  */
+  if (reg == NULL)
+    return;
 
   /* Create DEBUG_EXPR (and DEBUG_EXPR_DECL).  */
   dval = make_debug_expr_from_rtl (reg);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ea8d6f8..c54bd86 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2011-07-07  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/49522
+	* gcc.dg/debug/pr49522.c: New test.
+
 2011-07-07  Georg-Johann Lay  <avr@gjlay.de>
 	
 	* gcc.dg/pragma-align.c: Run only if target !default_packed.
diff --git a/gcc/testsuite/gcc.dg/debug/pr49522.c b/gcc/testsuite/gcc.dg/debug/pr49522.c
new file mode 100644
index 0000000..3fa3bfb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/pr49522.c
@@ -0,0 +1,41 @@
+/* PR debug/49522 */
+/* { dg-do compile } */
+/* { dg-options "-fcompare-debug" } */
+
+int val1 = 0L;
+volatile int val2 = 7L;
+long long val3;
+int *ptr = &val1;
+
+static int
+func1 ()
+{
+  return 0;
+}
+
+static short int
+func2 (short int a, unsigned int b)
+{
+  return !b ? a : a >> b;
+}
+
+static unsigned long long
+func3 (unsigned long long a, unsigned long long b)
+{
+  return !b ? a : a % b;
+}
+
+void
+func4 (unsigned short arg1, int arg2)
+{
+  for (arg2 = 0; arg2 < 2; arg2++)
+    {
+      *ptr = func3 (func3 (10, func2 (val3, val2)), val3);
+      for (arg1 = -14; arg1 > 14; arg1 = func1 ())
+	{
+	  *ptr = -1;
+	  if (foo ())
+	    ;
+	}
+    }
+}