re PR rtl-optimization/78575 (ICE: in trunc_int_for_mode, at explow.c:55 with -O2 -g)

	PR rtl-optimization/78575
	* config/i386/i386.c (timode_scalar_chain::fix_debug_reg_uses): Use
	DF infrastructure to wrap all V1TImode reg uses into TImode subreg
	if not already wrapped in a subreg.  Make sure df_insn_rescan does not
	affect further iterations.

	* gcc.dg/pr78575.c: New test.

From-SVN: r243164

4 files changed, 49 insertions, 18 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4453842..a83f528 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2016-12-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/78575
+	* config/i386/i386.c (timode_scalar_chain::fix_debug_reg_uses): Use
+	DF infrastructure to wrap all V1TImode reg uses into TImode subreg
+	if not already wrapped in a subreg.  Make sure df_insn_rescan does not
+	affect further iterations.
+
 2016-12-02  Martin Liska  <mliska@suse.cz>
 
 	PR ipa/78555
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index a5f5339..5226e454 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -3831,30 +3831,32 @@ timode_scalar_chain::fix_debug_reg_uses (rtx reg)
   if (!flag_var_tracking)
     return;
 
-  df_ref ref;
-  for (ref = DF_REG_USE_CHAIN (REGNO (reg));
-       ref;
-       ref = DF_REF_NEXT_REG (ref))
+  df_ref ref, next;
+  for (ref = DF_REG_USE_CHAIN (REGNO (reg)); ref; ref = next)
     {
       rtx_insn *insn = DF_REF_INSN (ref);
+      /* Make sure the next ref is for a different instruction,
+         so that we're not affected by the rescan.  */
+      next = DF_REF_NEXT_REG (ref);
+      while (next && DF_REF_INSN (next) == insn)
+	next = DF_REF_NEXT_REG (next);
+
       if (DEBUG_INSN_P (insn))
 	{
 	  /* It may be a debug insn with a TImode variable in
 	     register.  */
-	  rtx val = PATTERN (insn);
-	  if (GET_MODE (val) != TImode)
-	    continue;
-	  gcc_assert (GET_CODE (val) == VAR_LOCATION);
-	  rtx loc = PAT_VAR_LOCATION_LOC (val);
-	  /* It may have been converted to TImode already.  */
-	  if (GET_MODE (loc) == TImode)
-	    continue;
-	  gcc_assert (REG_P (loc)
-		      && GET_MODE (loc) == V1TImode);
-	  /* Convert V1TImode register, which has been updated by a SET
-	     insn before, to SUBREG TImode.  */
-	  PAT_VAR_LOCATION_LOC (val) = gen_rtx_SUBREG (TImode, loc, 0);
-	  df_insn_rescan (insn);
+	  bool changed = false;
+	  for (; ref != next; ref = DF_REF_NEXT_REG (ref))
+	    {
+	      rtx *loc = DF_REF_LOC (ref);
+	      if (REG_P (*loc) && GET_MODE (*loc) == V1TImode)
+		{
+		  *loc = gen_rtx_SUBREG (TImode, *loc, 0);
+		  changed = true;
+		}
+	    }
+	  if (changed)
+	    df_insn_rescan (insn);
 	}
     }
 }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 14296a3..6ee4b13 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/78575
+	* gcc.dg/pr78575.c: New test.
+
 2016-12-02  Dominik Vogt  <vogt@linux.vnet.ibm.com>
 
 	* gcc.target/s390/litpool-r3-1.c: Fix label number test.
diff --git a/gcc/testsuite/gcc.dg/pr78575.c b/gcc/testsuite/gcc.dg/pr78575.c
new file mode 100644
index 0000000..6b27f10
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr78575.c
@@ -0,0 +1,16 @@
+/* PR rtl-optimization/78575 */
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -g -Wno-psabi" } */
+
+typedef unsigned __int128 V __attribute__((vector_size(64)));
+
+V g;
+
+void
+foo (V v)
+{
+  unsigned __int128 x = 1;
+  int c = v[1] <= ~x;
+  v &= v[1];
+  g = v;
+}