Convert V1TImode register to TImode in debug insn

TImode register referenced in debug insn can be converted to V1TImode by
scalar to vector optimization.  When converting a TImode store to V1TImode,
we need to check all debug insns on its use chain to convert the V1TImode
register to SUBREG TImode if source register is undefined.

gcc/

	PR target/72748
	* config/i386/i386.c (timode_scalar_chain::convert_insn): Call
	fix_debug_reg_uses after changing source register mode to
	V1TImode if source register is undefined.

gcc/testsuite/

	PR target/72748
	* gcc.target/i386/pr72748.c: New test.

From-SVN: r238956

gcc/ChangeLog

+2015-08-01  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/72748
+	* config/i386/i386.c (timode_scalar_chain::convert_insn): Call
+	fix_debug_reg_uses after changing source register mode to
+	V1TImode if source register is undefined.
+
 2015-08-01  Alan Hayward <alan.hayward@arm.com>
 
 	PR tree-optimization/71818

gcc/config/i386/i386.c

@@ -3858,6 +3858,12 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
   switch (GET_CODE (src))
     {
     case REG:
+      PUT_MODE (src, V1TImode);
+      /* Call fix_debug_reg_uses only if SRC is never defined.  */
+      if (!DF_REG_DEF_CHAIN (REGNO (src)))
+	fix_debug_reg_uses (src);
+      break;
+
     case MEM:
       PUT_MODE (src, V1TImode);
       break;

gcc/testsuite/ChangeLog

+2015-08-01  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR target/72748
+	* gcc.target/i386/pr72748.c: New test.
+
 2015-08-01  Alan Hayward <alan.hayward@arm.com>
 
 	PR tree-optimization/71818

gcc/testsuite/gcc.target/i386/pr72748.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -g" } */
+
+volatile int a;
+int c, d, e, f, g, h;
+
+int fn1 ()
+{ 
+  int i;
+  for (; d;)
+    { 
+      if (e)
+        break;
+      g = 0;
+      int j[4];
+      for (h = 0; h < 4; h++)
+        g++;
+      for (; c < 2; c++)
+        { 
+          e = j[g];
+          i = j[0];
+          f = 4;
+        }
+      f |= d;
+    }
+  return a;
+}