re PR rtl-optimization/67736 (Wrong optimization with -fexpensive-optimizations on mips64el)

2015-10-23  Steve Ellcey  <sellcey@imgtec.com>
	    Andrew Pinski  <apinski@cavium.com>

	PR rtl-optimization/67736
	* combine.c (simplify_comparison): Use gen_lowpart_or_truncate instead
	of gen_lowpart.

Co-Authored-By: Andrew Pinski <apinski@cavium.com>

From-SVN: r229259

gcc/ChangeLog

+2015-10-23  Steve Ellcey  <sellcey@imgtec.com>
+	    Andrew Pinski  <apinski@cavium.com>
+
+	PR rtl-optimization/67736
+	* combine.c (simplify_comparison): Use gen_lowpart_or_truncate instead
+	of gen_lowpart.
+
 2015-10-23  Ilya Enkovich  <enkovich.gnu@gmail.com>
 
 	PR middle-end/68066

gcc/combine.c

@@ -11530,8 +11530,8 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
 		 tmode != GET_MODE (op0); tmode = GET_MODE_WIDER_MODE (tmode))
 	      if ((unsigned HOST_WIDE_INT) c0 == GET_MODE_MASK (tmode))
 		{
-		  op0 = gen_lowpart (tmode, inner_op0);
-		  op1 = gen_lowpart (tmode, inner_op1);
+		  op0 = gen_lowpart_or_truncate (tmode, inner_op0);
+		  op1 = gen_lowpart_or_truncate (tmode, inner_op1);
 		  code = unsigned_condition (code);
 		  changed = 1;
 		  break;
@@ -12049,12 +12049,9 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
 				   & GET_MODE_MASK (mode))
 				  + 1)) >= 0
 	      && const_op >> i == 0
-	      && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode
-	      && (TRULY_NOOP_TRUNCATION_MODES_P (tmode, GET_MODE (op0))
-		  || (REG_P (XEXP (op0, 0))
-		      && reg_truncated_to_mode (tmode, XEXP (op0, 0)))))
+	      && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode)
 	    {
-	      op0 = gen_lowpart (tmode, XEXP (op0, 0));
+	      op0 = gen_lowpart_or_truncate (tmode, XEXP (op0, 0));
 	      continue;
 	    }