re PR target/45336 (pextr{b,w,d}, (worse than) redundant extensions)

	PR target/45336
	* simplify-rtx.c (simplify_unary_operation_1): Optimize nested
	SIGN_EXTENDs or ZERO_EXTENDs.

From-SVN: r163384

gcc/ChangeLog

+2010-08-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/45336
+	* simplify-rtx.c (simplify_unary_operation_1): Optimize nested
+	SIGN_EXTENDs or ZERO_EXTENDs.
+
 2010-08-19  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR target/42172

gcc/simplify-rtx.c

@@ -1010,6 +1010,31 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
 	  && GET_MODE_SIZE (mode) <= GET_MODE_SIZE (GET_MODE (XEXP (op, 0))))
 	return rtl_hooks.gen_lowpart_no_emit (mode, op);
 
+      /* (sign_extend:M (sign_extend:N <X>)) is (sign_extend:M <X>).  */
+      if (GET_CODE (op) == SIGN_EXTEND)
+	return simplify_gen_unary (SIGN_EXTEND, mode, XEXP (op, 0),
+				   GET_MODE (XEXP (op, 0)));
+
+      /* (sign_extend:M (ashiftrt:N (ashift <X> (const_int I)) (const_int I)))
+	 is (sign_extend:M (subreg:O <X>)) if there is mode with
+	 GET_MODE_BITSIZE (N) - I bits.  */
+      if (GET_CODE (op) == ASHIFTRT
+	  && GET_CODE (XEXP (op, 0)) == ASHIFT
+	  && CONST_INT_P (XEXP (op, 1))
+	  && XEXP (XEXP (op, 0), 1) == XEXP (op, 1)
+	  && GET_MODE_BITSIZE (GET_MODE (op)) > INTVAL (XEXP (op, 1)))
+	{
+	  enum machine_mode tmode
+	    = mode_for_size (GET_MODE_BITSIZE (GET_MODE (op))
+			     - INTVAL (XEXP (op, 1)), MODE_INT, 1);
+	  if (tmode != BLKmode)
+	    {
+	      rtx inner =
+		rtl_hooks.gen_lowpart_no_emit (tmode, XEXP (XEXP (op, 0), 0));
+	      return simplify_gen_unary (SIGN_EXTEND, mode, inner, tmode);
+	    }
+	}
+
 #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend)
       /* As we do not know which address space the pointer is refering to,
 	 we can do this only if the target does not support different pointer
@@ -1036,6 +1061,11 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
 	  && GET_MODE_SIZE (mode) <= GET_MODE_SIZE (GET_MODE (XEXP (op, 0))))
 	return rtl_hooks.gen_lowpart_no_emit (mode, op);
 
+      /* (zero_extend:M (zero_extend:N <X>)) is (zero_extend:M <X>).  */
+      if (GET_CODE (op) == ZERO_EXTEND)
+	return simplify_gen_unary (ZERO_EXTEND, mode, XEXP (op, 0),
+				   GET_MODE (XEXP (op, 0)));
+
 #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend)
       /* As we do not know which address space the pointer is refering to,
 	 we can do this only if the target does not support different pointer