Stop print_hex from printing bits above the precision

2017-10-26  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* wide-int-print.cc (print_hex): Loop based on extract_uhwi.
	Don't print any bits outside the precision of the value.
	* wide-int.cc (test_printing): Add some new tests.

From-SVN: r254109

gcc/ChangeLog

+2017-10-26  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	* wide-int-print.cc (print_hex): Loop based on extract_uhwi.
+	Don't print any bits outside the precision of the value.
+	* wide-int.cc (test_printing): Add some new tests.
+
 2017-10-26  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* configure.ac (gcc_cv_as_ix86_xbrace_comment): Check if assembler

gcc/wide-int-print.cc

@@ -103,30 +103,28 @@ print_decu (const wide_int_ref &wi, FILE *file)
 }
 
 void
-print_hex (const wide_int_ref &wi, char *buf)
+print_hex (const wide_int_ref &val, char *buf)
 {
-  int i = wi.get_len ();
-
-  if (wi == 0)
+  if (val == 0)
     buf += sprintf (buf, "0x0");
   else
     {
-      if (wi::neg_p (wi))
+      buf += sprintf (buf, "0x");
+      int start = ROUND_DOWN (val.get_precision (), HOST_BITS_PER_WIDE_INT);
+      int width = val.get_precision () - start;
+      bool first_p = true;
+      for (int i = start; i >= 0; i -= HOST_BITS_PER_WIDE_INT)
 	{
-	  int j;
-	  /* If the number is negative, we may need to pad value with
-	     0xFFF...  because the leading elements may be missing and
-	     we do not print a '-' with hex.  */
-	  buf += sprintf (buf, "0x");
-	  for (j = BLOCKS_NEEDED (wi.get_precision ()); j > i; j--)
-	    buf += sprintf (buf, HOST_WIDE_INT_PRINT_PADDED_HEX, HOST_WIDE_INT_M1);
-
+	  unsigned HOST_WIDE_INT uhwi = wi::extract_uhwi (val, i, width);
+	  if (!first_p)
+	    buf += sprintf (buf, HOST_WIDE_INT_PRINT_PADDED_HEX, uhwi);
+	  else if (uhwi != 0)
+	    {
+	      buf += sprintf (buf, HOST_WIDE_INT_PRINT_HEX_PURE, uhwi);
+	      first_p = false;
+	    }
+	  width = HOST_BITS_PER_WIDE_INT;
 	}
-      else
-	buf += sprintf (buf, "0x" HOST_WIDE_INT_PRINT_HEX_PURE, wi.elt (--i));
-
-      while (--i >= 0)
-	buf += sprintf (buf, HOST_WIDE_INT_PRINT_PADDED_HEX, wi.elt (i));
     }
 }
 

gcc/wide-int.cc

@@ -2253,6 +2253,17 @@ test_printing ()
   VALUE_TYPE a = from_int<VALUE_TYPE> (42);
   assert_deceq ("42", a, SIGNED);
   assert_hexeq ("0x2a", a);
+  assert_hexeq ("0x1fffffffffffffffff", wi::shwi (-1, 69));
+  assert_hexeq ("0xffffffffffffffff", wi::mask (64, false, 69));
+  assert_hexeq ("0xffffffffffffffff", wi::mask <widest_int> (64, false));
+  if (WIDE_INT_MAX_PRECISION > 128)
+    {
+      assert_hexeq ("0x20000000000000000fffffffffffffffe",
+		    wi::lshift (1, 129) + wi::lshift (1, 64) - 2);
+      assert_hexeq ("0x200000000000004000123456789abcdef",
+		    wi::lshift (1, 129) + wi::lshift (1, 74)
+		    + wi::lshift (0x1234567, 32) + 0x89abcdef);
+    }
 }
 
 /* Verify that various operations work correctly for VALUE_TYPE,