--- a/hotspot/src/share/vm/utilities/globalDefinitions.cpp Wed Mar 09 15:37:33 2016 -0800
+++ b/hotspot/src/share/vm/utilities/globalDefinitions.cpp Thu Feb 25 13:08:19 2016 +0100
@@ -358,6 +358,20 @@
return size_t(result);
}
+
+// Test that nth_bit macro and friends behave as
+// expected, even with low-precedence operators.
+
+STATIC_ASSERT(nth_bit(3) == 0x8);
+STATIC_ASSERT(nth_bit(1|2) == 0x8);
+
+STATIC_ASSERT(right_n_bits(3) == 0x7);
+STATIC_ASSERT(right_n_bits(1|2) == 0x7);
+
+STATIC_ASSERT(left_n_bits(3) == (intptr_t) LP64_ONLY(0xE000000000000000) NOT_LP64(0xE0000000));
+STATIC_ASSERT(left_n_bits(1|2) == (intptr_t) LP64_ONLY(0xE000000000000000) NOT_LP64(0xE0000000));
+
+
#ifndef PRODUCT
// For unit testing only
class GlobalDefinitions {
--- a/hotspot/src/share/vm/utilities/globalDefinitions.hpp Wed Mar 09 15:37:33 2016 -0800
+++ b/hotspot/src/share/vm/utilities/globalDefinitions.hpp Thu Feb 25 13:08:19 2016 +0100
@@ -1083,9 +1083,9 @@
// get a word with the n.th or the right-most or left-most n bits set
// (note: #define used only so that they can be used in enum constant definitions)
-#define nth_bit(n) (n >= BitsPerWord ? 0 : OneBit << (n))
+#define nth_bit(n) (((n) >= BitsPerWord) ? 0 : (OneBit << (n)))
#define right_n_bits(n) (nth_bit(n) - 1)
-#define left_n_bits(n) (right_n_bits(n) << (n >= BitsPerWord ? 0 : (BitsPerWord - n)))
+#define left_n_bits(n) (right_n_bits(n) << (((n) >= BitsPerWord) ? 0 : (BitsPerWord - (n))))
// bit-operations using a mask m
inline void set_bits (intptr_t& x, intptr_t m) { x |= m; }