--- a/src/hotspot/share/utilities/globalDefinitions.hpp Thu Nov 07 11:34:01 2019 -0800
+++ b/src/hotspot/share/utilities/globalDefinitions.hpp Thu Nov 07 16:22:22 2019 -0500
@@ -1110,6 +1110,33 @@
#undef JAVA_INTEGER_OP
+// Provide integer shift operations with Java semantics. No overflow
+// issues - left shifts simply discard shifted out bits. No undefined
+// behavior for large or negative shift quantities; instead the actual
+// shift distance is the argument modulo the lhs value's size in bits.
+// No undefined or implementation defined behavior for shifting negative
+// values; left shift discards bits, right shift sign extends. We use
+// the same safe conversion technique as above for java_add and friends.
+#define JAVA_INTEGER_SHIFT_OP(OP, NAME, TYPE, XTYPE) \
+inline TYPE NAME (TYPE lhs, jint rhs) { \
+ const uint rhs_mask = (sizeof(TYPE) * 8) - 1; \
+ STATIC_ASSERT(rhs_mask == 31 || rhs_mask == 63); \
+ XTYPE xres = static_cast<XTYPE>(lhs); \
+ xres OP ## = (rhs & rhs_mask); \
+ return reinterpret_cast<TYPE&>(xres); \
+}
+
+JAVA_INTEGER_SHIFT_OP(<<, java_shift_left, jint, juint)
+JAVA_INTEGER_SHIFT_OP(<<, java_shift_left, jlong, julong)
+// For signed shift right, assume C++ implementation >> sign extends.
+JAVA_INTEGER_SHIFT_OP(>>, java_shift_right, jint, jint)
+JAVA_INTEGER_SHIFT_OP(>>, java_shift_right, jlong, jlong)
+// For >>> use C++ unsigned >>.
+JAVA_INTEGER_SHIFT_OP(>>, java_shift_right_unsigned, jint, juint)
+JAVA_INTEGER_SHIFT_OP(>>, java_shift_right_unsigned, jlong, julong)
+
+#undef JAVA_INTEGER_SHIFT_OP
+
//----------------------------------------------------------------------------------------------------
// The goal of this code is to provide saturating operations for int/uint.
// Checks overflow conditions and saturates the result to min_jint/max_jint.