src/hotspot/share/utilities/globalDefinitions.hpp

rev 56798 : [mq]: do_ShiftOp

*** 1108,1117 ****
--- 1108,1144 ----
  JAVA_INTEGER_OP(-, java_subtract, jlong, julong)
  JAVA_INTEGER_OP(*, java_multiply, jlong, julong)
  
  #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.
  #define SATURATED_INTEGER_OP(OP, NAME, TYPE1, TYPE2) \
  inline int NAME (TYPE1 in1, TYPE2 in2) {             \