8233364: Fix undefined behavior in Canonicalizer::do_ShiftOp

Add java_shift_xxx helpers and use them.

Reviewed-by: sgehwolf, roland
Backport-of: 89e3782f218a54c91cbab9f06e75825b90dd2fb7

Author: martinuy

hotspot/src/share/vm/c1/c1_Canonicalizer.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -303,24 +303,20 @@ void Canonicalizer::do_ShiftOp        (ShiftOp*         x) {
     }
     if (t2->is_constant()) {
       if (t->tag() == intTag) {
-        int value = t->as_IntConstant()->value();
-        int shift = t2->as_IntConstant()->value() & 31;
-        jint mask = ~(~0 << (32 - shift));
-        if (shift == 0) mask = ~0;
+        jint value = t->as_IntConstant()->value();
+        jint shift = t2->as_IntConstant()->value();
         switch (x->op()) {
-          case Bytecodes::_ishl:  set_constant(value << shift); return;
-          case Bytecodes::_ishr:  set_constant(value >> shift); return;
-          case Bytecodes::_iushr: set_constant((value >> shift) & mask); return;
+          case Bytecodes::_ishl:  set_constant(java_shift_left(value, shift)); return;
+          case Bytecodes::_ishr:  set_constant(java_shift_right(value, shift)); return;
+          case Bytecodes::_iushr: set_constant(java_shift_right_unsigned(value, shift)); return;
         }
       } else if (t->tag() == longTag) {
         jlong value = t->as_LongConstant()->value();
-        int shift = t2->as_IntConstant()->value() & 63;
-        jlong mask = ~(~jlong_cast(0) << (64 - shift));
-        if (shift == 0) mask = ~jlong_cast(0);
+        jint shift = t2->as_IntConstant()->value();
         switch (x->op()) {
-          case Bytecodes::_lshl:  set_constant(value << shift); return;
-          case Bytecodes::_lshr:  set_constant(value >> shift); return;
-          case Bytecodes::_lushr: set_constant((value >> shift) & mask); return;
+          case Bytecodes::_lshl:  set_constant(java_shift_left(value, shift)); return;
+          case Bytecodes::_lshr:  set_constant(java_shift_right(value, shift)); return;
+          case Bytecodes::_lushr: set_constant(java_shift_right_unsigned(value, shift)); return;
         }
       }
     }

hotspot/src/share/vm/utilities/globalDefinitions.hpp

@@ -1280,6 +1280,42 @@ inline intx byte_size(void* from, void* to) {
   return (address)to - (address)from;
 }
 
+#ifdef ASSERT
+#define RHS_MASK_ASSERT(rhs_mask)                       \
+  if (rhs_mask != 31 && rhs_mask != 63) {               \
+    basic_fatal("rhs_mask assertion failed.");          \
+  }
+#else
+#define RHS_MASK_ASSERT(rhs_mask)
+#endif
+
+// 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;         \
+  RHS_MASK_ASSERT(rhs_mask)                             \
+  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
+
 //----------------------------------------------------------------------------------------------------
 // Avoid non-portable casts with these routines (DEPRECATED)