8257221: C2: RegMask::is_bound_set split set handling broken since JDK-8221404

Reviewed-by: kvn, neliasso

Author: cl4es

src/hotspot/share/opto/regmask.cpp

@@ -319,8 +319,8 @@ bool RegMask::is_bound_set(const unsigned int size) const {
         if ((all & ~(bit-1)) != _RM_UP[i])
           return false;         // Found many bits, so fail
         i++;                    // Skip iteration forward and check high part
-        // The lower (BitsPerWord - size) bits should be 1 since it is split case.
-        uintptr_t set = (bit >> (BitsPerWord - bit_index)) - 1;
+        // The lower bits should be 1 since it is split case.
+        uintptr_t set = (bit >> (BitsPerWord - size)) - 1;
         if (i > _hwm || _RM_UP[i] != set)
           return false; // Require expected low bits in next word
       }

test/hotspot/gtest/opto/test_regmask.cpp

@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "opto/opcodes.hpp"
 #include "opto/regmask.hpp"
 #include "unittest.hpp"
 
@@ -146,11 +147,52 @@ TEST_VM(RegMask, is_bound1) {
   ASSERT_FALSE(rm.is_bound1());
   for (int i = 0; i < RegMask::CHUNK_SIZE - 1; i++) {
     rm.Insert(i);
-    ASSERT_TRUE(rm.is_bound1());
+    ASSERT_TRUE(rm.is_bound1())       << "Index " << i;
+    ASSERT_TRUE(rm.is_bound(Op_RegI)) << "Index " << i;
     contains_expected_num_of_registers(rm, 1);
     rm.Remove(i);
   }
   // AllStack bit does not count as a bound register
   rm.set_AllStack();
   ASSERT_FALSE(rm.is_bound1());
 }
+
+TEST_VM(RegMask, is_bound_pair) {
+  RegMask rm;
+  ASSERT_TRUE(rm.is_bound_pair());
+  for (int i = 0; i < RegMask::CHUNK_SIZE - 2; i++) {
+    rm.Insert(i);
+    rm.Insert(i + 1);
+    ASSERT_TRUE(rm.is_bound_pair())   << "Index " << i;
+    ASSERT_TRUE(rm.is_bound_set(2))   << "Index " << i;
+    ASSERT_TRUE(rm.is_bound(Op_RegI)) << "Index " << i;
+    contains_expected_num_of_registers(rm, 2);
+    rm.Clear();
+  }
+  // A pair with the AllStack bit does not count as a bound pair
+  rm.Clear();
+  rm.Insert(RegMask::CHUNK_SIZE - 2);
+  rm.Insert(RegMask::CHUNK_SIZE - 1);
+  ASSERT_FALSE(rm.is_bound_pair());
+}
+
+TEST_VM(RegMask, is_bound_set) {
+  RegMask rm;
+  for (int size = 1; size <= 16; size++) {
+    ASSERT_TRUE(rm.is_bound_set(size));
+    for (int i = 0; i < RegMask::CHUNK_SIZE - size; i++) {
+      for (int j = i; j < i + size; j++) {
+        rm.Insert(j);
+      }
+      ASSERT_TRUE(rm.is_bound_set(size))   << "Size " << size << " Index " << i;
+      contains_expected_num_of_registers(rm, size);
+      rm.Clear();
+    }
+    // A set with the AllStack bit does not count as a bound set
+    for (int j = RegMask::CHUNK_SIZE - size; j < RegMask::CHUNK_SIZE; j++) {
+        rm.Insert(j);
+    }
+    ASSERT_FALSE(rm.is_bound_set(size));
+    rm.Clear();
+  }
+}