8257912: Convert enum iteration to use range-based for loops

Reviewed-by: kbarrett, tschatzl, gziemski

Author: iklam

src/hotspot/share/ci/ciObjectFactory.cpp

@@ -122,17 +122,15 @@ void ciObjectFactory::init_shared_objects() {
 
   {
     // Create the shared symbols, but not in _shared_ci_metadata.
-    for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-      vmSymbolID index = *it;
+    for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
       Symbol* vmsym = vmSymbols::symbol_at(index);
       assert(vmSymbols::find_sid(vmsym) == index, "1-1 mapping");
       ciSymbol* sym = new (_arena) ciSymbol(vmsym, index);
       init_ident_of(sym);
       _shared_ci_symbols[vmSymbols::as_int(index)] = sym;
     }
 #ifdef ASSERT
-    for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-      vmSymbolID index = *it;
+    for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
       Symbol* vmsym = vmSymbols::symbol_at(index);
       ciSymbol* sym = vm_symbol_at(index);
       assert(sym->get_symbol() == vmsym, "oop must match");

src/hotspot/share/classfile/classFileParser.cpp

@@ -5302,8 +5302,7 @@ static void check_methods_for_intrinsics(const InstanceKlass* ik,
       // The check is potentially expensive, therefore it is available
       // only in debug builds.
 
-      for (vmIntrinsicsIterator it = vmIntrinsicsRange.begin(); it != vmIntrinsicsRange.end(); ++it) {
-        vmIntrinsicID id = *it;
+      for (vmIntrinsicID id : EnumRange<vmIntrinsicID>{}) {
         if (vmIntrinsics::_compiledLambdaForm == id) {
           // The _compiledLamdbdaForm intrinsic is a special marker for bytecode
           // generated for the JVM from a LambdaForm and therefore no method

src/hotspot/share/classfile/vmIntrinsics.cpp

@@ -574,8 +574,7 @@ void vmIntrinsics::init_vm_intrinsic_name_table() {
   const char** nt = &vm_intrinsic_name_table[0];
   char* string = (char*) &vm_intrinsic_name_bodies[0];
 
-  for (vmIntrinsicsIterator it = vmIntrinsicsRange.begin(); it != vmIntrinsicsRange.end(); ++it) {
-    vmIntrinsicID index = *it;
+  for (vmIntrinsicID index : EnumRange<vmIntrinsicID>{}) {
     nt[as_int(index)] = string;
     string += strlen(string); // skip string body
     string += 1;              // skip trailing null
@@ -602,8 +601,7 @@ vmIntrinsics::ID vmIntrinsics::find_id(const char* name) {
     init_vm_intrinsic_name_table();
   }
 
-  for (vmIntrinsicsIterator it = vmIntrinsicsRange.begin(); it != vmIntrinsicsRange.end(); ++it) {
-    vmIntrinsicID index = *it;
+  for (vmIntrinsicID index : EnumRange<vmIntrinsicID>{}) {
     if (0 == strcmp(name, nt[as_int(index)])) {
       return index;
     }

src/hotspot/share/classfile/vmIntrinsics.hpp

@@ -1044,8 +1044,6 @@ enum class vmIntrinsicID : int {
 };
 
 ENUMERATOR_RANGE(vmIntrinsicID, vmIntrinsicID::FIRST_ID, vmIntrinsicID::LAST_ID)
-constexpr EnumRange<vmIntrinsicID> vmIntrinsicsRange; // the default range of all valid vmIntrinsicIDs
-using vmIntrinsicsIterator = EnumIterator<vmIntrinsicID>; // convenience
 
 class vmIntrinsics : AllStatic {
   friend class vmSymbols;

src/hotspot/share/classfile/vmSymbols.cpp

@@ -83,8 +83,7 @@ void vmSymbols::initialize(TRAPS) {
 
   if (!UseSharedSpaces) {
     const char* string = &vm_symbol_bodies[0];
-    for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-      vmSymbolID index = *it;
+    for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
       Symbol* sym = SymbolTable::new_permanent_symbol(string);
       Symbol::_vm_symbols[as_int(index)] = sym;
       string += strlen(string); // skip string body
@@ -113,12 +112,11 @@ void vmSymbols::initialize(TRAPS) {
 
 #ifdef ASSERT
   // Check for duplicates:
-  for (vmSymbolsIterator it1 = vmSymbolsRange.begin(); it1 != vmSymbolsRange.end(); ++it1) {
-    vmSymbolID i1 = *it1;
+
+  for (vmSymbolID i1 : EnumRange<vmSymbolID>{}) {
     Symbol* sym = symbol_at(i1);
-    for (vmSymbolsIterator it2 = vmSymbolsRange.begin(); it2 != it1; ++it2) {
-      vmSymbolID i2 = *it2;
-      if (symbol_at(i2) == sym) {
+    for (vmSymbolID i2 : EnumRange<vmSymbolID>{vmSymbolID::FIRST_SID, i1}) {
+      if (i2 != i1 && symbol_at(i2) == sym) {
         tty->print("*** Duplicate VM symbol SIDs %s(%d) and %s(%d): \"",
                    vm_symbol_enum_name(i2), as_int(i2),
                    vm_symbol_enum_name(i1), as_int(i1));
@@ -131,8 +129,7 @@ void vmSymbols::initialize(TRAPS) {
 
   // Create an index for find_id:
   {
-    for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-      vmSymbolID index = *it;
+    for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
       vm_symbol_index[as_int(index)] = index;
     }
     int num_sids = SID_LIMIT-FIRST_SID;
@@ -153,8 +150,7 @@ void vmSymbols::initialize(TRAPS) {
     assert(symbol_at(sid) == jlo, "");
 
     // Make sure find_sid produces the right answer in each case.
-    for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-      vmSymbolID index = *it;
+    for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
       Symbol* sym = symbol_at(index);
       sid = find_sid(sym);
       assert(sid == index, "symbol index works");
@@ -178,8 +174,7 @@ const char* vmSymbols::name_for(vmSymbolID sid) {
   if (sid == vmSymbolID::NO_SID)
     return "NO_SID";
   const char* string = &vm_symbol_bodies[0];
-  for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-    vmSymbolID index = *it;
+  for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
     if (index == sid)
       return string;
     string += strlen(string); // skip string body
@@ -192,8 +187,7 @@ const char* vmSymbols::name_for(vmSymbolID sid) {
 
 
 void vmSymbols::symbols_do(SymbolClosure* f) {
-  for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-    vmSymbolID index = *it;
+  for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
     f->do_symbol(&Symbol::_vm_symbols[as_int(index)]);
   }
   for (int i = 0; i < T_VOID+1; i++) {
@@ -202,8 +196,7 @@ void vmSymbols::symbols_do(SymbolClosure* f) {
 }
 
 void vmSymbols::metaspace_pointers_do(MetaspaceClosure *closure) {
-  for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-    vmSymbolID index = *it;
+  for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
     closure->push(&Symbol::_vm_symbols[as_int(index)]);
   }
   for (int i = 0; i < T_VOID+1; i++) {
@@ -281,8 +274,7 @@ vmSymbolID vmSymbols::find_sid(const Symbol* symbol) {
     // Make sure this is the right answer, using linear search.
     // (We have already proven that there are no duplicates in the list.)
     vmSymbolID sid2 = vmSymbolID::NO_SID;
-    for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
-      vmSymbolID index = *it;
+    for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
       Symbol* sym2 = symbol_at(index);
       if (sym2 == symbol) {
         sid2 = index;

src/hotspot/share/classfile/vmSymbols.hpp

@@ -722,8 +722,6 @@ enum class vmSymbolID : int {
 };
 
 ENUMERATOR_RANGE(vmSymbolID, vmSymbolID::FIRST_SID, vmSymbolID::LAST_SID)
-constexpr EnumRange<vmSymbolID> vmSymbolsRange; // the default range of all valid vmSymbolIDs
-using vmSymbolsIterator = EnumIterator<vmSymbolID>; // convenience
 
 class vmSymbols: AllStatic {
   friend class vmIntrinsics;

src/hotspot/share/jfr/recorder/checkpoint/types/jfrType.cpp

@@ -138,11 +138,10 @@ static const char* flag_value_origin_to_string(JVMFlagOrigin origin) {
 }
 
 void FlagValueOriginConstant::serialize(JfrCheckpointWriter& writer) {
-  constexpr EnumRange<JVMFlagOrigin> range;
+  constexpr EnumRange<JVMFlagOrigin> range{};
   writer.write_count(static_cast<u4>(range.size()));
 
-  for (EnumIterator<JVMFlagOrigin> it = range.begin(); it != range.end(); ++it) {
-    JVMFlagOrigin origin = *it;
+  for (JVMFlagOrigin origin : range) {
     writer.write_key(static_cast<u4>(origin));
     writer.write(flag_value_origin_to_string(origin));
   }

src/hotspot/share/opto/compile.cpp

@@ -234,8 +234,7 @@ void Compile::print_intrinsic_statistics() {
   if (total == 0)  total = 1;  // avoid div0 in case of no successes
   #define PRINT_STAT_LINE(name, c, f) \
     tty->print_cr("  %4d (%4.1f%%) %s (%s)", (int)(c), ((c) * 100.0) / total, name, f);
-  for (vmIntrinsicsIterator it = vmIntrinsicsRange.begin(); it != vmIntrinsicsRange.end(); ++it) {
-    vmIntrinsicID id = *it;
+  for (vmIntrinsicID id : EnumRange<vmIntrinsicID>{}) {
     int   flags = _intrinsic_hist_flags[as_int(id)];
     juint count = _intrinsic_hist_count[as_int(id)];
     if ((flags | count) != 0) {

src/hotspot/share/utilities/enumIterator.hpp

@@ -57,21 +57,19 @@
 // EnumRange -- defines the range of *one specific* iteration loop.
 // EnumIterator -- the current point in the iteration loop.
 
-// Example (see vmSymbols.hpp/cpp)
+// Example:
 //
-// ENUMERATOR_RANGE(vmSymbolID, vmSymbolID::FIRST_SID, vmSymbolID::LAST_SID)
-// constexpr EnumRange<vmSymbolID> vmSymbolsRange;
-// using vmSymbolsIterator = EnumIterator<vmSymbolID>;
+// /* With range-base for (recommended) */
+// for (vmSymbolID index : EnumRange<vmSymbolID>{}) {
+//    ....
+// }
 //
-// /* Without range-based for, allowed */
+// /* Without range-based for */
+// constexpr EnumRange<vmSymbolID> vmSymbolsRange{};
+// using vmSymbolsIterator = EnumIterator<vmSymbolID>;
 // for (vmSymbolsIterator it = vmSymbolsRange.begin(); it != vmSymbolsRange.end(); ++it) {
 //  vmSymbolID index = *it; ....
 // }
-//
-// /* With range-base for, not allowed by HotSpot coding style yet */
-// for (vmSymbolID index : vmSymbolsRange) {
-//    ....
-// }
 
 // EnumeratorRange is a traits type supporting iteration over the enumerators of T.
 // Specializations must provide static const data members named "_start" and "_end".

test/hotspot/gtest/utilities/test_enumIterator.cpp

@@ -110,3 +110,71 @@ TEST(TestEnumIterator, implicit_iterator) {
   }
   EXPECT_EQ(it, range.end());
 }
+
+TEST(TestEnumIterator, explict_range_based_for_loop_full) {
+  int i = explicit_start;
+  for (ExplicitTest value : EnumRange<ExplicitTest>{}) {
+    EXPECT_EQ(size_t(i - explicit_start), EnumRange<ExplicitTest>{}.index(value));
+    EXPECT_TRUE(value == ExplicitTest::value1 ||
+                value == ExplicitTest::value2 ||
+                value == ExplicitTest::value3);
+    ++i;
+  }
+}
+
+TEST(TestEnumIterator, explict_range_based_for_loop_start) {
+  constexpr EnumRange<ExplicitTest> range{ExplicitTest::value2};
+  int start = explicit_start + 2;
+  int i = start;
+  for (ExplicitTest value : range) {
+    EXPECT_EQ(size_t(i - start), range.index(value));
+    EXPECT_TRUE(value == ExplicitTest::value2 || value == ExplicitTest::value3);
+    EXPECT_TRUE(value != ExplicitTest::value1);
+    ++i;
+  }
+}
+
+TEST(TestEnumIterator, explict_range_based_for_loop_start_end) {
+  constexpr EnumRange<ExplicitTest> range{ExplicitTest::value1, ExplicitTest::value2};
+  int start = explicit_start + 1;
+  int i = start;
+  for (ExplicitTest value : range) {
+    EXPECT_EQ(size_t(i - start), range.index(value));
+    EXPECT_TRUE(value == ExplicitTest::value1 || value == ExplicitTest::value2);
+    EXPECT_TRUE(value != ExplicitTest::value3);
+    ++i;
+  }
+}
+
+TEST(TestEnumIterator, implicit_range_based_for_loop) {
+  int i = implicit_start;
+  for (ImplicitTest value : EnumRange<ImplicitTest>{}) {
+    EXPECT_EQ(size_t(i - implicit_start), EnumRange<ImplicitTest>{}.index(value));
+    ++i;
+  }
+}
+
+TEST(TestEnumIterator, implicit_range_based_for_loop_start) {
+  int start = implicit_start + 1;
+  EnumRange<ImplicitTest> range{static_cast<ImplicitTest>(start)};
+  int i = start;
+  for (ImplicitTest value : range) {
+    EXPECT_EQ(size_t(i - start), range.index(value));
+    int iv = static_cast<int>(value);
+    EXPECT_TRUE(start <= iv && iv <= implicit_end);
+    ++i;
+  }
+}
+
+TEST(TestEnumIterator, implicit_range_based_for_loop_start_end) {
+  int start = implicit_start + 1;
+  int end = implicit_end - 1;
+  EnumRange<ImplicitTest> range{static_cast<ImplicitTest>(start), static_cast<ImplicitTest>(end)};
+  int i = start;
+  for (ImplicitTest value : range) {
+    EXPECT_EQ(size_t(i - start), range.index(value));
+    int iv = static_cast<int>(value);
+    EXPECT_TRUE(start <= iv && iv <= end);
+    ++i;
+  }
+}