8314932: G1: Fix -Wconversion warnings for simple cases inside g1 folder

Reviewed-by: tschatzl, iwalulya

src/hotspot/share/gc/g1/g1Analytics.cpp

@@ -94,7 +94,7 @@ G1Analytics::G1Analytics(const G1Predictions* predictor) :
   _recent_prev_end_times_for_all_gcs_sec.add(os::elapsedTime());
   _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 
-  int index = MIN2(ParallelGCThreads - 1, 7u);
+  uint index = MIN2(ParallelGCThreads - 1, 7u);
 
   // Start with inverse of maximum STW cost.
   _concurrent_refine_rate_ms_seq.add(1/cost_per_logged_card_ms_defaults[0]);

src/hotspot/share/gc/g1/g1BlockOffsetTable.inline.hpp

@@ -46,7 +46,7 @@ inline HeapWord* G1BlockOffsetTablePart::block_start_reaching_into_card(const vo
 
   size_t index = _bot->index_for(addr);
 
-  uint offset = _bot->offset_array(index);
+  u_char offset = _bot->offset_array(index);
   while (offset >= BOTConstants::card_size_in_words()) {
     // The excess of the offset from N_words indicates a power of Base
     // to go back by.

src/hotspot/share/gc/g1/g1CardTable.cpp

@@ -32,7 +32,7 @@ void G1CardTable::g1_mark_as_young(const MemRegion& mr) {
   CardValue *const first = byte_for(mr.start());
   CardValue *const last = byte_after(mr.last());
 
-  memset_with_concurrent_readers(first, g1_young_gen, last - first);
+  memset_with_concurrent_readers(first, g1_young_gen, pointer_delta(last, first, sizeof(CardValue)));
 }
 
 #ifndef PRODUCT

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -390,8 +390,8 @@ G1ConcurrentMark::G1ConcurrentMark(G1CollectedHeap* g1h,
   // _num_active_tasks set in set_non_marking_state()
   // _tasks set inside the constructor
 
-  _task_queues(new G1CMTaskQueueSet((int) _max_num_tasks)),
-  _terminator((int) _max_num_tasks, _task_queues),
+  _task_queues(new G1CMTaskQueueSet(_max_num_tasks)),
+  _terminator(_max_num_tasks, _task_queues),
 
   _first_overflow_barrier_sync(),
   _second_overflow_barrier_sync(),
@@ -540,8 +540,8 @@ void G1ConcurrentMark::set_concurrency(uint active_tasks) {
   // Need to update the three data structures below according to the
   // number of active threads for this phase.
   _terminator.reset_for_reuse(active_tasks);
-  _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
-  _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
+  _first_overflow_barrier_sync.set_n_workers(active_tasks);
+  _second_overflow_barrier_sync.set_n_workers(active_tasks);
 }
 
 void G1ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {

src/hotspot/share/gc/g1/g1ConcurrentMark.hpp

@@ -511,7 +511,7 @@ public:
   // running.
   void abort_marking_threads();
 
-  void update_accum_task_vtime(int i, double vtime) {
+  void update_accum_task_vtime(uint i, double vtime) {
     _accum_task_vtime[i] += vtime;
   }
 

src/hotspot/share/gc/g1/g1ConcurrentMarkObjArrayProcessor.cpp

@@ -74,7 +74,7 @@ size_t G1CMObjArrayProcessor::process_slice(HeapWord* slice) {
 
   objArrayOop objArray = objArrayOop(cast_to_oop(start_address));
 
-  size_t already_scanned = slice - start_address;
+  size_t already_scanned = pointer_delta(slice, start_address);
   size_t remaining = objArray->size() - already_scanned;
 
   return process_array_slice(objArray, slice, remaining);

src/hotspot/share/gc/g1/g1EdenRegions.hpp

@@ -32,7 +32,7 @@
 
 class G1EdenRegions {
 private:
-  int    _length;
+  uint    _length;
   // Sum of used bytes from all retired eden regions.
   // I.e. updated when mutator regions are retired.
   volatile size_t _used_bytes;

src/hotspot/share/gc/g1/g1FreeIdSet.cpp

@@ -26,6 +26,7 @@
 #include "gc/g1/g1FreeIdSet.hpp"
 #include "memory/allocation.inline.hpp"
 #include "runtime/atomic.hpp"
+#include "utilities/checkedCast.hpp"
 #include "utilities/debug.hpp"
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/macros.hpp"
@@ -59,7 +60,7 @@ G1FreeIdSet::~G1FreeIdSet() {
 }
 
 uint G1FreeIdSet::head_index(uintx head) const {
-  return head & _head_index_mask;
+  return checked_cast<uint>(head & _head_index_mask);
 }
 
 uintx G1FreeIdSet::make_head(uint index, uintx old_head) const {

src/hotspot/share/gc/g1/g1PageBasedVirtualSpace.cpp

@@ -100,10 +100,6 @@ size_t G1PageBasedVirtualSpace::uncommitted_size()  const {
   return reserved_size() - committed_size();
 }
 
-size_t G1PageBasedVirtualSpace::addr_to_page_index(char* addr) const {
-  return (addr - _low_boundary) / _page_size;
-}
-
 bool G1PageBasedVirtualSpace::is_area_committed(size_t start_page, size_t size_in_pages) const {
   size_t end_page = start_page + size_in_pages;
   return _committed.find_first_clear_bit(start_page, end_page) >= end_page;

src/hotspot/share/gc/g1/g1PageBasedVirtualSpace.hpp

@@ -84,9 +84,6 @@ class G1PageBasedVirtualSpace {
   // Uncommit the given memory range.
   void uncommit_internal(size_t start_page, size_t end_page);
 
-  // Returns the index of the page which contains the given address.
-  size_t  addr_to_page_index(char* addr) const;
-
   // Is the given page index the last page?
   bool is_last_page(size_t index) const { return index == (_committed.size() - 1); }
   // Is the given page index the first after last page?

src/hotspot/share/gc/g1/g1RemSet.cpp

@@ -545,7 +545,7 @@ class G1ScanHRForRegionClosure : public HeapRegionClosure {
 
   void do_claimed_block(uint const region_idx, CardValue* const dirty_l, CardValue* const dirty_r) {
     _ct->change_dirty_cards_to(dirty_l, dirty_r, _scanned_card_value);
-    size_t num_cards = dirty_r - dirty_l;
+    size_t num_cards = pointer_delta(dirty_r, dirty_l, sizeof(CardValue));
     _blocks_scanned++;
 
     HeapWord* const card_start = _ct->addr_for(dirty_l);

src/hotspot/share/gc/g1/g1RemSetTrackingPolicy.cpp

@@ -103,7 +103,7 @@ bool G1RemSetTrackingPolicy::update_before_rebuild(HeapRegion* r, size_t live_by
 
   assert(!r->rem_set()->is_updating(), "Remembered set of region %u is updating before rebuild", r->hrm_index());
 
-  size_t live_bytes_above_tams = (r->top() - r->top_at_mark_start()) * HeapWordSize;
+  size_t live_bytes_above_tams = pointer_delta(r->top(), r->top_at_mark_start()) * HeapWordSize;
   size_t total_live_bytes = live_bytes_below_tams + live_bytes_above_tams;
 
   bool selected_for_rebuild = false;