From 3135a96dc0a615a6fbedc9dd0657ec1c75d8723e Mon Sep 17 00:00:00 2001
From: Christian Hagedorn <christian.hagedorn@oracle.com>
Date: Mon, 29 Jul 2019 09:40:02 +0200
Subject: [PATCH] 8156207: Resource allocated BitMaps are often cleared
 unnecessarily

Removed unnecessary clearing of BitMap.

Reviewed-by: kbarrett, kvn, thartmann
---
 src/hotspot/share/compiler/methodLiveness.cpp | 4 ++--
 src/hotspot/share/utilities/bitMap.cpp        | 4 ++--
 src/hotspot/share/utilities/bitMap.hpp        | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/hotspot/share/compiler/methodLiveness.cpp b/src/hotspot/share/compiler/methodLiveness.cpp
index 7cff216b0c5..67bec91eb72 100644
--- a/src/hotspot/share/compiler/methodLiveness.cpp
+++ b/src/hotspot/share/compiler/methodLiveness.cpp
@@ -830,8 +830,8 @@ MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* metho
 
 #ifdef ASSERT
   ResourceMark rm;
-  ResourceBitMap g(_gen.size()); g.set_from(_gen);
-  ResourceBitMap k(_kill.size()); k.set_from(_kill);
+  ResourceBitMap g(_gen.size(), false); g.set_from(_gen);
+  ResourceBitMap k(_kill.size(), false); k.set_from(_kill);
 #endif
   if (_last_bci != bci || trueInDebug) {
     ciBytecodeStream bytes(method);
diff --git a/src/hotspot/share/utilities/bitMap.cpp b/src/hotspot/share/utilities/bitMap.cpp
index f88f11fb7ec..3afa22ee1e2 100644
--- a/src/hotspot/share/utilities/bitMap.cpp
+++ b/src/hotspot/share/utilities/bitMap.cpp
@@ -133,8 +133,8 @@ void BitMap::reinitialize(const Allocator& allocator, idx_t new_size_in_bits, bo
   initialize(allocator, new_size_in_bits, clear);
 }
 
-ResourceBitMap::ResourceBitMap(idx_t size_in_bits)
-    : BitMap(allocate(ResourceBitMapAllocator(), size_in_bits), size_in_bits) {
+ResourceBitMap::ResourceBitMap(idx_t size_in_bits, bool clear)
+    : BitMap(allocate(ResourceBitMapAllocator(), size_in_bits, clear), size_in_bits) {
 }
 
 void ResourceBitMap::resize(idx_t new_size_in_bits) {
diff --git a/src/hotspot/share/utilities/bitMap.hpp b/src/hotspot/share/utilities/bitMap.hpp
index e8e361dfe33..84046942633 100644
--- a/src/hotspot/share/utilities/bitMap.hpp
+++ b/src/hotspot/share/utilities/bitMap.hpp
@@ -329,8 +329,8 @@ class ResourceBitMap : public BitMap {
 
  public:
   ResourceBitMap() : BitMap(NULL, 0) {}
-  // Clears the bitmap memory.
-  ResourceBitMap(idx_t size_in_bits);
+  // Conditionally clears the bitmap memory.
+  ResourceBitMap(idx_t size_in_bits, bool clear = true);
 
   // Resize the backing bitmap memory.
   //