OpenJDK / jigsaw / jake / hotspot
changeset 6946:f62b69773aaf
8054927: Missing MemNode::acquire ordering in some volatile Load nodes
Summary: Fixed memory ordering parameter and added missing barriers for volatile loads.
Reviewed-by: roland, iveresov
| author | kvn |
|---|---|
| date | Wed, 13 Aug 2014 13:05:04 -0700 |
| parents | 3d0f5e4b3eec |
| children | 4395c63e455b |
| files | src/share/vm/opto/library_call.cpp |
| diffstat | 1 files changed, 14 insertions(+), 2 deletions(-) [+] |
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--- a/src/share/vm/opto/library_call.cpp Wed Aug 13 09:53:18 2014 +0000 +++ b/src/share/vm/opto/library_call.cpp Wed Aug 13 13:05:04 2014 -0700 @@ -2595,7 +2595,8 @@ if (need_mem_bar) insert_mem_bar(Op_MemBarCPUOrder); if (!is_store) { - Node* p = make_load(control(), adr, value_type, type, adr_type, MemNode::unordered, is_volatile); + MemNode::MemOrd mo = is_volatile ? MemNode::acquire : MemNode::unordered; + Node* p = make_load(control(), adr, value_type, type, adr_type, mo, is_volatile); // load value switch (type) { case T_BOOLEAN: @@ -5096,8 +5097,19 @@ type = Type::get_const_basic_type(bt); } + if (support_IRIW_for_not_multiple_copy_atomic_cpu && is_vol) { + insert_mem_bar(Op_MemBarVolatile); // StoreLoad barrier + } // Build the load. - Node* loadedField = make_load(NULL, adr, type, bt, adr_type, MemNode::unordered, is_vol); + MemNode::MemOrd mo = is_vol ? MemNode::acquire : MemNode::unordered; + Node* loadedField = make_load(NULL, adr, type, bt, adr_type, mo, is_vol); + // If reference is volatile, prevent following memory ops from + // floating up past the volatile read. Also prevents commoning + // another volatile read. + if (is_vol) { + // Memory barrier includes bogus read of value to force load BEFORE membar + insert_mem_bar(Op_MemBarAcquire, loadedField); + } return loadedField; }