Author: vedantk Date: Wed Aug 8 14:26:49 2018 New Revision: 339290 URL: http://llvm.org/viewvc/llvm-project?rev=339290&view=rev Log: [IRMemoryMap] Shrink Allocation and make it move-only (NFC)
Profiling data show that Allocation::operator= is hot (see the data attached to the Phab review). Reorder a few fields within Allocation to avoid implicit structure padding and shrink the structure. This should make copies a bit cheaper. Also, given that an Allocation contains a std::vector (by way of DataBufferHeap), it's preferable to make it move-only instead of permitting expensive copies. As an added benefit this allows us to have a single Allocation constructor instead of two. Differential Revision: https://reviews.llvm.org/D50271 Modified: lldb/trunk/include/lldb/Expression/IRMemoryMap.h lldb/trunk/source/Expression/IRMemoryMap.cpp Modified: lldb/trunk/include/lldb/Expression/IRMemoryMap.h URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Expression/IRMemoryMap.h?rev=339290&r1=339289&r2=339290&view=diff ============================================================================== --- lldb/trunk/include/lldb/Expression/IRMemoryMap.h (original) +++ lldb/trunk/include/lldb/Expression/IRMemoryMap.h Wed Aug 8 14:26:49 2018 @@ -39,7 +39,7 @@ public: IRMemoryMap(lldb::TargetSP target_sp); ~IRMemoryMap(); - enum AllocationPolicy { + enum AllocationPolicy : uint8_t { eAllocationPolicyInvalid = 0, ///< It is an error for an allocation to have this policy. eAllocationPolicyHostOnly, ///< This allocation was created in the host and @@ -91,32 +91,32 @@ protected: private: struct Allocation { lldb::addr_t - m_process_alloc; ///< The (unaligned) base for the remote allocation + m_process_alloc; ///< The (unaligned) base for the remote allocation. lldb::addr_t - m_process_start; ///< The base address of the allocation in the process - size_t m_size; ///< The size of the requested allocation - uint32_t m_permissions; ///< The access permissions on the memory in the - ///process. In the host, the memory is always - ///read/write. - uint8_t m_alignment; ///< The alignment of the requested allocation + m_process_start; ///< The base address of the allocation in the process. + size_t m_size; ///< The size of the requested allocation. DataBufferHeap m_data; - ///< Flags + /// Flags. Keep these grouped together to avoid structure padding. AllocationPolicy m_policy; bool m_leak; + uint8_t m_permissions; ///< The access permissions on the memory in the + /// process. In the host, the memory is always + /// read/write. + uint8_t m_alignment; ///< The alignment of the requested allocation. public: Allocation(lldb::addr_t process_alloc, lldb::addr_t process_start, size_t size, uint32_t permissions, uint8_t alignment, AllocationPolicy m_policy); - Allocation() - : m_process_alloc(LLDB_INVALID_ADDRESS), - m_process_start(LLDB_INVALID_ADDRESS), m_size(0), m_permissions(0), - m_alignment(0), m_data(), m_policy(eAllocationPolicyInvalid), - m_leak(false) {} + DISALLOW_COPY_AND_ASSIGN(Allocation); }; + static_assert(sizeof(Allocation) <= + (4 * sizeof(lldb::addr_t)) + sizeof(DataBufferHeap), + "IRMemoryMap::Allocation is larger than expected"); + lldb::ProcessWP m_process_wp; lldb::TargetWP m_target_wp; typedef std::map<lldb::addr_t, Allocation> AllocationMap; Modified: lldb/trunk/source/Expression/IRMemoryMap.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Expression/IRMemoryMap.cpp?rev=339290&r1=339289&r2=339290&view=diff ============================================================================== --- lldb/trunk/source/Expression/IRMemoryMap.cpp (original) +++ lldb/trunk/source/Expression/IRMemoryMap.cpp Wed Aug 8 14:26:49 2018 @@ -272,8 +272,8 @@ IRMemoryMap::Allocation::Allocation(lldb uint32_t permissions, uint8_t alignment, AllocationPolicy policy) : m_process_alloc(process_alloc), m_process_start(process_start), - m_size(size), m_permissions(permissions), m_alignment(alignment), - m_policy(policy), m_leak(false) { + m_size(size), m_policy(policy), m_leak(false), m_permissions(permissions), + m_alignment(alignment) { switch (policy) { default: assert(0 && "We cannot reach this!"); @@ -389,9 +389,10 @@ lldb::addr_t IRMemoryMap::Malloc(size_t lldb::addr_t mask = alignment - 1; aligned_address = (allocation_address + mask) & (~mask); - m_allocations[aligned_address] = - Allocation(allocation_address, aligned_address, allocation_size, - permissions, alignment, policy); + m_allocations.emplace( + std::piecewise_construct, std::forward_as_tuple(aligned_address), + std::forward_as_tuple(allocation_address, aligned_address, + allocation_size, permissions, alignment, policy)); if (zero_memory) { Status write_error; _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
