vsk created this revision.
vsk added reviewers: teemperor, lhames.
Profiling data show that Allocation::operator= is hot, see:
https://teemperor.de/lldb-bench/data/arithmetic.svg
Reorder a few fields within Allocation to avoid implicit structure
padding and shrink the structure. This should make copies cheaper and
reduce lldb's RSS.
There should be more low-hanging fruit here for performance
optimization: we don't need std::map, we can make Allocation move-only,
etc.
https://reviews.llvm.org/D50271
Files:
lldb/include/lldb/Expression/IRMemoryMap.h
lldb/source/Expression/IRMemoryMap.cpp
Index: lldb/source/Expression/IRMemoryMap.cpp
===================================================================
--- lldb/source/Expression/IRMemoryMap.cpp
+++ lldb/source/Expression/IRMemoryMap.cpp
@@ -272,8 +272,8 @@
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!");
Index: lldb/include/lldb/Expression/IRMemoryMap.h
===================================================================
--- lldb/include/lldb/Expression/IRMemoryMap.h
+++ lldb/include/lldb/Expression/IRMemoryMap.h
@@ -39,7 +39,7 @@
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 +91,36 @@
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) {}
+ m_process_start(LLDB_INVALID_ADDRESS), m_size(0), m_data(),
+ m_policy(eAllocationPolicyInvalid), m_leak(false), m_permissions(0),
+ m_alignment(0) {}
};
+ 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;
Index: lldb/source/Expression/IRMemoryMap.cpp
===================================================================
--- lldb/source/Expression/IRMemoryMap.cpp
+++ lldb/source/Expression/IRMemoryMap.cpp
@@ -272,8 +272,8 @@
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!");
Index: lldb/include/lldb/Expression/IRMemoryMap.h
===================================================================
--- lldb/include/lldb/Expression/IRMemoryMap.h
+++ lldb/include/lldb/Expression/IRMemoryMap.h
@@ -39,7 +39,7 @@
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 +91,36 @@
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) {}
+ m_process_start(LLDB_INVALID_ADDRESS), m_size(0), m_data(),
+ m_policy(eAllocationPolicyInvalid), m_leak(false), m_permissions(0),
+ m_alignment(0) {}
};
+ 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;
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