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noahfalknoahfalk
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Add ee_alloc_context
This change is some preparatory refactoring for the randomized allocation sampling feature. We need to add more state onto allocation context but we don't want to do a breaking change of the GC interface. The new state only needs to be visible to the EE but we want it physically near the existing alloc context state for good cache locality. To accomplish this we created a new ee_alloc_context struct which contains an instance of gc_alloc_context within it. The new ee_alloc_context.combined_limit field should be used by fast allocation helpers to determine when to go down the slow path. Most of the time combined_limit has the same value as alloc_limit, but periodically we need to emit an allocation sampling event on an object that is somewhere in the middle of an AC. Using combined_limit rather than alloc_limit as the slow path trigger allows us to keep all the sampling event logic in the slow path.
1 parent 42b2b19 commit d8e7fce

23 files changed

+190
-81
lines changed

‎src/coreclr/debug/daccess/dacdbiimpl.cpp‎

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -6551,10 +6551,11 @@ HRESULT DacHeapWalker::Init(CORDB_ADDRESS start, CORDB_ADDRESS end)
65516551
j++;
65526552
}
65536553
}
6554-
if ((&g_global_alloc_context)->alloc_ptr != nullptr)
6554+
gc_alloc_context globalCtx = ((ee_alloc_context)g_global_alloc_context).gc_allocation_context;
6555+
if (globalCtx.alloc_ptr != nullptr)
65556556
{
6556-
mAllocInfo[j].Ptr = (CORDB_ADDRESS)(&g_global_alloc_context)->alloc_ptr;
6557-
mAllocInfo[j].Limit = (CORDB_ADDRESS)(&g_global_alloc_context)->alloc_limit;
6557+
mAllocInfo[j].Ptr = (CORDB_ADDRESS)globalCtx.alloc_ptr;
6558+
mAllocInfo[j].Limit = (CORDB_ADDRESS)globalCtx.alloc_limit;
65586559
}
65596560

65606561
mThreadCount = j;

‎src/coreclr/debug/daccess/request.cpp‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -5493,8 +5493,9 @@ HRESULT ClrDataAccess::GetGlobalAllocationContext(
54935493
}
54945494

54955495
SOSDacEnter();
5496-
*allocPtr = (CLRDATA_ADDRESS)((&g_global_alloc_context)->alloc_ptr);
5497-
*allocLimit = (CLRDATA_ADDRESS)((&g_global_alloc_context)->alloc_limit);
5496+
gc_alloc_context global_alloc_context = ((ee_alloc_context)g_global_alloc_context).gc_allocation_context;
5497+
*allocPtr = (CLRDATA_ADDRESS)global_alloc_context.alloc_ptr;
5498+
*allocLimit = (CLRDATA_ADDRESS)global_alloc_context.alloc_limit;
54985499
SOSDacLeave();
54995500
return hr;
55005501
}

‎src/coreclr/debug/runtimeinfo/datadescriptor.h‎

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -132,9 +132,14 @@ CDAC_TYPE_END(ThreadStore)
132132

133133
CDAC_TYPE_BEGIN(RuntimeThreadLocals)
134134
CDAC_TYPE_INDETERMINATE(RuntimeThreadLocals)
135-
CDAC_TYPE_FIELD(RuntimeThreadLocals, AllocContext, AllocContext, offsetof(RuntimeThreadLocals, alloc_context))
135+
CDAC_TYPE_FIELD(RuntimeThreadLocals, /*EEAllocContext*/, AllocContext, offsetof(RuntimeThreadLocals, alloc_context))
136136
CDAC_TYPE_END(RuntimeThreadLocals)
137137

138+
CDAC_TYPE_BEGIN(EEAllocContext)
139+
CDAC_TYPE_INDETERMINATE(EEAllocContext)
140+
CDAC_TYPE_FIELD(EEAllocContext, /*GCAllocContext*/, GCAllocationContext, offsetof(ee_alloc_context, gc_allocation_context))
141+
CDAC_TYPE_END(EEAllocContext)
142+
138143
CDAC_TYPE_BEGIN(GCAllocContext)
139144
CDAC_TYPE_INDETERMINATE(GCAllocContext)
140145
CDAC_TYPE_FIELD(GCAllocContext, /*pointer*/, Pointer, offsetof(gc_alloc_context, alloc_ptr))

‎src/coreclr/inc/dacvars.h‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -140,7 +140,7 @@ DEFINE_DACVAR(ProfControlBlock, dac__g_profControlBlock, ::g_profControlBlock)
140140
DEFINE_DACVAR(PTR_DWORD, dac__g_card_table, ::g_card_table)
141141
DEFINE_DACVAR(PTR_BYTE, dac__g_lowest_address, ::g_lowest_address)
142142
DEFINE_DACVAR(PTR_BYTE, dac__g_highest_address, ::g_highest_address)
143-
DEFINE_DACVAR(gc_alloc_context, dac__g_global_alloc_context, ::g_global_alloc_context)
143+
DEFINE_DACVAR(ee_alloc_context, dac__g_global_alloc_context, ::g_global_alloc_context)
144144

145145
DEFINE_DACVAR(IGCHeap, dac__g_pGCHeap, ::g_pGCHeap)
146146

‎src/coreclr/vm/amd64/JitHelpers_Slow.asm‎

Lines changed: 15 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -180,15 +180,15 @@ LEAF_ENTRY JIT_TrialAllocSFastSP, _TEXT
180180
inc [g_global_alloc_lock]
181181
jnz JIT_NEW
182182

183-
mov rax, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr] ; alloc_ptr
184-
mov r10, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_limit] ; limit_ptr
183+
mov rax, [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr] ; alloc_ptr
184+
mov r10, [g_global_alloc_context + OFFSETOF__ee_alloc_context__combined_limit] ; combined_limit
185185

186186
add r8, rax
187187

188188
cmp r8, r10
189189
ja AllocFailed
190190

191-
mov qword ptr [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr], r8 ; update the alloc ptr
191+
mov qword ptr [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr], r8 ; update the alloc ptr
192192
mov [rax], rcx
193193
mov [g_global_alloc_lock], -1
194194

@@ -208,8 +208,8 @@ NESTED_ENTRY JIT_BoxFastUP, _TEXT
208208
inc [g_global_alloc_lock]
209209
jnz JIT_Box
210210

211-
mov rax, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr] ; alloc_ptr
212-
mov r10, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_limit] ; limit_ptr
211+
mov rax, [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr] ; alloc_ptr
212+
mov r10, [g_global_alloc_context + OFFSETOF__ee_alloc_context__combined_limit] ; combined_limit
213213

214214
add r8, rax
215215

@@ -219,7 +219,7 @@ NESTED_ENTRY JIT_BoxFastUP, _TEXT
219219
test rdx, rdx
220220
je NullRef
221221

222-
mov qword ptr [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr], r8 ; update the alloc ptr
222+
mov qword ptr [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr], r8 ; update the alloc ptr
223223
mov [rax], rcx
224224
mov [g_global_alloc_lock], -1
225225

@@ -287,15 +287,15 @@ LEAF_ENTRY AllocateStringFastUP, _TEXT
287287
inc [g_global_alloc_lock]
288288
jnz FramedAllocateString
289289

290-
mov rax, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr] ; alloc_ptr
291-
mov r10, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_limit] ; limit_ptr
290+
mov rax, [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr] ; alloc_ptr
291+
mov r10, [g_global_alloc_context + OFFSETOF__ee_alloc_context__combined_limit] ; combined_limit
292292

293293
add r8, rax
294294

295295
cmp r8, r10
296296
ja AllocFailed
297297

298-
mov qword ptr [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr], r8 ; update the alloc ptr
298+
mov qword ptr [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr], r8 ; update the alloc ptr
299299
mov [rax], r11
300300
mov [g_global_alloc_lock], -1
301301

@@ -343,16 +343,16 @@ LEAF_ENTRY JIT_NewArr1VC_UP, _TEXT
343343
inc [g_global_alloc_lock]
344344
jnz JIT_NewArr1
345345

346-
mov rax, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr] ; alloc_ptr
347-
mov r10, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_limit] ; limit_ptr
346+
mov rax, [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr] ; alloc_ptr
347+
mov r10, [g_global_alloc_context + OFFSETOF__ee_alloc_context__combined_limit] ; combined_limit
348348

349349
add r8, rax
350350
jc AllocFailed
351351

352352
cmp r8, r10
353353
ja AllocFailed
354354

355-
mov qword ptr [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr], r8 ; update the alloc ptr
355+
mov qword ptr [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr], r8 ; update the alloc ptr
356356
mov [rax], rcx
357357
mov [g_global_alloc_lock], -1
358358

@@ -396,15 +396,15 @@ LEAF_ENTRY JIT_NewArr1OBJ_UP, _TEXT
396396
inc [g_global_alloc_lock]
397397
jnz JIT_NewArr1
398398

399-
mov rax, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr] ; alloc_ptr
400-
mov r10, [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_limit] ; limit_ptr
399+
mov rax, [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr] ; alloc_ptr
400+
mov r10, [g_global_alloc_context + OFFSETOF__ee_alloc_context__combined_limit] ; combined_limit
401401

402402
add r8, rax
403403

404404
cmp r8, r10
405405
ja AllocFailed
406406

407-
mov qword ptr [g_global_alloc_context + OFFSETOF__gc_alloc_context__alloc_ptr], r8 ; update the alloc ptr
407+
mov qword ptr [g_global_alloc_context + OFFSETOF__ee_alloc_context__alloc_ptr], r8 ; update the alloc ptr
408408
mov [rax], rcx
409409
mov [g_global_alloc_lock], -1
410410

‎src/coreclr/vm/amd64/asmconstants.h‎

Lines changed: 5 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -111,11 +111,12 @@ ASMCONSTANTS_C_ASSERT(OFFSETOF__Thread__m_pFrame
111111
#define Thread_m_pFrame OFFSETOF__Thread__m_pFrame
112112

113113

114-
#define OFFSETOF__gc_alloc_context__alloc_ptr 0x0
115-
ASMCONSTANT_OFFSETOF_ASSERT(gc_alloc_context, alloc_ptr);
114+
#define OFFSETOF__ee_alloc_context__alloc_ptr 0x8
115+
ASMCONSTANTS_C_ASSERT(OFFSETOF__ee_alloc_context__alloc_ptr == offsetof(ee_alloc_context, gc_allocation_context) +
116+
offsetof(gc_alloc_context, alloc_ptr));
116117

117-
#define OFFSETOF__gc_alloc_context__alloc_limit 0x8
118-
ASMCONSTANT_OFFSETOF_ASSERT(gc_alloc_context, alloc_limit);
118+
#define OFFSETOF__ee_alloc_context__combined_limit 0x0
119+
ASMCONSTANTS_C_ASSERT(OFFSETOF__ee_alloc_context__combined_limit == offsetof(ee_alloc_context, combined_limit));
119120

120121
#define OFFSETOF__ThreadExceptionState__m_pCurrentTracker 0x000
121122
ASMCONSTANTS_C_ASSERT(OFFSETOF__ThreadExceptionState__m_pCurrentTracker

‎src/coreclr/vm/comutilnative.cpp‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -848,7 +848,7 @@ FCIMPL0(INT64, GCInterface::GetAllocatedBytesForCurrentThread)
848848

849849
INT64 currentAllocated = 0;
850850
Thread *pThread = GetThread();
851-
gc_alloc_context* ac = &t_runtime_thread_locals.alloc_context;
851+
gc_alloc_context* ac = &t_runtime_thread_locals.alloc_context.gc_allocation_context;
852852
currentAllocated = ac->alloc_bytes + ac->alloc_bytes_uoh - (ac->alloc_limit - ac->alloc_ptr);
853853

854854
return currentAllocated;

‎src/coreclr/vm/gccover.cpp‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1834,7 +1834,7 @@ void DoGcStress (PCONTEXT regs, NativeCodeVersion nativeCodeVersion)
18341834
// BUG(github #10318) - when not using allocation contexts, the alloc lock
18351835
// must be acquired here. Until fixed, this assert prevents random heap corruption.
18361836
assert(GCHeapUtilities::UseThreadAllocationContexts());
1837-
GCHeapUtilities::GetGCHeap()->StressHeap(&t_runtime_thread_locals.alloc_context);
1837+
GCHeapUtilities::GetGCHeap()->StressHeap(&t_runtime_thread_locals.alloc_context.gc_allocation_context);
18381838

18391839
// StressHeap can exit early w/o forcing a SuspendEE to trigger the instruction update
18401840
// We can not rely on the return code to determine if the instruction update happened

‎src/coreclr/vm/gcenv.ee.cpp‎

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -443,7 +443,14 @@ gc_alloc_context * GCToEEInterface::GetAllocContext()
443443
return nullptr;
444444
}
445445

446-
return &t_runtime_thread_locals.alloc_context;
446+
return &t_runtime_thread_locals.alloc_context.gc_allocation_context;
447+
}
448+
449+
void InvokeGCAllocCallback(ee_alloc_context* pEEAllocContext, enum_alloc_context_func* fn, void* param)
450+
{
451+
gc_alloc_context* pAllocContext = &pEEAllocContext->gc_allocation_context;
452+
fn(pAllocContext, param);
453+
pEEAllocContext->UpdateCombinedLimit();
447454
}
448455

449456
void GCToEEInterface::GcEnumAllocContexts(enum_alloc_context_func* fn, void* param)
@@ -460,16 +467,16 @@ void GCToEEInterface::GcEnumAllocContexts(enum_alloc_context_func* fn, void* par
460467
Thread * pThread = NULL;
461468
while ((pThread = ThreadStore::GetThreadList(pThread)) != NULL)
462469
{
463-
gc_alloc_context* palloc_context = pThread->GetAllocContext();
470+
ee_alloc_context* palloc_context = pThread->GetEEAllocContext();
464471
if (palloc_context != nullptr)
465472
{
466-
fn(palloc_context, param);
473+
InvokeGCAllocCallback(palloc_context, fn, param);
467474
}
468475
}
469476
}
470477
else
471478
{
472-
fn(&g_global_alloc_context, param);
479+
InvokeGCAllocCallback(&g_global_alloc_context, fn, param);
473480
}
474481
}
475482

‎src/coreclr/vm/gcheaputilities.cpp‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -41,7 +41,7 @@ bool g_sw_ww_enabled_for_gc_heap = false;
4141

4242
#endif // FEATURE_USE_SOFTWARE_WRITE_WATCH_FOR_GC_HEAP
4343

44-
GVAL_IMPL_INIT(gc_alloc_context, g_global_alloc_context, {});
44+
GVAL_IMPL_INIT(ee_alloc_context, g_global_alloc_context, {});
4545

4646
enum GC_LOAD_STATUS {
4747
GC_LOAD_STATUS_BEFORE_START,

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