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Merged
tommcdon merged 7 commits into from
Mar 20, 2026
Merged

Avoid writing jitdump code for block data #122274

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0846b49
Avoid writing jitdump code for block data
tommcdon Dec 7, 2025
571b734
Address PR feedback
tommcdon Feb 5, 2026
f0df6e6
Merge branch 'main' into dev/tommcdon/jitmap_blockdata_fix
tommcdon Feb 11, 2026
bc2db43
Address PR feedback
tommcdon Feb 11, 2026
d2af966
Merge branch 'main' into dev/tommcdon/jitmap_blockdata_fix
tommcdon Feb 11, 2026
18613bb
Add comment stating why we don't report block allocations
tommcdon Mar 10, 2026
ecf365e
Merge branch 'main' into dev/tommcdon/jitmap_blockdata_fix
tommcdon Mar 19, 2026
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2 changes: 1 addition & 1 deletion src/coreclr/pal/inc/pal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -378,7 +378,7 @@ PALIMPORT
int
PALAPI
// Log a method to the jitdump file.
PAL_PerfJitDump_LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo);
PAL_PerfJitDump_LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo, bool reportCodeBlock);

PALIMPORT
int
Expand Down
17 changes: 8 additions & 9 deletions src/coreclr/pal/src/misc/perfjitdump.cpp
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Expand Up @@ -247,7 +247,7 @@ struct PerfJitDumpState
return 0;
}

int LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo)
int LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo, bool reportCodeBlock)
{
int result = 0;

Expand All @@ -257,7 +257,9 @@ struct PerfJitDumpState

JitCodeLoadRecord record;

size_t bytesRemaining = sizeof(JitCodeLoadRecord) + symbolLen + 1 + codeSize;
size_t reportedCodeSize = reportCodeBlock ? codeSize : 0;

size_t bytesRemaining = sizeof(JitCodeLoadRecord) + symbolLen + 1 + reportedCodeSize;

record.header.timestamp = GetTimeStampNS();
record.vma = (uint64_t) pCode;
Expand All @@ -269,15 +271,12 @@ struct PerfJitDumpState
// ToDo insert debugInfo and unwindInfo record items immediately before the JitCodeLoadRecord.
{ &record, sizeof(JitCodeLoadRecord) },
{ (void *)symbol, symbolLen + 1 },
{ pCode, codeSize },
{ pCode, reportedCodeSize },
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tommcdon marked this conversation as resolved.
};
size_t itemsCount = sizeof(items) / sizeof(items[0]);

size_t itemsWritten = 0;

if (result != 0)
return FatalError();

if (!enabled)
goto exit;

Expand Down Expand Up @@ -390,9 +389,9 @@ PAL_PerfJitDump_IsStarted()

int
PALAPI
PAL_PerfJitDump_LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo)
PAL_PerfJitDump_LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo, bool reportCodeBlock)
{
return GetState().LogMethod(pCode, codeSize, symbol, debugInfo, unwindInfo);
return GetState().LogMethod(pCode, codeSize, symbol, debugInfo, unwindInfo, reportCodeBlock);
}

int
Expand Down Expand Up @@ -420,7 +419,7 @@ PAL_PerfJitDump_IsStarted()

int
PALAPI
PAL_PerfJitDump_LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo)
PAL_PerfJitDump_LogMethod(void* pCode, size_t codeSize, const char* symbol, void* debugInfo, void* unwindInfo, bool reportCodeBlock)
{
return 0;
}
Expand Down
15 changes: 11 additions & 4 deletions src/coreclr/vm/perfmap.cpp
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Expand Up @@ -339,7 +339,7 @@ void PerfMap::LogJITCompiledMethod(MethodDesc * pMethod, PCODE pCode, size_t cod
s_Current->WriteLine(line);
}

PAL_PerfJitDump_LogMethod((void*)pCode, codeSize, name.GetUTF8(), nullptr, nullptr);
PAL_PerfJitDump_LogMethod((void*)pCode, codeSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
}
}
EX_CATCH{} EX_END_CATCH
Expand Down Expand Up @@ -380,7 +380,7 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
if (methodRegionInfo.hotSize > 0)
{
CrstHolder ch(&(s_csPerfMap));
PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.hotStartAddress, methodRegionInfo.hotSize, name.GetUTF8(), nullptr, nullptr);
PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.hotStartAddress, methodRegionInfo.hotSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
}

if (methodRegionInfo.coldSize > 0)
Expand All @@ -393,7 +393,7 @@ void PerfMap::LogPreCompiledMethod(MethodDesc * pMethod, PCODE pCode)
name.Append(W("[PreJit-cold]"));
}

PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr);
PAL_PerfJitDump_LogMethod((void*)methodRegionInfo.coldStartAddress, methodRegionInfo.coldSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/true);
}
}
EX_CATCH{} EX_END_CATCH
Expand Down Expand Up @@ -450,7 +450,14 @@ void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode,
s_Current->WriteLine(line);
}

PAL_PerfJitDump_LogMethod((void*)pCode, codeSize, name.GetUTF8(), nullptr, nullptr);
// For block-level stub allocations, the memory may be reserved but not yet committed.
// Emitting code bytes in that case can cause jitdump logging to fail, and the bytes
// are optional in the jitdump specification.
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//
// Even when the memory is committed, block-level stubs are reported at commit time
// before the actual stub code has been written, so the code bytes would be zeros or
// uninitialized. We therefore skip code bytes for block allocations entirely.
PAL_PerfJitDump_LogMethod((void*)pCode, codeSize, name.GetUTF8(), nullptr, nullptr, /*reportCodeBlock*/ stubAllocationType != PerfMapStubType::Block);
}
}
EX_CATCH{} EX_END_CATCH
Expand Down
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