From e3a047249791a77ab088c01bcf0a1cda7cd8259d Mon Sep 17 00:00:00 2001
From: Shubham Verma <shubhamv.sv@gmail.com>
Date: Wed, 29 Jan 2025 13:37:21 -0500
Subject: [PATCH] Add object model API to get minimum object size

Signed-off-by: Shubham Verma <shubhamv.sv@gmail.com>
---
 .../control/JITClientCompilationThread.cpp         |  1 +
 runtime/compiler/env/J9ObjectModel.cpp             | 14 ++++++++++++++
 runtime/compiler/env/J9ObjectModel.hpp             |  5 ++++-
 runtime/compiler/runtime/JITClientSession.hpp      |  1 +
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/runtime/compiler/control/JITClientCompilationThread.cpp b/runtime/compiler/control/JITClientCompilationThread.cpp
index 5f0ae628a19..299d7165d1e 100644
--- a/runtime/compiler/control/JITClientCompilationThread.cpp
+++ b/runtime/compiler/control/JITClientCompilationThread.cpp
@@ -523,6 +523,7 @@ handleServerMessage(JITServer::ClientStream *client, TR_J9VM *fe, JITServer::Mes
          vmInfo._osrGlobalBufferSize = javaVM->osrGlobalBufferSize;
          vmInfo._needsMethodTrampolines = TR::CodeCacheManager::instance()->codeCacheConfig().needsMethodTrampolines();
          vmInfo._objectAlignmentInBytes = TR::Compiler->om.objectAlignmentInBytes();
+         vmInfo._minimumObjectSizeInBytes = TR::Compiler->om.getMinimumObjectSizeInBytes();
          vmInfo._isGetImplAndRefersToInliningSupported = fe->isGetImplAndRefersToInliningSupported();
          vmInfo._isAllocateZeroedTLHPagesEnabled = fe->tlhHasBeenCleared();
          vmInfo._staticObjectAllocateFlags = fe->getStaticObjectFlags();
diff --git a/runtime/compiler/env/J9ObjectModel.cpp b/runtime/compiler/env/J9ObjectModel.cpp
index f8cf8a3cc75..f9b9e921b48 100644
--- a/runtime/compiler/env/J9ObjectModel.cpp
+++ b/runtime/compiler/env/J9ObjectModel.cpp
@@ -102,6 +102,7 @@ J9::ObjectModel::initialize()
       }
 
    _objectAlignmentInBytes = objectAlignmentInBytes();
+   _minimumObjectSizeInBytes = mmf->j9gc_modron_getConfigurationValueForKey(vm, j9gc_modron_configuration_minimumObjectSize, &result) ? result : 0;
    }
 
 
@@ -842,3 +843,16 @@ J9::ObjectModel::getObjectAlignmentInBytes()
 #endif /* defined(J9VM_OPT_JITSERVER) */
    return _objectAlignmentInBytes;
 }
+
+int32_t
+J9::ObjectModel::getMinimumObjectSizeInBytes()
+{
+#if defined(J9VM_OPT_JITSERVER)
+   if (auto stream = TR::CompilationInfo::getStream())
+      {
+      auto *vmInfo = TR::compInfoPT->getClientData()->getOrCacheVMInfo(stream);
+      return vmInfo->_minimumObjectSizeInBytes;
+      }
+#endif /* defined(J9VM_OPT_JITSERVER) */
+   return _minimumObjectSizeInBytes;
+}
diff --git a/runtime/compiler/env/J9ObjectModel.hpp b/runtime/compiler/env/J9ObjectModel.hpp
index e235b04db21..c7607df0280 100644
--- a/runtime/compiler/env/J9ObjectModel.hpp
+++ b/runtime/compiler/env/J9ObjectModel.hpp
@@ -55,7 +55,8 @@ class ObjectModel : public OMR::ObjectModelConnector
       _arrayLetLeafLogSize(0),
       _readBarrierType(gc_modron_readbar_none),
       _writeBarrierType(gc_modron_wrtbar_none),
-      _objectAlignmentInBytes(0)
+      _objectAlignmentInBytes(0),
+      _minimumObjectSizeInBytes(0)
    {}
 
    void initialize();
@@ -157,6 +158,7 @@ class ObjectModel : public OMR::ObjectModelConnector
    bool compressObjectReferences();
 
    int32_t getObjectAlignmentInBytes();
+   int32_t getMinimumObjectSizeInBytes();
 
 private:
 
@@ -167,6 +169,7 @@ class ObjectModel : public OMR::ObjectModelConnector
    MM_GCReadBarrierType  _readBarrierType;
    MM_GCWriteBarrierType _writeBarrierType;
    int32_t               _objectAlignmentInBytes;
+   int32_t               _minimumObjectSizeInBytes;
    };
 
 }
diff --git a/runtime/compiler/runtime/JITClientSession.hpp b/runtime/compiler/runtime/JITClientSession.hpp
index d3ffca20207..ecd3c29e5e0 100644
--- a/runtime/compiler/runtime/JITClientSession.hpp
+++ b/runtime/compiler/runtime/JITClientSession.hpp
@@ -312,6 +312,7 @@ class ClientSessionData
       UDATA _osrGlobalBufferSize;
       bool _needsMethodTrampolines;
       int32_t _objectAlignmentInBytes;
+      int32_t _minimumObjectSizeInBytes;
       bool _isGetImplAndRefersToInliningSupported;
       bool _isAllocateZeroedTLHPagesEnabled;
       uint32_t _staticObjectAllocateFlags;