[cDAC] Add GC stress verification infrastructure and stack walk fixes

docs/design/datacontracts/StackWalk.md

@@ -57,6 +57,9 @@ This contract depends on the following descriptors:
 | `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
 | `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
 | `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
+| `StubDispatchFrame` | `GCRefMap` | Cached pointer to GC reference map blob for caller stack promotion |
+| `ExternalMethodFrame` | `GCRefMap` | Cached pointer to GC reference map blob for caller stack promotion |
+| `DynamicHelperFrame` | `DynamicHelperFrameFlags` | Flags indicating which argument registers contain GC references |
 | `TransitionBlock` | `ReturnAddress` | Return address associated with the TransitionBlock |
 | `TransitionBlock` | `CalleeSavedRegisters` | Platform specific CalleeSavedRegisters struct associated with the TransitionBlock |
 | `TransitionBlock` (arm) | `ArgumentRegisters` | ARM specific `ArgumentRegisters` struct |
@@ -87,6 +90,9 @@ Global variables used:
 | Global Name | Type | Purpose |
 | --- | --- | --- |
 | For each FrameType `<frameType>`, `<frameType>##Identifier` | `FrameIdentifier` enum value | Identifier used to determine concrete type of Frames |
+| `TransitionBlockOffsetOfFirstGCRefMapSlot` | `uint32` | Byte offset within TransitionBlock where GCRefMap slot enumeration begins. ARM64: RetBuffArgReg offset; others: ArgumentRegisters offset. |
+| `TransitionBlockOffsetOfArgumentRegisters` | `uint32` | Byte offset of the ArgumentRegisters within the TransitionBlock |
+| `TransitionBlockOffsetOfArgs` | `uint32` | Byte offset of stack arguments (first arg after registers) = `sizeof(TransitionBlock)` |
 
 Constants used:
 | Source | Name | Value | Purpose |

eng/Subsets.props

@@ -254,6 +254,7 @@
     <SubsetName Include="Tools.ILLinkTests" OnDemand="true" Description="Unit tests for the tools.illink subset." />
     <SubsetName Include="Tools.CdacTests" OnDemand="true" Description="Unit tests for the diagnostic data contract reader." />
     <SubsetName Include="Tools.CdacDumpTests" OnDemand="true" Description="Dump-based integration tests for the diagnostic data contract reader." />
+    <SubsetName Include="Tools.CdacGCStressTests" OnDemand="true" Description="GC stress integration tests for the diagnostic data contract reader." />
     <SubsetName Include="Tools.ILAsm" OnDemand="true" Description="Build only the managed ilasm tool." />
 
     <!-- Host -->
@@ -528,6 +529,10 @@
     <ProjectToBuild Include="$(SharedNativeRoot)managed\cdac\tests\DumpTests\Microsoft.Diagnostics.DataContractReader.DumpTests.csproj" Test="true" Category="tools"/>
   </ItemGroup>
 
+  <ItemGroup Condition="$(_subset.Contains('+tools.cdacgcstresstests+'))">
+    <ProjectToBuild Include="$(SharedNativeRoot)managed\cdac\tests\GCStressTests\Microsoft.Diagnostics.DataContractReader.GCStressTests.csproj" Test="true" Category="tools"/>
+  </ItemGroup>
+
   <ItemGroup Condition="$(_subset.Contains('+tools.illink+'))">
     <ProjectToBuild Include="$(ToolsProjectRoot)illink\src\linker\Mono.Linker.csproj" Category="tools" />
     <ProjectToBuild Include="$(ToolsProjectRoot)illink\src\ILLink.Tasks\ILLink.Tasks.csproj" Category="tools" />

src/coreclr/inc/clrconfigvalues.h

@@ -286,7 +286,7 @@ RETAIL_CONFIG_DWORD_INFO(INTERNAL_JitEnableNoWayAssert, W("JitEnableNoWayAssert"
 
 RETAIL_CONFIG_DWORD_INFO(UNSUPPORTED_JitFramed, W("JitFramed"), 0, "Forces EBP frames")
 CONFIG_DWORD_INFO(INTERNAL_JitThrowOnAssertionFailure, W("JitThrowOnAssertionFailure"), 0, "Throw managed exception on assertion failures during JIT instead of failfast")
-CONFIG_DWORD_INFO(INTERNAL_JitGCStress, W("JitGCStress"), 0, "GC stress mode for jit")
+CONFIG_DWORD_INFO(INTERNAL_JitGCStress, W("JitGCStress"), 0, "cDAC stress mode for jit")
 CONFIG_DWORD_INFO(INTERNAL_JitHeartbeat, W("JitHeartbeat"), 0, "")
 RETAIL_CONFIG_DWORD_INFO(UNSUPPORTED_JITMinOpts, W("JITMinOpts"), 0, "Forces MinOpts")
 
@@ -747,8 +747,10 @@ CONFIG_STRING_INFO(INTERNAL_PerfTypesToLog, W("PerfTypesToLog"), "Log facility L
 CONFIG_STRING_INFO(INTERNAL_PrestubGC, W("PrestubGC"), "")
 CONFIG_STRING_INFO(INTERNAL_PrestubHalt, W("PrestubHalt"), "")
 RETAIL_CONFIG_STRING_INFO(EXTERNAL_RestrictedGCStressExe, W("RestrictedGCStressExe"), "")
-RETAIL_CONFIG_DWORD_INFO(INTERNAL_GCStressCdacFailFast, W("GCStressCdacFailFast"), 0, "If nonzero, assert on cDAC/runtime GC ref mismatch during GC stress (GCSTRESS_CDAC mode).")
-RETAIL_CONFIG_STRING_INFO(INTERNAL_GCStressCdacLogFile, W("GCStressCdacLogFile"), "Log file path for cDAC GC stress verification results.")
+RETAIL_CONFIG_DWORD_INFO(INTERNAL_CdacStressFailFast, W("CdacStressFailFast"), 0, "If nonzero, assert on cDAC/runtime GC ref mismatch during cDAC stress (GCSTRESS_CDAC mode).")
+RETAIL_CONFIG_STRING_INFO(INTERNAL_CdacStressLogFile, W("CdacStressLogFile"), "Log file path for cDAC cDAC stress verification results.")
+RETAIL_CONFIG_DWORD_INFO(INTERNAL_CdacStressStep, W("CdacStressStep"), 1, "Verify every Nth cDAC stress point (1=every point, 100=every 100th). Reduces overhead while maintaining code path diversity.")
+RETAIL_CONFIG_DWORD_INFO(INTERNAL_CdacStress, W("CdacStress"), 0, "Enable cDAC stack reference verification. Bit flags: 0x1=alloc points, 0x2=GC trigger points, 0x4=unique stacks only, 0x8=instruction points.")
 CONFIG_DWORD_INFO(INTERNAL_ReturnSourceTypeForTesting, W("ReturnSourceTypeForTesting"), 0, "Allows returning the (internal only) source type of an IL to Native mapping for debugging purposes")
 RETAIL_CONFIG_DWORD_INFO(UNSUPPORTED_RSStressLog, W("RSStressLog"), 0, "Allows turning on logging for RS startup")
 CONFIG_DWORD_INFO(INTERNAL_SBDumpOnNewIndex, W("SBDumpOnNewIndex"), 0, "Used for Syncblock debugging. It's been a while since any of those have been used.")

src/coreclr/vm/CMakeLists.txt

@@ -329,7 +329,7 @@ set(VM_SOURCES_WKS
     finalizerthread.cpp
     floatdouble.cpp
     floatsingle.cpp
-    cdacgcstress.cpp
+    cdacstress.cpp
     frozenobjectheap.cpp
     gccover.cpp
     gcenv.ee.cpp