Convert all FCalls with HELPER_METHOD_FRAME to QCalls

[jkotas]

Benefits:

• Performance: QCalls are generally faster than FCalls with HELPER_METHOD_FRAME
• Eliminate duplication: These are redundant mechanism. Once all of them are converted, we can eliminate the duplication.
• Complexity of stackwalking algorithm: HELPER_METHOD_FRAMEs make the stackwalking algorithm with all its dependencies more complicated than it needs to be. (See nibblemapmacros do a linear scan #93550 for more context.)
  • We want to work towards unification of CoreCLR stackwalker and native AOT stackwalker. Native AOT has much simpler stackwalker and it does not have HELPER_METHOD_FRAMEs.

Work

List of JIT helpers that need the removal of explicit HMFs:

• JIT_GetFieldAddr_Framed, JIT_NewMDArr Remove HMFs from JIT helpers #111034
• JIT_New Share allocation helpers between CoreCLR and NativeAOT #115339
• JIT_NewMaybeFrozen Share allocation helpers between CoreCLR and NativeAOT #115339
• FramedAllocateString Share allocation helpers between CoreCLR and NativeAOT #115339
• JIT_StrCns Convert JitHelper JIT_StrCns to QCall #113674
• JIT_NewArr1 Share allocation helpers between CoreCLR and NativeAOT #115339
• JIT_NewArr1MaybeFrozen Share allocation helpers between CoreCLR and NativeAOT #115339
• JIT_Box Convert JIT_Box* to C# #115134
• JIT_StressGC, JIT_GetRuntimeFieldStub, JIT_GetRuntimeMethodStub Remove HMFs from JIT helpers #111088
• JIT_UserBreakpoint JIT_GetRuntimeType_Framed Remove HMFs from JIT helpers #111134
• JIT_MonEnter_Helper Remove helper method frames from Monitors #113242
• JIT_MonTryEnter_Helper Remove helper method frames from Monitors #113242
• JIT_MonExit_Helper Remove helper method frames from Monitors #113242
• JIT_MonExit_Signal Remove helper method frames from Monitors #113242
• IL_Throw, IL_Rethrow Remove HMF from IL_Throw/IL_ThrowExact/IL_Rethrow #115253
• JIT_ThrowMethodAccessException, JIT_ThrowFieldAccessException, JIT_ThrowClassAccessException Remove HMFs from JIT helpers #111075
• JIT_PollGC_Framed Gc enter/leave/poll without HELPER_METHOD_FRAME #109378
• JIT_PInvokeEndRarePath Gc enter/leave/poll without HELPER_METHOD_FRAME #109378
• JIT_RareDisableHelper/JIT_RareDisableHelperWorker Gc enter/leave/poll without HELPER_METHOD_FRAME #109378
• JIT_Patchpoint_Framed Replace HELPER_METHOD_FRAME with DynamicHelperFrame in patchpoints #112025
• JIT_PartialCompilationPatchpoint Replace HELPER_METHOD_FRAME with DynamicHelperFrame in patchpoints #112025

List of JIT helpers with implicit HMFs through a use of FCThrow.

• JIT_Div, JIT_Mod, JIT_UDiv, JIT_UMod, JIT_LDiv, JIT_LMod, JIT_ULDiv, JIT_ULMod - Move arithmetic helpers to managed code #109087 or Alternate approach for HELPER_METHOD_FRAME removal for arithmetic div… #113286

Remove all remaining explicit calls to GCPoll (that is, FC_GC_POLL and FC_GC_POLL_RET):

• Buffer::BulkMoveWithWriteBarrier, GCInterface::SuppressFinalize, GCInterface::GetGenerationInternal, GCInterface::GetSegmentSize, GCInterface::CollectionCount, ObjectNative::ContentEquals - Remove all explicit GC Poll calls in unmanaged code. #113715

The following clean-up can occur after all the above is complete:

• Removal of any HELPER_METHOD_FRAME related infrastrcture in fcall.h and fcall.cpp Cleanup HMF definitions #116085
• Update BoTR to remove description of the HELPER_METHOD_FRAME concept. Cleanup HMF definitions #116085

[hughbe]

This is cool! Is the plan to eventually remove FCall functionality from the runtime?

[danmoseley]

Good to see you around here again @hughbe! 😀

[jkotas]

Is the plan to eventually remove FCall functionality from the runtime?

FCalls with HELPER_METHOD_FRAME. I think FCalls without HELPER_METHOD_FRAME are needed for perf reasons.

[davidwrighton]

I think we also might be able to move to QCalls with SuppressGCTransition instead of FCalls without HELPER_METHOD_FRAME for the perf critical ones, but that's a bridge to examine and consider crossing once we've removed HELPER_METHOD_FRAME from the situation.

[jkotas]

I think we also might be able to move to QCalls with SuppressGCTransition instead of FCalls without HELPER_METHOD_FRAME for the perf critical ones, but that's a bridge to examine and consider crossing once we've removed HELPER_METHOD_FRAME from the situation.

I agree. It would require modifying rules for how GC tracked pointers are passed to and from P/Invokes and we would need to deal with managed/unmanaged calling convention differences somehow. I think it would be just a cosmetic change at the end. It would not be a significant simplification of the system (compared to getting rid of HELPER_METHOD_FRAMEs).