[IR Container] Phase 2.3 Basic shared ptr

[mdavis36]

Change Fusion::ir_container_ from unique_ptr to shared_ptr to enable future container sharing between Fusions. Add Fusion tracking API to IrContainer (addFusion/removeFusion/transferFusion/sharingCount). Disable parallel compilation during the shared_ptr transition.

[mdavis36]

!test

[github-actions]

Review updated until commit f8ff364

Description

• Transition Fusion::ir_container_ from unique_ptr to shared_ptr for container sharing

• Add Fusion tracking API to IrContainer (addFusion/removeFusion/transferFusion/sharingCount)

• Remove IrContainer::parent_ since 1:1 relationship no longer holds

• Disable parallel compilation during shared_ptr transition with kPhase2DisableParallelCompile flag

Changes walkthrough

	Relevant files
Enhancement	fusion.cpp Transition Fusion to shared_ptr IrContainer                            csrc/fusion.cpp Change ir_container_ from unique_ptr to shared_ptr Remove parent_ pointer updates in swap function Update constructor to use addFusion(this) and make_shared Update destructor to call removeFusion(this) Update IrCloner copy call to pass dest_fusion parameter Update inContainer check to use sharing_fusions_ instead of parent_ +8/-10    container.cpp Add Fusion tracking infrastructure to IrContainer                csrc/ir/container.cpp Remove parent_ member variable and swap updates Update copy function to accept dest_fusion parameter Add new Fusion tracking API methods (addFusion/removeFusion/transferFusion/sharingCount/hasMultipleFusions/sharingFusions) Update inContainer to check sharing_fusions_ instead of parent_ +31/-5    fusion.h Update Fusion header for shared_ptr transition                      csrc/fusion.h Change ir_container_ member from unique_ptr to shared_ptr Add ir_container_ptr() method to access shared_ptr +5/-2      container.h Update IrContainer header for shared_ptr and tracking        csrc/ir/container.h Remove parent_ member variable Update copy function signature to accept dest_fusion parameter Add Fusion tracking API declarations +11/-9
Configuration changes	fusion_kernel_runtime.cpp Disable parallel compilation during shared_ptr transition csrc/runtime/fusion_kernel_runtime.cpp Add kPhase2DisableParallelCompile constant set to true Use constant to disable parallel compilation in compileFusionParallel Use constant to disable parallel compilation in error handling +7/-2

PR Reviewer Guide

Here are some key observations to aid the review process:

🧪 PR contains tests

⚡ Recommended focus areas for review

Memory Management Safety The transition from unique_ptr to shared_ptr requires careful validation of ownership semantics. The removeFusion call in the destructor needs to be verified to prevent dangling references and ensure proper cleanup when multiple fusions share the same container. Fusion::~Fusion() { clear(); if (ir_container_) { ir_container_->removeFusion(this); } } Container Sharing Logic The new sharing_fusions_ tracking mechanism needs validation to ensure it correctly handles fusion addition, removal, and transfer operations. The hasMultipleFusions() and sharingCount() functions should be tested with various fusion sharing scenarios. void IrContainer::addFusion(Fusion* fusion) { sharing_fusions_.insert(fusion); } void IrContainer::removeFusion(Fusion* fusion) { sharing_fusions_.erase(fusion); } void IrContainer::transferFusion(Fusion* from, Fusion* to) { sharing_fusions_.erase(from); sharing_fusions_.insert(to); } size_t IrContainer::sharingCount() const { return sharing_fusions_.size(); } bool IrContainer::hasMultipleFusions() const { return sharing_fusions_.size() > 1; } const std::unordered_set<Fusion*>& IrContainer::sharingFusions() const { return sharing_fusions_; } Performance Impact The kPhase2DisableParallelCompile flag disables parallel compilation which may significantly impact performance. This should be temporary, but the PR should include performance benchmarks or at least acknowledge the performance regression during this transition phase. // TODO: Remove when std::shared_mutex is added to IrContainer. constexpr bool kPhase2DisableParallelCompile = true;