debug: log propagation details

[wujingyue]

Summary

• add debug logging hooks for propagation paths
• adjust related scheduler/propagation utilities

Testing

• not run

[github-actions]

Review updated until commit 080fdea

Description

• Add debug logging for sharding propagation operations

• Implement PropagateDirection enum streaming operator

• Enable TransformPropagator debug output in shardLoopLike

• Reorganize SPECIALIZE_PRINTER macros in base.h

• Remove unused multidevice/utils.h include

Changes walkthrough

	Relevant files
Enhancement	propagation.cpp Add debug logging to shardLoopLike function                            csrc/multidevice/propagation.cpp Added base.h include for debug utilities Added debug logging in shardLoopLike function to log propagation details Logs ref/target tensors, direction, and selected parallel types when debug enabled +7/-0      utils.cpp Implement PropagateDirection streaming operator                    csrc/scheduler/utils.cpp Added std::ostream& operator<< overload for PropagateDirection enum Enables string representation of propagation direction for debugging +16/-0    utils.h Add PropagateDirection operator declaration                            csrc/scheduler/utils.h Added forward declaration of operator<< for PropagateDirection Enables proper compilation of streaming operator in utils.cpp +2/-0
Cleanup	propagate_shardings.cpp Remove unused include directive                                                    csrc/preseg_passes/propagate_shardings.cpp Removed unused #include "multidevice/utils.h" +0/-1
Formatting	base.h Reorganize SPECIALIZE_PRINTER macros                                          csrc/base.h Reorganized SPECIALIZE_PRINTER macro declarations Added std::vector and std::vector specializations Improved alphabetical ordering of printer specializations +13/-11

PR Reviewer Guide

Here are some key observations to aid the review process:

🧪 No relevant tests

⚡ Recommended focus areas for review

Debug Logging Implementation The debug logging in shardLoopLike function uses isDebugDumpEnabled and debug() calls. Need to verify that the debug stream and debug dump option are properly initialized and that this won't cause issues in production builds where debug logging might be disabled. if (isDebugDumpEnabled(DebugDumpOption::TransformPropagator)) { debug() << "Propagating shardings from " << ref->toString() << " to " << target->toString() << " in " << direction << " for " << toDelimitedString(selected_parallel_types) << std::endl; } Missing Include Dependencies The operator<< implementation for PropagateDirection is added but it's unclear if the necessary headers for std::ostream are included. Also need to verify this doesn't conflict with other stream operators in the codebase. std::ostream& operator<<(std::ostream& os, PropagateDirection direction) { switch (direction) { case PropagateDirection::kForward: os << "Forward"; break; case PropagateDirection::kBackward: os << "Backward"; break; } return os; } Removed Include Impact The removal of "#include multidevice/utils.h" should be verified to ensure no functionality is broken. Need to check if any symbols from that header are still being used in this file after the removal. // clang-format off /* * SPDX-FileCopyrightText: Copyright (c) 2024-present NVIDIA CORPORATION & AFFILIATES. * All rights reserved. * SPDX-License-Identifier: BSD-3-Clause */ // clang-format on #include "preseg_passes/propagate_shardings.h" #include <vector> #include "ir/interface_nodes.h" #include "ir/iostream.h" #include "ir/utils.h" #include "multidevice/propagation.h" #include "scheduler/utils.h" namespace nvfuser::preseg_passes { namespace {

[greptile-apps]

Greptile Overview

Greptile Summary

This PR adds comprehensive debug logging infrastructure for propagation paths in the multidevice sharding system. The changes enable developers to trace how shardings propagate between tensor views by logging the source, target, direction (Forward/Backward), and selected parallel types.

Key Changes:

• Added debug logging hook in shardLoopLike function that outputs propagation details when TransformPropagator debug option is enabled
• Implemented operator<< for PropagateDirection enum to enable readable stream output
• Added SPECIALIZE_PRINTER(ParallelType) to support printing parallel types in debug messages
• Cleaned up include dependencies by removing unused multidevice/utils.h
• Alphabetized printer specializations for better maintainability

The implementation is clean and follows existing debugging patterns in the codebase. All required infrastructure (printer specializations, stream operators) is properly set up to support the new logging functionality.

Confidence Score: 5/5

• This PR is safe to merge - it only adds debug logging infrastructure without changing functional behavior
• All changes are non-functional debug additions with proper infrastructure support. The logging is gated behind a debug flag, the printer specializations follow existing patterns, and the operator<< implementation is complete and correct
• No files require special attention

Important Files Changed

Filename	Overview
csrc/base.h	Alphabetized SPECIALIZE_PRINTER declarations and added ParallelType for debug logging support
csrc/scheduler/utils.cpp	Implemented operator<< for PropagateDirection with Forward/Backward string conversion
csrc/multidevice/propagation.cpp	Added debug logging to shardLoopLike function showing propagation details including direction and parallel types

Sequence Diagram

sequenceDiagram
    participant Caller
    participant shardLoopLike
    participant Debug
    participant PropagateDirection
    participant ParallelType
    participant toDelimitedString
    
    Caller->>shardLoopLike: Call with ref, target, selected_parallel_types, direction
    shardLoopLike->>Debug: Check isDebugDumpEnabled(TransformPropagator)
    alt Debug enabled
        shardLoopLike->>Debug: debug() stream
        shardLoopLike->>Debug: << ref->toString()
        shardLoopLike->>Debug: << target->toString()
        shardLoopLike->>PropagateDirection: << direction (uses operator<<)
        PropagateDirection-->>shardLoopLike: Returns "Forward" or "Backward"
        shardLoopLike->>toDelimitedString: Convert selected_parallel_types
        toDelimitedString->>ParallelType: Printer<ParallelType>::toString() for each
        toDelimitedString-->>shardLoopLike: Returns delimited string
        shardLoopLike->>Debug: Output complete log message
    end
    shardLoopLike->>shardLoopLike: Continue with propagation logic

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