Poplar and PopLibs User Guide

• 1. Introduction
• 2. Programming with Poplar
  • 2.1. Poplar programming model
  • 2.2. The structure of a Poplar program
    • 2.2.1. Program flow control
      • Looping
      • Conditional execution
    • 2.2.2. What happens at run time
  • 2.3. Virtual graphs
  • 2.4. Replicated graphs
    • 2.4.1. Creating a replicated graph
  • 2.5. Data streams and remote buffers
    • 2.5.1. Data streams
      • Device-side streams
      • Host-side stream access
      • Stream buffer size limit
    • 2.5.2. Optimising host data transfers
      • Prefetch
      • Multibuffering
    • 2.5.3. Remote memory buffers
      • Remote buffer restrictions
  • 2.6. IPU-Link and sync configuration
    • 2.6.1. Link topologies
    • 2.6.2. Sync groups
  • 2.7. Device code
    • 2.7.1. Pre-compiling codelets
• 3. Understanding vertices
  • 3.1. The Vertex class
  • 3.2. Vertex state
    • 3.2.1. Vector and VectorList types
    • 3.2.2. Allowed field types as vertex state
    • 3.2.3. Specifying memory constraints
    • 3.2.4. Stack allocation
  • 3.3. MultiVertex worker threads
    • 3.3.1. Thread safety
  • 3.4. Calling conventions
    • 3.4.1. External codelets
    • 3.4.2. Recursion and function pointers
  • 3.5. Vertex name mangling
• 4. Supported types
  • 4.1. Scalar types
  • 4.2. Floating point types
    • 4.2.1. Half on the IPU
    • 4.2.2. Half on the CPU
  • 4.3. Vector types
  • 4.4. Structure types
  • 4.5. Bit fields
• 5. Vertex vector types
  • 5.1. Parameters
    • 5.1.1. Types
    • 5.1.2. Layout
    • 5.1.3. Minimum alignment
    • 5.1.4. Interleaved memory
  • 5.2. Memory layout for vectors
    • 5.2.1. Pointer compression
      • SCALED_PTR32
      • SCALED_PTR64
      • SCALED_PTR128
    • 5.2.2. Vector<T> layout
    • 5.2.3. Vector<Input<Vector<T>>> layout
    • 5.2.4. VectorList layout
      • DELTANELEMENTS layout
      • DELTAN layout
      • COMPACT_DELTAN layout
• 6. Using the Poplar library
• 7. The PopLibs libraries
  • 7.1. Using PopLibs
• 8. Graphcore Communication Library (GCL)
  • 8.1. Example
  • 8.2. Topologies
    • 8.2.1. Physical topologies
    • 8.2.2. Logical topologies
    • 8.2.3. Relationship between logical and physical topologies
• 9. Writing vertices in assembly
  • 9.1. Instruction set overview
    • 9.1.1. Supervisors and workers
    • 9.1.2. Execution pipelines
  • 9.2. Memory architecture
    • 9.2.1. Getting information about the memory
    • 9.2.2. Mk1 Colossus (GC2)
    • 9.2.3. Mk2 Colossus (GC200)
    • 9.2.4. Load and store instructions
  • 9.3. Worker stack and scratch space
    • 9.3.1. Specifying stack size
    • 9.3.2. Examples
  • 9.4. Vertex pipelines
    • 9.4.1. Memory conflicts
    • 9.4.2. Modified pipeline
    • 9.4.3. Fill and drain
  • 9.5. Assembly hints & tips
    • 9.5.1. Using the assembler
      • Assembler macros
      • Labels
      • Recording the code size of the vertex
      • Place each vertex in a unique section
    • 9.5.2. Architectural tips
      • Aligning repeat bodies
      • Over-reading and over-processing
      • Scratch space
      • Loading constants
    • 9.5.3. Division by 6
      • Division on the IPU
      • Division on the host
    • 9.5.4. General
      • Focus on optimising the vectorised case
      • Testing
      • Bit twiddling
• 10. Profiling
  • 10.1. Profiling options
    • 10.1.1. Profile summary
  • 10.2. Printing from a Poplar program
  • 10.3. Command line conversion
  • 10.4. Summary report format
• 11. Environment variables
  • 11.1. Logging
    • 11.1.1. Logging level
    • 11.1.2. Logging destination
  • 11.2. Profiling output
  • 11.3. Setting options
• 12. Application binary interface (ABI)
  • 12.1. Types
    • 12.1.1. Floating point types
    • 12.1.2. Structure types
    • 12.1.3. Bit fields
  • 12.2. Vertex calling convention
  • 12.3. Function calling convention
    • 12.3.1. Function parameters
    • 12.3.2. Return values
    • 12.3.3. Entry and exit
    • 12.3.4. Register assignments
  • 12.4. Stack frame
• 13. Legal notices