Qualcomm Hexagon DSP User Guide 80 VB419 108

• 1 Introduction
  • 1.1 Purpose
  • 1.2 Conventions
  • 1.3 Technical assistance
• 2 Architecture overview
  • 2.1 Qualcomm® Snapdragon™ processors
  • 2.2 cDSP
    • 2.2.1 Hexagon scalar unit
    • 2.2.2 Hexagon HVX unit
  • 2.3 Memory subsystem
  • 2.4 Development boards
• 3 Run tasks on the DSP threads
  • 3.1 When to offload tasks onto the DSP
  • 3.2 Offload tasks from the CPU onto a DSP thread
    • 3.2.1 FastRPC fundamentals
    • 3.2.2 Multi-domain support
    • 3.2.3 Run the main function on Hexagon DSP
  • 3.3 Offload tasks from one DSP thread to another
  • 3.4 Optimize multi-threaded DSP code
    • 3.4.1 Compile-time multithreading
    • 3.4.2 Run-time multithreading
  • 3.5 Verify an application running on the DSP
  • 3.6 Overhead for a FastRPC call
  • 3.7 Overhead for launching DSP threads from the DSP
• 4 Optimize tasks for the DSP
  • 4.1 Programming languages and extensions
    • 4.1.1 C/C++ support
    • 4.1.2 Halide language
    • 4.1.3 Compiler intrinsics
    • 4.1.4 Assembly language
  • 4.2 Guidelines for assembly and intrinsic optimization
    • 4.2.1 Maximize instructions per packet
      • 4.2.1.1 Scalar instruction packing rules
      • 4.2.1.2 HVX packing rules
    • 4.2.2 Understand and reduce stalls
      • 4.2.2.1 Instruction latencies
        • 4.2.2.1.1 Thread vs. processor cycles
        • 4.2.2.1.2 Scalar latencies
        • 4.2.2.1.3 HVX latencies
      • 4.2.2.2 Resource contention on the shared scalar resources
      • 4.2.2.3 Understand and optimize memory accesses
    • 4.2.3 Software pipelining
  • 4.3 HVX-specific optimizations
    • 4.3.1 When to use HVX
    • 4.3.2 64-byte mode deprecation
    • 4.3.3 Rearrange elements within HVX vectors
    • 4.3.4 VTCM/lookup
    • 4.3.5 Emulate floating-point
    • 4.3.6 Convert float to fix
• 5 Debugging
  • 5.1 Common issues
  • 5.2 Debugging with the tools
    • 5.2.1 qprintf
    • 5.2.2 Build targets
    • 5.2.3 Disassemble code
    • 5.2.4 Use the debugger
• 6 Profiling
  • 6.1 Read timers
    • 6.1.1 Measure time
    • 6.1.2 Measure processor cycles
  • 6.2 Profile on the simulator
    • 6.2.1 High-level profiling
    • 6.2.2 Low-level profiling
  • 6.3 Profile on target with the Hexagon Trace Analyzer
  • 6.4 Profile on target with the Android Hexagon profiler