Software Pipelining Limitations

• Only innermost loop may be pipelined

• Any of the following inside a loop prevents software pipelining [Prog. Guide, Section 4.3.3]

  • Function calls (intrinsics are okay)
  • Conditional break (early exit)
  • Alteration of loop index (conditional or unconditional)
  • Requires more than 32 registers
  • Requires more than 5 conditional registers

• C intrinsics allow explicit access to special architectural features such as packed data types

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