课程笔记：CHI Hierarchical Instructions | Taichi

本文是 Taichi 官方教学视频的笔记：

Chi Hierarchical Instructions

Overview

“CHI” 含义是「气」。

Why CHI?

• Portability
• High performance
• Taichi features
  • Sparse programming
  • Differentiable programming
  • Quantization
  • ……

Statements

• 50 statements (compared to 70 statements in Taichi codebase)
• Arithmetic: [Unary/Binary/Ternary/Atomic]OpStmt
• Memory access: [Local/Global][Load/Store/Ptr]Stmt
• Control flows: [If/RangeFor/StructFor/While/Continue/…]Stmt
• Autodiff stack operations: AdStack[Alloca/LoadTop/Pop/…]Stmt
• SNode operations: SNode[Lookup/Op]Stmt, Get[Root/Ch]Stmt
• Compiler hints: RangeAssumptionStmt, LoopUniqueStmt
• Others: PrintStmt, RandStmt, ConstStmt, AssertStmt

IR Builder

• An interface to generate CHI IR conveniently
• Example: generate 40 + 2:

Loop guards

• Handle insertion points automatically
• WYSIWYG

Interaction with C++ arrays

Key compilation passes

• Type checking
• (Optional) Automatic Differentiation
• Automatic Parallelization (Offload)
• Lower access
• (And many optimization passes)

Pass manager？

如果想添加自定义 compilation pass，要不要写 pass manager，直接还是用 function interface，而不是像 LLVM/TVM/SPIR-V 这种用 pass class 来 pass class。

Typical API for now:

bool my_foo_pass(IRNode *ir,
                 const CompileConfig &config,
                 AnalysisManager *amgr,
                 const MyFooPass::Args &args);