PTO Virtual Instruction Set Architecture Manual¶

0.1 Scope¶

This manual defines the architecture-level contract of the PTO Virtual Instruction Set Architecture (VISA). It specifies what a conforming frontend, IR pipeline, backend, and runtime MUST preserve when executing PTO programs.

Per-instruction pages in docs/isa/*.md remain the canonical source for opcode-specific semantics. This manual defines the system-level contract around those semantics.

0.2 Audience¶

This manual is intended for:

compiler and IR engineers implementing PTO lowering pipelines
backend engineers implementing target legalization and code generation
kernel authors validating architecture-visible behavior
simulator and conformance-test developers

0.3 Document conventions¶

This manual uses a PTX/Tile-IR-inspired structure while preserving PTO-specific architecture design. Each chapter follows a normative pattern where applicable:

scope
syntax/form
semantics
constraints
diagnostics
compatibility

0.4 Conformance language¶

The key words MUST, MUST NOT, SHOULD, and MAY are normative.

MUST / MUST NOT: mandatory architectural requirement.
SHOULD: recommended requirement; deviations require explicit rationale.
MAY: optional behavior explicitly allowed by the architecture.

0.5 Authority order¶

When documents differ, resolve in this order:

docs/isa/*.md for per-instruction semantics and constraints.
include/pto/common/pto_instr.hpp for public API surface and overload shape.
This manual for architecture layering, contracts, and conformance policy.