#targets

Targets Summary

§1 Status legend must-have : Phase 1 ships this combination. Mochi without it is not a credible product. should-have : Phase 1 or early Phase 2. A serious gap if missing. could-have : Phase 2 or later. Valuable to advanced users, not blocking. out-of-scope : not planned for any phase of MEP-42 (might be MEP-43+ or never). Engineering complexity is a rough 1 to 5 ordinal: 1 = a week...

WebAssembly

§1 Provenance WebAssembly Core Specification 3.0: https://webassembly.github.io/spec/core/ (W3C release September 2025). Wasm 3.0 release announcement: https://webassembly.org/news/2025-09-17-wasm-3.0/ . Feature status tracker: https://webassembly.org/features/ . Component Model spec: https://github.com/WebAssembly/component-model . WASI roadmap: https://wasi.dev/roadmap . WASI Preview 2 standard: https://github.com/WebAssembly/WASI/tree/main/wasip2 . Wasmtime documentation: https://docs.wasmtime.dev/ . WAMR (WebAssembly Micro Runtime): https://github.com/bytecodealliance/wasm-micro-runtime . §2 Mechanism / specification Wasm is a stack-based virtual ISA with structured control flow (no arbitrary jumps; blocks, loops, ifs, branches). The binary...

Other ISAs: PowerPC, MIPS, LoongArch, s390x, Apple GPU/Metal

§1 Provenance Power ISA v3.1 (and later) specification: https://openpowerfoundation.org/specifications/isa/ . 64-bit ELFv2 ABI Specification (ppc64le): https://openpowerfoundation.org/specifications/64bitelfv2abi/ . MIPS Architecture for Programmers documentation: https://www.mips.com/products/architectures/ (Imagination's MIPS pages; the canonical spec PDFs). LoongArch ELF psABI: https://github.com/loongson/la-abi-specs . LoongArch architecture reference: https://loongson.github.io/LoongArch-Documentation/ . z/Architecture Principles of Operation (IBM): https://www.ibm.com/support/pages/zarchitecture-principles-operation-spreadsheet (search for SA22-7832). ELF ABI for s390x: https://github.com/IBM/s390x-abi . Metal Shading Language specification (Apple): https://developer.apple.com/metal/Metal-Shading-Language-Specification.pdf . §2 PowerPC / POWER POWER10 launched in 2021...

RISC-V RV64GC

§1 Provenance RISC-V Unprivileged ISA Manual: https://github.com/riscv/riscv-isa-manual (the canonical Volume I). RISC-V Privileged ISA Manual: same repo, Volume II. RISC-V psABI (ELF): https://github.com/riscv-non-isa/riscv-elf-psabi-doc . RISC-V Vector ISA (V 1.0): https://github.com/riscv/riscv-v-spec . RISC-V Profiles (RVA20, RVA22, RVA23): https://github.com/riscv/riscv-profiles . RISC-V Ratified Extensions list: https://riscv.atlassian.net/wiki/spaces/HOME/pages/16154732/Ratified+Extensions . Linux kernel arch/riscv documentation: https://docs.kernel.org/arch/riscv/ . §2 Mechanism / specification RV64GC = RV64I (base 64-bit integer) + M (multiply/divide) + A (atomics) + F (single-precision FP)...

AArch64 Windows (Windows-on-ARM64)

§1 Provenance Microsoft ARM64 calling convention: https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions . ARM64EC ABI: https://learn.microsoft.com/en-us/windows/arm/arm64ec-abi . Windows on ARM developer docs: https://learn.microsoft.com/en-us/windows/arm/ . PE/COFF spec: https://learn.microsoft.com/en-us/windows/win32/debug/pe-format (the IMAGE_FILE_MACHINE_ARM64 magic value is 0xAA64; ARM64EC is 0xA641). AAPCS64 base spec (Microsoft's ARM64 is a delta off this): https://github.com/ARM-software/abi-aa . Snapdragon X Elite developer kit reference: https://www.qualcomm.com/products/internet-of-things/development/snapdragon-developer-kits/snapdragon-dev-kit-for-windows . §2 Mechanism / specification The Microsoft ARM64 ABI is based on AAPCS64 with these deltas: Variadic functions: all floats...

x86_64 Windows (Microsoft x64) ABI

§1 Provenance Microsoft x64 calling convention reference: https://learn.microsoft.com/en-us/cpp/build/x64-calling-convention . x64 stack usage and prolog/epilog: https://learn.microsoft.com/en-us/cpp/build/stack-usage and https://learn.microsoft.com/en-us/cpp/build/prolog-and-epilog . x64 exception handling: https://learn.microsoft.com/en-us/cpp/build/exception-handling-x64 . PE/COFF spec (the file-format counterpart): https://learn.microsoft.com/en-us/windows/win32/debug/pe-format . Intel SDM and AMD64 Programmer's Manual (same as SysV). PDB / CodeView reference: Microsoft's docs are partial; the de-facto reference is the LLVM llvm-pdbutil and microsoft-pdb GitHub repo at https://github.com/microsoft/microsoft-pdb . §2 Mechanism / specification Integer/pointer arguments: RCX, RDX, R8,...

AArch64 AAPCS64

§1 Provenance AAPCS64 canonical text: https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst (and the published PDF at https://developer.arm.com/documentation/ihi0055/latest/) . ARM Architecture Reference Manual for A-profile (Arm ARM): https://developer.arm.com/documentation/ddi0487/latest/ . ELF for the Arm 64-bit architecture (AAELF64): https://github.com/ARM-software/abi-aa/blob/main/aaelf64/aaelf64.rst . Apple ARM64 documented deviations: https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms . Microsoft ARM64 calling convention: https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions . Apple ARM64e (PAC) overview: https://developer.apple.com/documentation/security/preparing-your-app-to-work-with-pointer-authentication . §2 Mechanism / specification Integer/pointer arguments: X0 to X7. Floating-point/SIMD arguments: V0 to V7 (V is the 128-bit vector view;...

x86_64 System V AMD64 ABI

§1 Provenance Canonical specifications: Official psABI (community maintained): https://gitlab.com/x86-psABIs/x86-64-ABI (the LaTeX source and PDF builds live here, currently revision 1.0+, with continuous incremental amendments tracked in git). Historical baseline PDF (v0.99): https://refspecs.linuxbase.org/elf/x86_64-abi-0.99.pdf . Intel 64 and IA-32 Architectures Software Developer's Manual (Intel SDM), Volumes 1, 2, 3, 4: https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html . AMD64 Architecture Programmer's Manual, Vols 1 to 5: https://www.amd.com/en/search/documentation/hub.html?keyword=AMD64+Architecture+Programmer%27s+Manual . Intel APX Architecture Specification: https://cdrdv2-public.intel.com/784266/355828-intel-apx-spec.pdf (revised through 2025). Apple's notes...

Target ISAs and ABIs