Chris Fallin 71ead6e31d x64 backend: implement 128-bit ops and misc fixes.
This implements all of the ops on I128 that are implemented by the
legacy x86 backend, and includes all that are required by at least one
major use-case (cg_clif rustc backend).

The sequences are open-coded where necessary; for e.g. the bit
operations, this can be somewhat complex, but these sequences have been
tested carefully. This PR also includes a drive-by fix of clz/ctz for 8-
and 16-bit cases where they were incorrect previously.

Also includes ridealong fixes developed while bringing up cg_clif
support, because they are difficult to completely separate due to
other refactors that occurred in this PR:

- fix REX prefix logic for some 8-bit instructions.

  When using an 8-bit register in 64-bit mode on x86-64, the REX prefix
  semantics are somewhat subtle: without the REX prefix, register numbers
  4--7 correspond to the second-to-lowest byte of the first four registers
  (AH, CH, BH, DH), whereas with the REX prefix, these register numbers
  correspond to the usual encoding (SPL, BPL, SIL, DIL). We could always
  emit a REX byte for instructions with 8-bit cases (this is harmless even
  if unneeded), but this would unnecessarily inflate code size; instead,
  the usual approach is to emit it only for these registers.

  This logic was present in some cases but missing for some other
  instructions: divide, not, negate, shifts.

  Fixes #2508.

- avoid unaligned SSE loads on some f64 ops.

  The implementations of several FP ops, such as fabs/fneg, used SSE
  instructions. This is not a problem per-se, except that load-op merging
  did not take *alignment* into account. Specifically, if an op on an f64
  loaded from memory happened to merge that load, and the instruction into
  which it was merged was an SSE instruction, then the SSE instruction
  imposes stricter (128-bit) alignment requirements than the load.f64 did.

  This PR simply forces any instruction lowerings that could use SSE
  instructions to implement non-SIMD operations to take inputs in
  registers only, and avoid load-op merging.

  Fixes #2507.

- two bugfixes exposed by cg_clif: urem/srem.i8, select.b1.

  - urem/srem.i8: the 8-bit form of the DIV instruction on x86-64 places
    the remainder in AH, not RDX, different from all the other width-forms
    of this instruction.

  - select.b1: we were not recognizing selects of boolean values as
    integer-typed operations, so we were generating XMM moves instead (!).
2021-01-14 13:45:50 -08:00
2021-01-04 14:50:42 -06:00
2020-12-14 13:39:38 -06:00
2020-02-28 09:16:05 -08:00
2021-01-04 09:05:42 -06:00

wasmtime

A standalone runtime for WebAssembly

A Bytecode Alliance project

build status zulip chat min rustc Documentation Status

Guide | Contributing | Website | Chat

Installation

The Wasmtime CLI can be installed on Linux and macOS with a small install script:

$ curl https://wasmtime.dev/install.sh -sSf | bash

Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.

Example

If you've got the Rust compiler installed then you can take some Rust source code:

fn main() {
    println!("Hello, world!");
}

and compile/run it with:

$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!

Features

  • Lightweight. Wasmtime is a standalone runtime for WebAssembly that scales with your needs. It fits on tiny chips as well as makes use of huge servers. Wasmtime can be embedded into almost any application too.

  • Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.

  • Configurable. Whether you need to precompile your wasm ahead of time, generate code blazingly fast with Lightbeam, or interpret it at runtime, Wasmtime has you covered for all your wasm-executing needs.

  • WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.

  • Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.

Language Support

You can use Wasmtime from a variety of different languages through embeddings of the implementation:

Documentation

📚 Read the Wasmtime guide here! 📚

The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!.


It's Wasmtime.

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Rust 77.8%
WebAssembly 20.6%
C 1.3%