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//! Runtime support needed for testing the stdarch crate.
//!
//! This basically just disassembles the current executable and then parses the
//! output once globally and then provides the `assert` function which makes
//! assertions about the disassembly of a function.
#![deny(rust_2018_idioms)]
#![allow(clippy::missing_docs_in_private_items, clippy::print_stdout)]
#[macro_use]
extern crate lazy_static;
#[macro_use]
extern crate cfg_if;
pub use assert_instr_macro::*;
pub use simd_test_macro::*;
use std::{cmp, collections::HashSet, env, hash, hint::black_box, str};
cfg_if! {
if #[cfg(target_arch = "wasm32")] {
pub mod wasm;
use wasm::disassemble_myself;
} else {
mod disassembly;
use crate::disassembly::disassemble_myself;
}
}
lazy_static! {
static ref DISASSEMBLY: HashSet<Function> = disassemble_myself();
}
#[derive(Debug)]
struct Function {
name: String,
instrs: Vec<String>,
}
impl Function {
fn new(n: &str) -> Self {
Self {
name: n.to_string(),
instrs: Vec::new(),
}
}
}
impl cmp::PartialEq for Function {
fn eq(&self, other: &Self) -> bool {
self.name == other.name
}
}
impl cmp::Eq for Function {}
impl hash::Hash for Function {
fn hash<H: hash::Hasher>(&self, state: &mut H) {
self.name.hash(state)
}
}
/// Main entry point for this crate, called by the `#[assert_instr]` macro.
///
/// This asserts that the function at `fnptr` contains the instruction
/// `expected` provided.
pub fn assert(shim_addr: usize, fnname: &str, expected: &str) {
// Make sure that the shim is not removed
black_box(shim_addr);
//eprintln!("shim name: {fnname}");
let function = &DISASSEMBLY
.get(&Function::new(fnname))
.unwrap_or_else(|| panic!("function \"{fnname}\" not found in the disassembly"));
//eprintln!(" function: {:?}", function);
let mut instrs = &function.instrs[..];
while instrs.last().map_or(false, |s| s == "nop") {
instrs = &instrs[..instrs.len() - 1];
}
// Look for `expected` as the first part of any instruction in this
// function, e.g., tzcntl in tzcntl %rax,%rax.
//
// There are two cases when the expected instruction is nop:
// 1. The expected intrinsic is compiled away so we can't
// check for it - aka the intrinsic is not generating any code.
// 2. It is a mark, indicating that the instruction will be
// compiled into other instructions - mainly because of llvm
// optimization.
let found = expected == "nop" || instrs.iter().any(|s| s.starts_with(expected));
// Look for subroutine call instructions in the disassembly to detect whether
// inlining failed: all intrinsics are `#[inline(always)]`, so calling one
// intrinsic from another should not generate subroutine call instructions.
let inlining_failed = if cfg!(target_arch = "x86_64") || cfg!(target_arch = "wasm32") {
instrs.iter().any(|s| s.starts_with("call "))
} else if cfg!(target_arch = "x86") {
instrs.windows(2).any(|s| {
// On 32-bit x86 position independent code will call itself and be
// immediately followed by a `pop` to learn about the current address.
// Let's not take that into account when considering whether a function
// failed inlining something.
s[0].starts_with("call ") && s[1].starts_with("pop") // FIXME: original logic but does not match comment
})
} else if cfg!(target_arch = "aarch64") {
instrs.iter().any(|s| s.starts_with("bl "))
} else {
// FIXME: Add detection for other archs
false
};
let instruction_limit = std::env::var("STDARCH_ASSERT_INSTR_LIMIT")
.ok()
.map_or_else(
|| match expected {
// `cpuid` returns a pretty big aggregate structure, so exempt
// it from the slightly more restrictive 22 instructions below.
"cpuid" => 30,
// Apparently, on Windows, LLVM generates a bunch of
// saves/restores of xmm registers around these intstructions,
// which exceeds the limit of 20 below. As it seems dictated by
// Windows's ABI (I believe?), we probably can't do much
// about it.
"vzeroall" | "vzeroupper" if cfg!(windows) => 30,
// Intrinsics using `cvtpi2ps` are typically "composites" and
// in some cases exceed the limit.
"cvtpi2ps" => 25,
// core_arch/src/arm_shared/simd32
// vfmaq_n_f32_vfma : #instructions = 26 >= 22 (limit)
"usad8" | "vfma" | "vfms" => 27,
"qadd8" | "qsub8" | "sadd8" | "sel" | "shadd8" | "shsub8" | "usub8" | "ssub8" => 29,
// core_arch/src/arm_shared/simd32
// vst1q_s64_x4_vst1 : #instructions = 22 >= 22 (limit)
"vld3" => 23,
// core_arch/src/arm_shared/simd32
// vld4q_lane_u32_vld4 : #instructions = 31 >= 22 (limit)
"vld4" => 32,
// core_arch/src/arm_shared/simd32
// vst1q_s64_x4_vst1 : #instructions = 40 >= 22 (limit)
"vst1" => 41,
// core_arch/src/arm_shared/simd32
// vst4q_u32_vst4 : #instructions = 26 >= 22 (limit)
"vst4" => 27,
// Temporary, currently the fptosi.sat and fptoui.sat LLVM
// intrinsics emit unnecessary code on arm. This can be
// removed once it has been addressed in LLVM.
"fcvtzu" | "fcvtzs" | "vcvt" => 64,
// core_arch/src/arm_shared/simd32
// vst1q_p64_x4_nop : #instructions = 33 >= 22 (limit)
"nop" if fnname.contains("vst1q_p64") => 34,
// Original limit was 20 instructions, but ARM DSP Intrinsics
// are exactly 20 instructions long. So, bump the limit to 22
// instead of adding here a long list of exceptions.
_ => 22,
},
|v| v.parse().unwrap(),
);
let probably_only_one_instruction = instrs.len() < instruction_limit;
if found && probably_only_one_instruction && !inlining_failed {
return;
}
// Help debug by printing out the found disassembly, and then panic as we
// didn't find the instruction.
println!("disassembly for {fnname}: ",);
for (i, instr) in instrs.iter().enumerate() {
println!("\t{i:2}: {instr}");
}
if !found {
panic!(
"failed to find instruction `{}` in the disassembly",
expected
);
} else if !probably_only_one_instruction {
panic!(
"instruction found, but the disassembly contains too many \
instructions: #instructions = {} >= {} (limit)",
instrs.len(),
instruction_limit
);
} else if inlining_failed {
panic!(
"instruction found, but the disassembly contains subroutine \
call instructions, which hint that inlining failed"
);
}
}
pub fn assert_skip_test_ok(name: &str) {
if env::var("STDARCH_TEST_EVERYTHING").is_err() {
return;
}
panic!("skipped test `{name}` when it shouldn't be skipped");
}
// See comment in `assert-instr-macro` crate for why this exists
pub static mut _DONT_DEDUP: *const u8 = std::ptr::null();
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