library/stdarch/crates/stdarch-test/src/lib.rs

   1 //! Runtime support needed for testing the stdarch crate.
   2 //!
   3 //! This basically just disassembles the current executable and then parses the
   4 //! output once globally and then provides the `assert` function which makes
   5 //! assertions about the disassembly of a function.
   6 #![deny(rust_2018_idioms)]
   7 #![allow(clippy::missing_docs_in_private_items, clippy::print_stdout)]
   8
   9 #[macro_use]
  10 extern crate lazy_static;
  11 #[macro_use]
  12 extern crate cfg_if;
  13
  14 pub use assert_instr_macro::*;
  15 pub use simd_test_macro::*;
  16 use std::{cmp, collections::HashSet, env, hash, hint::black_box, str};
  17
  18 cfg_if! {
  19     if #[cfg(target_arch = "wasm32")] {
  20         pub mod wasm;
  21         use wasm::disassemble_myself;
  22     } else {
  23         mod disassembly;
  24         use crate::disassembly::disassemble_myself;
  25     }
  26 }
  27
  28 lazy_static! {
  29     static ref DISASSEMBLY: HashSet<Function> = disassemble_myself();
  30 }
  31
  32 #[derive(Debug)]
  33 struct Function {
  34     name: String,
  35     instrs: Vec<String>,
  36 }
  37 impl Function {
  38     fn new(n: &str) -> Self {
  39         Self {
  40             name: n.to_string(),
  41             instrs: Vec::new(),
  42         }
  43     }
  44 }
  45
  46 impl cmp::PartialEq for Function {
  47     fn eq(&self, other: &Self) -> bool {
  48         self.name == other.name
  49     }
  50 }
  51 impl cmp::Eq for Function {}
  52
  53 impl hash::Hash for Function {
  54     fn hash<H: hash::Hasher>(&self, state: &mut H) {
  55         self.name.hash(state)
  56     }
  57 }
  58
  59 /// Main entry point for this crate, called by the `#[assert_instr]` macro.
  60 ///
  61 /// This asserts that the function at `fnptr` contains the instruction
  62 /// `expected` provided.
  63 pub fn assert(shim_addr: usize, fnname: &str, expected: &str) {
  64     // Make sure that the shim is not removed
  65     black_box(shim_addr);
  66
  67     //eprintln!("shim name: {fnname}");
  68     let function = &DISASSEMBLY
  69         .get(&Function::new(fnname))
  70         .unwrap_or_else(|| panic!("function \"{fnname}\" not found in the disassembly"));
  71     //eprintln!("  function: {:?}", function);
  72
  73     let mut instrs = &function.instrs[..];
  74     while instrs.last().map_or(false, |s| s == "nop") {
  75         instrs = &instrs[..instrs.len() - 1];
  76     }
  77
  78     // Look for `expected` as the first part of any instruction in this
  79     // function, e.g., tzcntl in tzcntl %rax,%rax.
  80     //
  81     // There are two cases when the expected instruction is nop:
  82     // 1. The expected intrinsic is compiled away so we can't
  83     // check for it - aka the intrinsic is not generating any code.
  84     // 2. It is a mark, indicating that the instruction will be
  85     // compiled into other instructions - mainly because of llvm
  86     // optimization.
  87     let found = expected == "nop" || instrs.iter().any(|s| s.starts_with(expected));
  88
  89     // Look for subroutine call instructions in the disassembly to detect whether
  90     // inlining failed: all intrinsics are `#[inline(always)]`, so calling one
  91     // intrinsic from another should not generate subroutine call instructions.
  92     let inlining_failed = if cfg!(target_arch = "x86_64") || cfg!(target_arch = "wasm32") {
  93         instrs.iter().any(|s| s.starts_with("call "))
  94     } else if cfg!(target_arch = "x86") {
  95         instrs.windows(2).any(|s| {
  96             // On 32-bit x86 position independent code will call itself and be
  97             // immediately followed by a `pop` to learn about the current address.
  98             // Let's not take that into account when considering whether a function
  99             // failed inlining something.
 100             s[0].starts_with("call ") && s[1].starts_with("pop") // FIXME: original logic but does not match comment
 101         })
 102     } else if cfg!(target_arch = "aarch64") {
 103         instrs.iter().any(|s| s.starts_with("bl "))
 104     } else {
 105         // FIXME: Add detection for other archs
 106         false
 107     };
 108
 109     let instruction_limit = std::env::var("STDARCH_ASSERT_INSTR_LIMIT")
 110         .ok()
 111         .map_or_else(
 112             || match expected {
 113                 // `cpuid` returns a pretty big aggregate structure, so exempt
 114                 // it from the slightly more restrictive 22 instructions below.
 115                 "cpuid" => 30,
 116
 117                 // Apparently, on Windows, LLVM generates a bunch of
 118                 // saves/restores of xmm registers around these instructions,
 119                 // which exceeds the limit of 20 below. As it seems dictated by
 120                 // Windows's ABI (I believe?), we probably can't do much
 121                 // about it.
 122                 "vzeroall" | "vzeroupper" if cfg!(windows) => 30,
 123
 124                 // Intrinsics using `cvtpi2ps` are typically "composites" and
 125                 // in some cases exceed the limit.
 126                 "cvtpi2ps" => 25,
 127                 // core_arch/src/arm_shared/simd32
 128                 // vfmaq_n_f32_vfma : #instructions = 26 >= 22 (limit)
 129                 "usad8" | "vfma" | "vfms" => 27,
 130                 "qadd8" | "qsub8" | "sadd8" | "sel" | "shadd8" | "shsub8" | "usub8" | "ssub8" => 29,
 131                 // core_arch/src/arm_shared/simd32
 132                 // vst1q_s64_x4_vst1 : #instructions = 22 >= 22 (limit)
 133                 "vld3" => 23,
 134                 // core_arch/src/arm_shared/simd32
 135                 // vld4q_lane_u32_vld4 : #instructions = 31 >= 22 (limit)
 136                 "vld4" => 32,
 137                 // core_arch/src/arm_shared/simd32
 138                 // vst1q_s64_x4_vst1 : #instructions = 40 >= 22 (limit)
 139                 "vst1" => 41,
 140                 // core_arch/src/arm_shared/simd32
 141                 // vst4q_u32_vst4 : #instructions = 26 >= 22 (limit)
 142                 "vst4" => 27,
 143
 144                 // Temporary, currently the fptosi.sat and fptoui.sat LLVM
 145                 // intrinsics emit unnecessary code on arm. This can be
 146                 // removed once it has been addressed in LLVM.
 147                 "fcvtzu" | "fcvtzs" | "vcvt" => 64,
 148
 149                 // core_arch/src/arm_shared/simd32
 150                 // vst1q_p64_x4_nop : #instructions = 33 >= 22 (limit)
 151                 "nop" if fnname.contains("vst1q_p64") => 34,
 152
 153                 // Original limit was 20 instructions, but ARM DSP Intrinsics
 154                 // are exactly 20 instructions long. So, bump the limit to 22
 155                 // instead of adding here a long list of exceptions.
 156                 _ => 22,
 157             },
 158             |v| v.parse().unwrap(),
 159         );
 160     let probably_only_one_instruction = instrs.len() < instruction_limit;
 161
 162     if found && probably_only_one_instruction && !inlining_failed {
 163         return;
 164     }
 165
 166     // Help debug by printing out the found disassembly, and then panic as we
 167     // didn't find the instruction.
 168     println!("disassembly for {fnname}: ",);
 169     for (i, instr) in instrs.iter().enumerate() {
 170         println!("\t{i:2}: {instr}");
 171     }
 172
 173     if !found {
 174         panic!(
 175             "failed to find instruction `{}` in the disassembly",
 176             expected
 177         );
 178     } else if !probably_only_one_instruction {
 179         panic!(
 180             "instruction found, but the disassembly contains too many \
 181              instructions: #instructions = {} >= {} (limit)",
 182             instrs.len(),
 183             instruction_limit
 184         );
 185     } else if inlining_failed {
 186         panic!(
 187             "instruction found, but the disassembly contains subroutine \
 188              call instructions, which hint that inlining failed"
 189         );
 190     }
 191 }
 192
 193 pub fn assert_skip_test_ok(name: &str) {
 194     if env::var("STDARCH_TEST_EVERYTHING").is_err() {
 195         return;
 196     }
 197     panic!("skipped test `{name}` when it shouldn't be skipped");
 198 }
 199
 200 // See comment in `assert-instr-macro` crate for why this exists
 201 pub static mut _DONT_DEDUP: *const u8 = std::ptr::null();