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Rename SimpleJIT to JIT as it isn't simple anymore

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bjorn3
2020-12-04 19:28:31 +01:00
committed by Andrew Brown
parent 502b39606f
commit 411ec3a857
16 changed files with 68 additions and 74 deletions
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[package]
name = "cranelift-jit"
version = "0.68.0"
authors = ["The Cranelift Project Developers"]
description = "A JIT library backed by Cranelift"
repository = "https://github.com/bytecodealliance/wasmtime"
documentation = "https://docs.rs/cranelift-jit"
license = "Apache-2.0 WITH LLVM-exception"
readme = "README.md"
edition = "2018"
[dependencies]
cranelift-module = { path = "../module", version = "0.68.0" }
cranelift-native = { path = "../native", version = "0.68.0" }
cranelift-codegen = { path = "../codegen", version = "0.68.0", default-features = false, features = ["std"] }
cranelift-entity = { path = "../entity", version = "0.68.0" }
anyhow = "1.0"
region = "2.2.0"
libc = { version = "0.2.42" }
errno = "0.2.4"
target-lexicon = "0.11"
memmap = { version = "0.7.0", optional = true }
log = { version = "0.4.6", default-features = false }
[target.'cfg(target_os = "windows")'.dependencies]
winapi = { version = "0.3", features = ["winbase", "memoryapi"] }
[features]
selinux-fix = ['memmap']
default = []
[dev-dependencies]
cranelift = { path = "../umbrella", version = "0.68.0" }
cranelift-frontend = { path = "../frontend", version = "0.68.0" }
cranelift-entity = { path = "../entity", version = "0.68.0" }
[badges]
maintenance = { status = "experimental" }

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This crate provides a JIT library that uses
[Cranelift](https://crates.io/crates/cranelift).
This crate is extremely experimental.
See the [example program] for a brief overview of how to use this.
[example program]: https://github.com/bytecodealliance/wasmtime/blob/main/cranelift/jit/examples/jit-minimal.rs

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use cranelift::prelude::*;
use cranelift_codegen::binemit::NullTrapSink;
use cranelift_codegen::settings::{self, Configurable};
use cranelift_jit::{JITBuilder, JITModule};
use cranelift_module::{default_libcall_names, Linkage, Module};
use std::mem;
fn main() {
let mut flag_builder = settings::builder();
flag_builder.set("use_colocated_libcalls", "false").unwrap();
// FIXME set back to true once the x64 backend supports it.
flag_builder.set("is_pic", "false").unwrap();
let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
panic!("host machine is not supported: {}", msg);
});
let isa = isa_builder.finish(settings::Flags::new(flag_builder));
let mut module = JITModule::new(JITBuilder::with_isa(isa, default_libcall_names()));
let mut ctx = module.make_context();
let mut func_ctx = FunctionBuilderContext::new();
let mut sig_a = module.make_signature();
sig_a.params.push(AbiParam::new(types::I32));
sig_a.returns.push(AbiParam::new(types::I32));
let mut sig_b = module.make_signature();
sig_b.returns.push(AbiParam::new(types::I32));
let func_a = module
.declare_function("a", Linkage::Local, &sig_a)
.unwrap();
let func_b = module
.declare_function("b", Linkage::Local, &sig_b)
.unwrap();
ctx.func.signature = sig_a;
ctx.func.name = ExternalName::user(0, func_a.as_u32());
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
bcx.append_block_params_for_function_params(block);
let param = bcx.block_params(block)[0];
let cst = bcx.ins().iconst(types::I32, 37);
let add = bcx.ins().iadd(cst, param);
bcx.ins().return_(&[add]);
bcx.seal_all_blocks();
bcx.finalize();
}
let mut trap_sink = NullTrapSink {};
module
.define_function(func_a, &mut ctx, &mut trap_sink)
.unwrap();
module.clear_context(&mut ctx);
ctx.func.signature = sig_b;
ctx.func.name = ExternalName::user(0, func_b.as_u32());
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
let local_func = module.declare_func_in_func(func_a, &mut bcx.func);
let arg = bcx.ins().iconst(types::I32, 5);
let call = bcx.ins().call(local_func, &[arg]);
let value = {
let results = bcx.inst_results(call);
assert_eq!(results.len(), 1);
results[0].clone()
};
bcx.ins().return_(&[value]);
bcx.seal_all_blocks();
bcx.finalize();
}
module
.define_function(func_b, &mut ctx, &mut trap_sink)
.unwrap();
module.clear_context(&mut ctx);
// Perform linking.
module.finalize_definitions();
// Get a raw pointer to the generated code.
let code_b = module.get_finalized_function(func_b);
// Cast it to a rust function pointer type.
let ptr_b = unsafe { mem::transmute::<_, fn() -> u32>(code_b) };
// Call it!
let res = ptr_b();
assert_eq!(res, 42);
}

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//! Defines `JITModule`.
use crate::{compiled_blob::CompiledBlob, memory::Memory};
use cranelift_codegen::isa::TargetIsa;
use cranelift_codegen::settings::Configurable;
use cranelift_codegen::{self, ir, settings};
use cranelift_codegen::{
binemit::{self, Addend, CodeInfo, CodeOffset, Reloc, RelocSink, TrapSink},
CodegenError,
};
use cranelift_entity::SecondaryMap;
use cranelift_module::{
DataContext, DataDescription, DataId, FuncId, Init, Linkage, Module, ModuleCompiledFunction,
ModuleDeclarations, ModuleError, ModuleResult, RelocRecord,
};
use cranelift_native;
#[cfg(not(windows))]
use libc;
use log::info;
use std::collections::HashMap;
use std::convert::{TryFrom, TryInto};
use std::ffi::CString;
use std::io::Write;
use std::ptr;
use std::ptr::NonNull;
use target_lexicon::PointerWidth;
#[cfg(windows)]
use winapi;
const EXECUTABLE_DATA_ALIGNMENT: u64 = 0x10;
const WRITABLE_DATA_ALIGNMENT: u64 = 0x8;
const READONLY_DATA_ALIGNMENT: u64 = 0x1;
/// A builder for `JITModule`.
pub struct JITBuilder {
isa: Box<dyn TargetIsa>,
symbols: HashMap<String, *const u8>,
libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>,
hotswap_enabled: bool,
}
impl JITBuilder {
/// Create a new `JITBuilder`.
///
/// The `libcall_names` function provides a way to translate `cranelift_codegen`'s `ir::LibCall`
/// enum to symbols. LibCalls are inserted in the IR as part of the legalization for certain
/// floating point instructions, and for stack probes. If you don't know what to use for this
/// argument, use `cranelift_module::default_libcall_names()`.
pub fn new(libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>) -> Self {
let mut flag_builder = settings::builder();
// On at least AArch64, "colocated" calls use shorter-range relocations,
// which might not reach all definitions; we can't handle that here, so
// we require long-range relocation types.
flag_builder.set("use_colocated_libcalls", "false").unwrap();
flag_builder.set("is_pic", "true").unwrap();
let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
panic!("host machine is not supported: {}", msg);
});
let isa = isa_builder.finish(settings::Flags::new(flag_builder));
Self::with_isa(isa, libcall_names)
}
/// Create a new `JITBuilder` with an arbitrary target. This is mainly
/// useful for testing.
///
/// To create a `JITBuilder` for native use, use the `new` constructor
/// instead.
///
/// The `libcall_names` function provides a way to translate `cranelift_codegen`'s `ir::LibCall`
/// enum to symbols. LibCalls are inserted in the IR as part of the legalization for certain
/// floating point instructions, and for stack probes. If you don't know what to use for this
/// argument, use `cranelift_module::default_libcall_names()`.
pub fn with_isa(
isa: Box<dyn TargetIsa>,
libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>,
) -> Self {
let symbols = HashMap::new();
Self {
isa,
symbols,
libcall_names,
hotswap_enabled: false,
}
}
/// Define a symbol in the internal symbol table.
///
/// The JIT will use the symbol table to resolve names that are declared,
/// but not defined, in the module being compiled. A common example is
/// external functions. With this method, functions and data can be exposed
/// to the code being compiled which are defined by the host.
///
/// If a symbol is defined more than once, the most recent definition will
/// be retained.
///
/// If the JIT fails to find a symbol in its internal table, it will fall
/// back to a platform-specific search (this typically involves searching
/// the current process for public symbols, followed by searching the
/// platform's C runtime).
pub fn symbol<K>(&mut self, name: K, ptr: *const u8) -> &Self
where
K: Into<String>,
{
self.symbols.insert(name.into(), ptr);
self
}
/// Define multiple symbols in the internal symbol table.
///
/// Using this is equivalent to calling `symbol` on each element.
pub fn symbols<It, K>(&mut self, symbols: It) -> &Self
where
It: IntoIterator<Item = (K, *const u8)>,
K: Into<String>,
{
for (name, ptr) in symbols {
self.symbols.insert(name.into(), ptr);
}
self
}
/// Enable or disable hotswap support. See [`JITModule::prepare_for_function_redefine`]
/// for more information.
///
/// Enabling hotswap support requires PIC code.
pub fn hotswap(&mut self, enabled: bool) -> &mut Self {
self.hotswap_enabled = enabled;
self
}
}
/// A `JITModule` implements `Module` and emits code and data into memory where it can be
/// directly called and accessed.
///
/// See the `JITBuilder` for a convenient way to construct `JITModule` instances.
pub struct JITModule {
isa: Box<dyn TargetIsa>,
hotswap_enabled: bool,
symbols: HashMap<String, *const u8>,
libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
memory: MemoryHandle,
declarations: ModuleDeclarations,
function_got_entries: SecondaryMap<FuncId, Option<NonNull<*const u8>>>,
function_plt_entries: SecondaryMap<FuncId, Option<NonNull<[u8; 16]>>>,
data_object_got_entries: SecondaryMap<DataId, Option<NonNull<*const u8>>>,
libcall_got_entries: HashMap<ir::LibCall, NonNull<*const u8>>,
libcall_plt_entries: HashMap<ir::LibCall, NonNull<[u8; 16]>>,
compiled_functions: SecondaryMap<FuncId, Option<CompiledBlob>>,
compiled_data_objects: SecondaryMap<DataId, Option<CompiledBlob>>,
functions_to_finalize: Vec<FuncId>,
data_objects_to_finalize: Vec<DataId>,
}
/// A handle to allow freeing memory allocated by the `Module`.
struct MemoryHandle {
code: Memory,
readonly: Memory,
writable: Memory,
}
impl JITModule {
/// Free memory allocated for code and data segments of compiled functions.
///
/// # Safety
///
/// Because this function invalidates any pointers retrived from the
/// corresponding module, it should only be used when none of the functions
/// from that module are currently executing and none of the `fn` pointers
/// are called afterwards.
pub unsafe fn free_memory(&mut self) {
self.memory.code.free_memory();
self.memory.readonly.free_memory();
self.memory.writable.free_memory();
}
fn lookup_symbol(&self, name: &str) -> Option<*const u8> {
self.symbols
.get(name)
.copied()
.or_else(|| lookup_with_dlsym(name))
}
unsafe fn write_plt_entry_bytes(plt_ptr: *mut [u8; 16], got_ptr: *mut *const u8) {
assert!(
cfg!(target_arch = "x86_64"),
"PLT is currently only supported on x86_64"
);
// jmp *got_ptr; ud2; ud2; ud2; ud2; ud2
let mut plt_val = [
0xff, 0x25, 0, 0, 0, 0, 0x0f, 0x0b, 0x0f, 0x0b, 0x0f, 0x0b, 0x0f, 0x0b, 0x0f, 0x0b,
];
let what = got_ptr as isize - 4;
let at = plt_ptr as isize + 2;
plt_val[2..6].copy_from_slice(&i32::to_ne_bytes(i32::try_from(what - at).unwrap()));
std::ptr::write(plt_ptr, plt_val);
}
fn get_address(&self, name: &ir::ExternalName) -> *const u8 {
match *name {
ir::ExternalName::User { .. } => {
let (name, linkage) = if ModuleDeclarations::is_function(name) {
if self.hotswap_enabled {
return self.get_plt_address(name);
} else {
let func_id = FuncId::from_name(name);
match &self.compiled_functions[func_id] {
Some(compiled) => return compiled.ptr,
None => {
let decl = self.declarations.get_function_decl(func_id);
(&decl.name, decl.linkage)
}
}
}
} else {
let data_id = DataId::from_name(name);
match &self.compiled_data_objects[data_id] {
Some(compiled) => return compiled.ptr,
None => {
let decl = self.declarations.get_data_decl(data_id);
(&decl.name, decl.linkage)
}
}
};
if let Some(ptr) = self.lookup_symbol(&name) {
ptr
} else if linkage == Linkage::Preemptible {
0 as *const u8
} else {
panic!("can't resolve symbol {}", name);
}
}
ir::ExternalName::LibCall(ref libcall) => {
let sym = (self.libcall_names)(*libcall);
self.lookup_symbol(&sym)
.unwrap_or_else(|| panic!("can't resolve libcall {}", sym))
}
_ => panic!("invalid ExternalName {}", name),
}
}
fn get_got_address(&self, name: &ir::ExternalName) -> *const u8 {
match *name {
ir::ExternalName::User { .. } => {
if ModuleDeclarations::is_function(name) {
let func_id = FuncId::from_name(name);
self.function_got_entries[func_id]
.unwrap()
.as_ptr()
.cast::<u8>()
} else {
let data_id = DataId::from_name(name);
self.data_object_got_entries[data_id]
.unwrap()
.as_ptr()
.cast::<u8>()
}
}
ir::ExternalName::LibCall(ref libcall) => self
.libcall_got_entries
.get(libcall)
.unwrap_or_else(|| panic!("can't resolve libcall {}", libcall))
.as_ptr()
.cast::<u8>(),
_ => panic!("invalid ExternalName {}", name),
}
}
fn get_plt_address(&self, name: &ir::ExternalName) -> *const u8 {
match *name {
ir::ExternalName::User { .. } => {
if ModuleDeclarations::is_function(name) {
let func_id = FuncId::from_name(name);
self.function_plt_entries[func_id]
.unwrap()
.as_ptr()
.cast::<u8>()
} else {
unreachable!("PLT relocations can only have functions as target");
}
}
ir::ExternalName::LibCall(ref libcall) => self
.libcall_plt_entries
.get(libcall)
.unwrap_or_else(|| panic!("can't resolve libcall {}", libcall))
.as_ptr()
.cast::<u8>(),
_ => panic!("invalid ExternalName {}", name),
}
}
/// Returns the address of a finalized function.
pub fn get_finalized_function(&self, func_id: FuncId) -> *const u8 {
let info = &self.compiled_functions[func_id];
assert!(
!self.functions_to_finalize.iter().any(|x| *x == func_id),
"function not yet finalized"
);
info.as_ref()
.expect("function must be compiled before it can be finalized")
.ptr
}
/// Returns the address and size of a finalized data object.
pub fn get_finalized_data(&self, data_id: DataId) -> (*const u8, usize) {
let info = &self.compiled_data_objects[data_id];
assert!(
!self.data_objects_to_finalize.iter().any(|x| *x == data_id),
"data object not yet finalized"
);
let compiled = info
.as_ref()
.expect("data object must be compiled before it can be finalized");
(compiled.ptr, compiled.size)
}
fn record_function_for_perf(&self, ptr: *mut u8, size: usize, name: &str) {
// The Linux perf tool supports JIT code via a /tmp/perf-$PID.map file,
// which contains memory regions and their associated names. If we
// are profiling with perf and saving binaries to PERF_BUILDID_DIR
// for post-profile analysis, write information about each function
// we define.
if cfg!(target_os = "linux") && ::std::env::var_os("PERF_BUILDID_DIR").is_some() {
let mut map_file = ::std::fs::OpenOptions::new()
.create(true)
.append(true)
.open(format!("/tmp/perf-{}.map", ::std::process::id()))
.unwrap();
let _ = writeln!(map_file, "{:x} {:x} {}", ptr as usize, size, name);
}
}
/// Finalize all functions and data objects that are defined but not yet finalized.
/// All symbols referenced in their bodies that are declared as needing a definition
/// must be defined by this point.
///
/// Use `get_finalized_function` and `get_finalized_data` to obtain the final
/// artifacts.
pub fn finalize_definitions(&mut self) {
for func in std::mem::take(&mut self.functions_to_finalize) {
let decl = self.declarations.get_function_decl(func);
assert!(decl.linkage.is_definable());
let func = self.compiled_functions[func]
.as_ref()
.expect("function must be compiled before it can be finalized");
func.perform_relocations(
|name| self.get_address(name),
|name| self.get_got_address(name),
|name| self.get_plt_address(name),
);
}
for data in std::mem::take(&mut self.data_objects_to_finalize) {
let decl = self.declarations.get_data_decl(data);
assert!(decl.linkage.is_definable());
let data = self.compiled_data_objects[data]
.as_ref()
.expect("data object must be compiled before it can be finalized");
data.perform_relocations(
|name| self.get_address(name),
|name| self.get_got_address(name),
|name| self.get_plt_address(name),
);
}
// Now that we're done patching, prepare the memory for execution!
self.memory.readonly.set_readonly();
self.memory.code.set_readable_and_executable();
}
/// Create a new `JITModule`.
pub fn new(builder: JITBuilder) -> Self {
if builder.hotswap_enabled {
assert!(
builder.isa.flags().is_pic(),
"Hotswapping requires PIC code"
);
}
let mut memory = MemoryHandle {
code: Memory::new(),
readonly: Memory::new(),
writable: Memory::new(),
};
let mut libcall_got_entries = HashMap::new();
let mut libcall_plt_entries = HashMap::new();
// Pre-create a GOT and PLT entry for each libcall.
let all_libcalls = if builder.isa.flags().is_pic() {
ir::LibCall::all_libcalls()
} else {
&[] // Not PIC, so no GOT and PLT entries necessary
};
for &libcall in all_libcalls {
let got_entry = memory
.writable
.allocate(
std::mem::size_of::<*const u8>(),
std::mem::align_of::<*const u8>().try_into().unwrap(),
)
.unwrap()
.cast::<*const u8>();
libcall_got_entries.insert(libcall, NonNull::new(got_entry).unwrap());
let sym = (builder.libcall_names)(libcall);
let addr = if let Some(addr) = builder
.symbols
.get(&sym)
.copied()
.or_else(|| lookup_with_dlsym(&sym))
{
addr
} else {
continue;
};
unsafe {
std::ptr::write(got_entry, addr);
}
let plt_entry = memory
.code
.allocate(std::mem::size_of::<[u8; 16]>(), EXECUTABLE_DATA_ALIGNMENT)
.unwrap()
.cast::<[u8; 16]>();
libcall_plt_entries.insert(libcall, NonNull::new(plt_entry).unwrap());
unsafe {
Self::write_plt_entry_bytes(plt_entry, got_entry);
}
}
Self {
isa: builder.isa,
hotswap_enabled: builder.hotswap_enabled,
symbols: builder.symbols,
libcall_names: builder.libcall_names,
memory,
declarations: ModuleDeclarations::default(),
function_got_entries: SecondaryMap::new(),
function_plt_entries: SecondaryMap::new(),
data_object_got_entries: SecondaryMap::new(),
libcall_got_entries,
libcall_plt_entries,
compiled_functions: SecondaryMap::new(),
compiled_data_objects: SecondaryMap::new(),
functions_to_finalize: Vec::new(),
data_objects_to_finalize: Vec::new(),
}
}
/// Allow a single future `define_function` on a previously defined function. This allows for
/// hot code swapping and lazy compilation of functions.
///
/// This requires hotswap support to be enabled first using [`JITBuilder::hotswap`].
pub fn prepare_for_function_redefine(&mut self, func_id: FuncId) -> ModuleResult<()> {
assert!(self.hotswap_enabled, "Hotswap support is not enabled");
let decl = self.declarations.get_function_decl(func_id);
if !decl.linkage.is_definable() {
return Err(ModuleError::InvalidImportDefinition(decl.name.clone()));
}
if self.compiled_functions[func_id].is_none() {
return Err(ModuleError::Backend(anyhow::anyhow!(
"Tried to redefine not yet defined function {}",
decl.name
)));
}
self.compiled_functions[func_id] = None;
// FIXME return some kind of handle that allows for deallocating the function
Ok(())
}
}
impl Module for JITModule {
fn isa(&self) -> &dyn TargetIsa {
&*self.isa
}
fn declarations(&self) -> &ModuleDeclarations {
&self.declarations
}
fn declare_function(
&mut self,
name: &str,
linkage: Linkage,
signature: &ir::Signature,
) -> ModuleResult<FuncId> {
let (id, _decl) = self
.declarations
.declare_function(name, linkage, signature)?;
if self.function_got_entries[id].is_none() && self.isa.flags().is_pic() {
let got_entry = self
.memory
.writable
.allocate(
std::mem::size_of::<*const u8>(),
std::mem::align_of::<*const u8>().try_into().unwrap(),
)
.unwrap()
.cast::<*const u8>();
self.function_got_entries[id] = Some(NonNull::new(got_entry).unwrap());
// FIXME populate got entries with a null pointer when defined
let val = self.lookup_symbol(name).unwrap_or(std::ptr::null());
unsafe {
std::ptr::write(got_entry, val);
}
let plt_entry = self
.memory
.code
.allocate(std::mem::size_of::<[u8; 16]>(), EXECUTABLE_DATA_ALIGNMENT)
.unwrap()
.cast::<[u8; 16]>();
self.record_function_for_perf(
plt_entry as *mut _,
std::mem::size_of::<[u8; 16]>(),
&format!("{}@plt", name),
);
self.function_plt_entries[id] = Some(NonNull::new(plt_entry).unwrap());
unsafe {
Self::write_plt_entry_bytes(plt_entry, got_entry);
}
}
Ok(id)
}
fn declare_data(
&mut self,
name: &str,
linkage: Linkage,
writable: bool,
tls: bool,
) -> ModuleResult<DataId> {
assert!(!tls, "JIT doesn't yet support TLS");
let (id, _decl) = self
.declarations
.declare_data(name, linkage, writable, tls)?;
if self.data_object_got_entries[id].is_none() && self.isa.flags().is_pic() {
let got_entry = self
.memory
.writable
.allocate(
std::mem::size_of::<*const u8>(),
std::mem::align_of::<*const u8>().try_into().unwrap(),
)
.unwrap()
.cast::<*const u8>();
self.data_object_got_entries[id] = Some(NonNull::new(got_entry).unwrap());
// FIXME populate got entries with a null pointer when defined
let val = self.lookup_symbol(name).unwrap_or(std::ptr::null());
unsafe {
std::ptr::write(got_entry, val);
}
}
Ok(id)
}
/// Use this when you're building the IR of a function to reference a function.
///
/// TODO: Coalesce redundant decls and signatures.
/// TODO: Look into ways to reduce the risk of using a FuncRef in the wrong function.
fn declare_func_in_func(&self, func: FuncId, in_func: &mut ir::Function) -> ir::FuncRef {
let decl = self.declarations.get_function_decl(func);
let signature = in_func.import_signature(decl.signature.clone());
let colocated = !self.hotswap_enabled && decl.linkage.is_final();
in_func.import_function(ir::ExtFuncData {
name: ir::ExternalName::user(0, func.as_u32()),
signature,
colocated,
})
}
/// Use this when you're building the IR of a function to reference a data object.
///
/// TODO: Same as above.
fn declare_data_in_func(&self, data: DataId, func: &mut ir::Function) -> ir::GlobalValue {
let decl = self.declarations.get_data_decl(data);
let colocated = !self.hotswap_enabled && decl.linkage.is_final();
func.create_global_value(ir::GlobalValueData::Symbol {
name: ir::ExternalName::user(1, data.as_u32()),
offset: ir::immediates::Imm64::new(0),
colocated,
tls: decl.tls,
})
}
/// TODO: Same as above.
fn declare_func_in_data(&self, func: FuncId, ctx: &mut DataContext) -> ir::FuncRef {
ctx.import_function(ir::ExternalName::user(0, func.as_u32()))
}
/// TODO: Same as above.
fn declare_data_in_data(&self, data: DataId, ctx: &mut DataContext) -> ir::GlobalValue {
ctx.import_global_value(ir::ExternalName::user(1, data.as_u32()))
}
fn define_function<TS>(
&mut self,
id: FuncId,
ctx: &mut cranelift_codegen::Context,
trap_sink: &mut TS,
) -> ModuleResult<ModuleCompiledFunction>
where
TS: TrapSink,
{
info!("defining function {}: {}", id, ctx.func.display(self.isa()));
let CodeInfo {
total_size: code_size,
..
} = ctx.compile(self.isa())?;
let decl = self.declarations.get_function_decl(id);
if !decl.linkage.is_definable() {
return Err(ModuleError::InvalidImportDefinition(decl.name.clone()));
}
if !self.compiled_functions[id].is_none() {
return Err(ModuleError::DuplicateDefinition(decl.name.to_owned()));
}
let size = code_size as usize;
let ptr = self
.memory
.code
.allocate(size, EXECUTABLE_DATA_ALIGNMENT)
.expect("TODO: handle OOM etc.");
let mut reloc_sink = JITRelocSink::default();
let mut stack_map_sink = binemit::NullStackMapSink {};
unsafe {
ctx.emit_to_memory(
&*self.isa,
ptr,
&mut reloc_sink,
trap_sink,
&mut stack_map_sink,
)
};
self.record_function_for_perf(ptr, size, &decl.name);
self.compiled_functions[id] = Some(CompiledBlob {
ptr,
size,
relocs: reloc_sink.relocs,
});
if self.isa.flags().is_pic() {
unsafe {
std::ptr::write(self.function_got_entries[id].unwrap().as_ptr(), ptr);
}
}
if self.hotswap_enabled {
self.compiled_functions[id]
.as_ref()
.unwrap()
.perform_relocations(
|name| match *name {
ir::ExternalName::User { .. } => {
unreachable!("non GOT or PLT relocation in function {} to {}", id, name)
}
ir::ExternalName::LibCall(ref libcall) => self
.libcall_plt_entries
.get(libcall)
.unwrap_or_else(|| panic!("can't resolve libcall {}", libcall))
.as_ptr()
.cast::<u8>(),
_ => panic!("invalid ExternalName {}", name),
},
|name| self.get_got_address(name),
|name| self.get_plt_address(name),
);
} else {
self.functions_to_finalize.push(id);
}
Ok(ModuleCompiledFunction { size: code_size })
}
fn define_function_bytes(
&mut self,
id: FuncId,
bytes: &[u8],
relocs: &[RelocRecord],
) -> ModuleResult<ModuleCompiledFunction> {
info!("defining function {} with bytes", id);
let total_size: u32 = match bytes.len().try_into() {
Ok(total_size) => total_size,
_ => Err(CodegenError::CodeTooLarge)?,
};
let decl = self.declarations.get_function_decl(id);
if !decl.linkage.is_definable() {
return Err(ModuleError::InvalidImportDefinition(decl.name.clone()));
}
if !self.compiled_functions[id].is_none() {
return Err(ModuleError::DuplicateDefinition(decl.name.to_owned()));
}
let size = bytes.len();
let ptr = self
.memory
.code
.allocate(size, EXECUTABLE_DATA_ALIGNMENT)
.expect("TODO: handle OOM etc.");
unsafe {
ptr::copy_nonoverlapping(bytes.as_ptr(), ptr, size);
}
self.record_function_for_perf(ptr, size, &decl.name);
self.compiled_functions[id] = Some(CompiledBlob {
ptr,
size,
relocs: relocs.to_vec(),
});
if self.isa.flags().is_pic() {
unsafe {
std::ptr::write(self.function_got_entries[id].unwrap().as_ptr(), ptr);
}
}
if self.hotswap_enabled {
self.compiled_functions[id]
.as_ref()
.unwrap()
.perform_relocations(
|name| unreachable!("non GOT or PLT relocation in function {} to {}", id, name),
|name| self.get_got_address(name),
|name| self.get_plt_address(name),
);
} else {
self.functions_to_finalize.push(id);
}
Ok(ModuleCompiledFunction { size: total_size })
}
fn define_data(&mut self, id: DataId, data: &DataContext) -> ModuleResult<()> {
let decl = self.declarations.get_data_decl(id);
if !decl.linkage.is_definable() {
return Err(ModuleError::InvalidImportDefinition(decl.name.clone()));
}
if !self.compiled_data_objects[id].is_none() {
return Err(ModuleError::DuplicateDefinition(decl.name.to_owned()));
}
assert!(!decl.tls, "JIT doesn't yet support TLS");
let &DataDescription {
ref init,
function_decls: _,
data_decls: _,
function_relocs: _,
data_relocs: _,
custom_segment_section: _,
align,
} = data.description();
let size = init.size();
let ptr = if decl.writable {
self.memory
.writable
.allocate(size, align.unwrap_or(WRITABLE_DATA_ALIGNMENT))
.expect("TODO: handle OOM etc.")
} else {
self.memory
.readonly
.allocate(size, align.unwrap_or(READONLY_DATA_ALIGNMENT))
.expect("TODO: handle OOM etc.")
};
match *init {
Init::Uninitialized => {
panic!("data is not initialized yet");
}
Init::Zeros { .. } => {
unsafe { ptr::write_bytes(ptr, 0, size) };
}
Init::Bytes { ref contents } => {
let src = contents.as_ptr();
unsafe { ptr::copy_nonoverlapping(src, ptr, size) };
}
}
let pointer_reloc = match self.isa.triple().pointer_width().unwrap() {
PointerWidth::U16 => panic!(),
PointerWidth::U32 => Reloc::Abs4,
PointerWidth::U64 => Reloc::Abs8,
};
let relocs = data
.description()
.all_relocs(pointer_reloc)
.collect::<Vec<_>>();
self.compiled_data_objects[id] = Some(CompiledBlob { ptr, size, relocs });
self.data_objects_to_finalize.push(id);
if self.isa.flags().is_pic() {
unsafe {
std::ptr::write(self.data_object_got_entries[id].unwrap().as_ptr(), ptr);
}
}
Ok(())
}
}
#[cfg(not(windows))]
fn lookup_with_dlsym(name: &str) -> Option<*const u8> {
let c_str = CString::new(name).unwrap();
let c_str_ptr = c_str.as_ptr();
let sym = unsafe { libc::dlsym(libc::RTLD_DEFAULT, c_str_ptr) };
if sym.is_null() {
None
} else {
Some(sym as *const u8)
}
}
#[cfg(windows)]
fn lookup_with_dlsym(name: &str) -> Option<*const u8> {
const MSVCRT_DLL: &[u8] = b"msvcrt.dll\0";
let c_str = CString::new(name).unwrap();
let c_str_ptr = c_str.as_ptr();
unsafe {
let handles = [
// try to find the searched symbol in the currently running executable
ptr::null_mut(),
// try to find the searched symbol in local c runtime
winapi::um::libloaderapi::GetModuleHandleA(MSVCRT_DLL.as_ptr() as *const i8),
];
for handle in &handles {
let addr = winapi::um::libloaderapi::GetProcAddress(*handle, c_str_ptr);
if addr.is_null() {
continue;
}
return Some(addr as *const u8);
}
None
}
}
#[derive(Default)]
struct JITRelocSink {
relocs: Vec<RelocRecord>,
}
impl RelocSink for JITRelocSink {
fn reloc_external(
&mut self,
offset: CodeOffset,
_srcloc: ir::SourceLoc,
reloc: Reloc,
name: &ir::ExternalName,
addend: Addend,
) {
self.relocs.push(RelocRecord {
offset,
reloc,
name: name.clone(),
addend,
});
}
fn reloc_jt(&mut self, _offset: CodeOffset, reloc: Reloc, _jt: ir::JumpTable) {
match reloc {
Reloc::X86PCRelRodata4 => {
// Not necessary to record this unless we are going to split apart code and its
// jumptbl/rodata.
}
_ => {
panic!("Unhandled reloc");
}
}
}
fn reloc_constant(&mut self, _offset: CodeOffset, reloc: Reloc, _constant: ir::ConstantOffset) {
match reloc {
Reloc::X86PCRelRodata4 => {
// Not necessary to record this unless we are going to split apart code and its
// jumptbl/rodata.
}
_ => {
panic!("Unhandled reloc");
}
}
}
}

79
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use cranelift_codegen::binemit::Reloc;
use cranelift_codegen::ir::ExternalName;
use cranelift_module::RelocRecord;
use std::convert::TryFrom;
#[derive(Clone)]
pub(crate) struct CompiledBlob {
pub(crate) ptr: *mut u8,
pub(crate) size: usize,
pub(crate) relocs: Vec<RelocRecord>,
}
impl CompiledBlob {
pub(crate) fn perform_relocations(
&self,
get_address: impl Fn(&ExternalName) -> *const u8,
get_got_entry: impl Fn(&ExternalName) -> *const u8,
get_plt_entry: impl Fn(&ExternalName) -> *const u8,
) {
use std::ptr::write_unaligned;
for &RelocRecord {
reloc,
offset,
ref name,
addend,
} in &self.relocs
{
debug_assert!((offset as usize) < self.size);
let at = unsafe { self.ptr.offset(isize::try_from(offset).unwrap()) };
match reloc {
Reloc::Abs4 => {
let base = get_address(name);
let what = unsafe { base.offset(isize::try_from(addend).unwrap()) };
#[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
unsafe {
write_unaligned(at as *mut u32, u32::try_from(what as usize).unwrap())
};
}
Reloc::Abs8 => {
let base = get_address(name);
let what = unsafe { base.offset(isize::try_from(addend).unwrap()) };
#[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
unsafe {
write_unaligned(at as *mut u64, u64::try_from(what as usize).unwrap())
};
}
Reloc::X86PCRel4 | Reloc::X86CallPCRel4 => {
let base = get_address(name);
let what = unsafe { base.offset(isize::try_from(addend).unwrap()) };
let pcrel = i32::try_from((what as isize) - (at as isize)).unwrap();
#[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
unsafe {
write_unaligned(at as *mut i32, pcrel)
};
}
Reloc::X86GOTPCRel4 => {
let base = get_got_entry(name);
let what = unsafe { base.offset(isize::try_from(addend).unwrap()) };
let pcrel = i32::try_from((what as isize) - (at as isize)).unwrap();
#[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
unsafe {
write_unaligned(at as *mut i32, pcrel)
};
}
Reloc::X86CallPLTRel4 => {
let base = get_plt_entry(name);
let what = unsafe { base.offset(isize::try_from(addend).unwrap()) };
let pcrel = i32::try_from((what as isize) - (at as isize)).unwrap();
#[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
unsafe {
write_unaligned(at as *mut i32, pcrel)
};
}
_ => unimplemented!(),
}
}
}
}

33
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//! Top-level lib.rs for `cranelift_jit`.
#![deny(
missing_docs,
trivial_numeric_casts,
unused_extern_crates,
unstable_features,
unreachable_pub
)]
#![warn(unused_import_braces)]
#![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../../clippy.toml")))]
#![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
#![cfg_attr(
feature = "cargo-clippy",
warn(
clippy::float_arithmetic,
clippy::mut_mut,
clippy::nonminimal_bool,
clippy::map_unwrap_or,
clippy::clippy::print_stdout,
clippy::unicode_not_nfc,
clippy::use_self
)
)]
mod backend;
mod compiled_blob;
mod memory;
pub use crate::backend::{JITBuilder, JITModule};
/// Version number of this crate.
pub const VERSION: &str = env!("CARGO_PKG_VERSION");

260
cranelift/jit/src/memory.rs Normal file
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#[cfg(not(feature = "selinux-fix"))]
use errno;
#[cfg(not(any(feature = "selinux-fix", windows)))]
use libc;
#[cfg(feature = "selinux-fix")]
use memmap::MmapMut;
use region;
use std::convert::TryFrom;
use std::mem;
use std::ptr;
/// Round `size` up to the nearest multiple of `page_size`.
fn round_up_to_page_size(size: usize, page_size: usize) -> usize {
(size + (page_size - 1)) & !(page_size - 1)
}
/// A simple struct consisting of a pointer and length.
struct PtrLen {
#[cfg(feature = "selinux-fix")]
map: Option<MmapMut>,
ptr: *mut u8,
len: usize,
}
impl PtrLen {
/// Create a new empty `PtrLen`.
fn new() -> Self {
Self {
#[cfg(feature = "selinux-fix")]
map: None,
ptr: ptr::null_mut(),
len: 0,
}
}
/// Create a new `PtrLen` pointing to at least `size` bytes of memory,
/// suitably sized and aligned for memory protection.
#[cfg(all(not(target_os = "windows"), feature = "selinux-fix"))]
fn with_size(size: usize) -> Result<Self, String> {
let page_size = region::page::size();
let alloc_size = round_up_to_page_size(size, page_size);
let map = MmapMut::map_anon(alloc_size);
match map {
Ok(mut map) => {
// The order here is important; we assign the pointer first to get
// around compile time borrow errors.
Ok(Self {
ptr: map.as_mut_ptr(),
map: Some(map),
len: alloc_size,
})
}
Err(e) => Err(e.to_string()),
}
}
#[cfg(all(not(target_os = "windows"), not(feature = "selinux-fix")))]
fn with_size(size: usize) -> Result<Self, String> {
let mut ptr = ptr::null_mut();
let page_size = region::page::size();
let alloc_size = round_up_to_page_size(size, page_size);
unsafe {
let err = libc::posix_memalign(&mut ptr, page_size, alloc_size);
if err == 0 {
Ok(Self {
ptr: ptr as *mut u8,
len: alloc_size,
})
} else {
Err(errno::Errno(err).to_string())
}
}
}
#[cfg(target_os = "windows")]
fn with_size(size: usize) -> Result<Self, String> {
use winapi::um::memoryapi::VirtualAlloc;
use winapi::um::winnt::{MEM_COMMIT, MEM_RESERVE, PAGE_READWRITE};
let page_size = region::page::size();
// VirtualAlloc always rounds up to the next multiple of the page size
let ptr = unsafe {
VirtualAlloc(
ptr::null_mut(),
size,
MEM_COMMIT | MEM_RESERVE,
PAGE_READWRITE,
)
};
if !ptr.is_null() {
Ok(Self {
ptr: ptr as *mut u8,
len: round_up_to_page_size(size, page_size),
})
} else {
Err(errno::errno().to_string())
}
}
}
// `MMapMut` from `cfg(feature = "selinux-fix")` already deallocates properly.
#[cfg(all(not(target_os = "windows"), not(feature = "selinux-fix")))]
impl Drop for PtrLen {
fn drop(&mut self) {
if !self.ptr.is_null() {
unsafe {
region::protect(self.ptr, self.len, region::Protection::READ_WRITE)
.expect("unable to unprotect memory");
libc::free(self.ptr as _);
}
}
}
}
// TODO: add a `Drop` impl for `cfg(target_os = "windows")`
/// JIT memory manager. This manages pages of suitably aligned and
/// accessible memory. Memory will be leaked by default to have
/// function pointers remain valid for the remainder of the
/// program's life.
pub(crate) struct Memory {
allocations: Vec<PtrLen>,
executable: usize,
current: PtrLen,
position: usize,
}
impl Memory {
pub(crate) fn new() -> Self {
Self {
allocations: Vec::new(),
executable: 0,
current: PtrLen::new(),
position: 0,
}
}
fn finish_current(&mut self) {
self.allocations
.push(mem::replace(&mut self.current, PtrLen::new()));
self.position = 0;
}
/// TODO: Use a proper error type.
pub(crate) fn allocate(&mut self, size: usize, align: u64) -> Result<*mut u8, String> {
let align = usize::try_from(align).expect("alignment too big");
if self.position % align != 0 {
self.position += align - self.position % align;
debug_assert!(self.position % align == 0);
}
if size <= self.current.len - self.position {
// TODO: Ensure overflow is not possible.
let ptr = unsafe { self.current.ptr.add(self.position) };
self.position += size;
return Ok(ptr);
}
self.finish_current();
// TODO: Allocate more at a time.
self.current = PtrLen::with_size(size)?;
self.position = size;
Ok(self.current.ptr)
}
/// Set all memory allocated in this `Memory` up to now as readable and executable.
pub(crate) fn set_readable_and_executable(&mut self) {
self.finish_current();
#[cfg(feature = "selinux-fix")]
{
for &PtrLen { ref map, ptr, len } in &self.allocations[self.executable..] {
if len != 0 && map.is_some() {
unsafe {
region::protect(ptr, len, region::Protection::READ_EXECUTE)
.expect("unable to make memory readable+executable");
}
}
}
}
#[cfg(not(feature = "selinux-fix"))]
{
for &PtrLen { ptr, len } in &self.allocations[self.executable..] {
if len != 0 {
unsafe {
region::protect(ptr, len, region::Protection::READ_EXECUTE)
.expect("unable to make memory readable+executable");
}
}
}
}
}
/// Set all memory allocated in this `Memory` up to now as readonly.
pub(crate) fn set_readonly(&mut self) {
self.finish_current();
#[cfg(feature = "selinux-fix")]
{
for &PtrLen { ref map, ptr, len } in &self.allocations[self.executable..] {
if len != 0 && map.is_some() {
unsafe {
region::protect(ptr, len, region::Protection::READ)
.expect("unable to make memory readonly");
}
}
}
}
#[cfg(not(feature = "selinux-fix"))]
{
for &PtrLen { ptr, len } in &self.allocations[self.executable..] {
if len != 0 {
unsafe {
region::protect(ptr, len, region::Protection::READ)
.expect("unable to make memory readonly");
}
}
}
}
}
/// Frees all allocated memory regions that would be leaked otherwise.
/// Likely to invalidate existing function pointers, causing unsafety.
pub(crate) unsafe fn free_memory(&mut self) {
self.allocations.clear();
}
}
impl Drop for Memory {
fn drop(&mut self) {
// leak memory to guarantee validity of function pointers
mem::replace(&mut self.allocations, Vec::new())
.into_iter()
.for_each(mem::forget);
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_round_up_to_page_size() {
assert_eq!(round_up_to_page_size(0, 4096), 0);
assert_eq!(round_up_to_page_size(1, 4096), 4096);
assert_eq!(round_up_to_page_size(4096, 4096), 4096);
assert_eq!(round_up_to_page_size(4097, 4096), 8192);
}
}

213
cranelift/jit/tests/basic.rs Normal file
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@@ -0,0 +1,213 @@
use cranelift_codegen::binemit::NullTrapSink;
use cranelift_codegen::ir::*;
use cranelift_codegen::isa::CallConv;
use cranelift_codegen::settings::{self, Configurable};
use cranelift_codegen::{ir::types::I16, Context};
use cranelift_entity::EntityRef;
use cranelift_frontend::*;
use cranelift_jit::*;
use cranelift_module::*;
#[test]
fn error_on_incompatible_sig_in_declare_function() {
let mut flag_builder = settings::builder();
flag_builder.set("use_colocated_libcalls", "false").unwrap();
// FIXME set back to true once the x64 backend supports it.
flag_builder.set("is_pic", "false").unwrap();
let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
panic!("host machine is not supported: {}", msg);
});
let isa = isa_builder.finish(settings::Flags::new(flag_builder));
let mut module = JITModule::new(JITBuilder::with_isa(isa, default_libcall_names()));
let mut sig = Signature {
params: vec![AbiParam::new(types::I64)],
returns: vec![],
call_conv: CallConv::SystemV,
};
module
.declare_function("abc", Linkage::Local, &sig)
.unwrap();
sig.params[0] = AbiParam::new(types::I32);
module
.declare_function("abc", Linkage::Local, &sig)
.err()
.unwrap(); // Make sure this is an error
}
fn define_simple_function(module: &mut JITModule) -> FuncId {
let sig = Signature {
params: vec![],
returns: vec![],
call_conv: CallConv::SystemV,
};
let func_id = module
.declare_function("abc", Linkage::Local, &sig)
.unwrap();
let mut ctx = Context::new();
ctx.func = Function::with_name_signature(ExternalName::user(0, func_id.as_u32()), sig);
let mut func_ctx = FunctionBuilderContext::new();
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
bcx.ins().return_(&[]);
}
let mut trap_sink = NullTrapSink {};
module
.define_function(func_id, &mut ctx, &mut trap_sink)
.unwrap();
func_id
}
#[test]
#[should_panic(expected = "Result::unwrap()` on an `Err` value: DuplicateDefinition(\"abc\")")]
fn panic_on_define_after_finalize() {
let mut flag_builder = settings::builder();
flag_builder.set("use_colocated_libcalls", "false").unwrap();
// FIXME set back to true once the x64 backend supports it.
flag_builder.set("is_pic", "false").unwrap();
let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
panic!("host machine is not supported: {}", msg);
});
let isa = isa_builder.finish(settings::Flags::new(flag_builder));
let mut module = JITModule::new(JITBuilder::with_isa(isa, default_libcall_names()));
define_simple_function(&mut module);
define_simple_function(&mut module);
}
#[test]
fn switch_error() {
use cranelift_codegen::settings;
let sig = Signature {
params: vec![AbiParam::new(types::I32)],
returns: vec![AbiParam::new(types::I32)],
call_conv: CallConv::SystemV,
};
let mut func = Function::with_name_signature(ExternalName::user(0, 0), sig);
let mut func_ctx = FunctionBuilderContext::new();
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut func, &mut func_ctx);
let start = bcx.create_block();
let bb0 = bcx.create_block();
let bb1 = bcx.create_block();
let bb2 = bcx.create_block();
let bb3 = bcx.create_block();
println!("{} {} {} {} {}", start, bb0, bb1, bb2, bb3);
bcx.declare_var(Variable::new(0), types::I32);
bcx.declare_var(Variable::new(1), types::I32);
let in_val = bcx.append_block_param(start, types::I32);
bcx.switch_to_block(start);
bcx.def_var(Variable::new(0), in_val);
bcx.ins().jump(bb0, &[]);
bcx.switch_to_block(bb0);
let discr = bcx.use_var(Variable::new(0));
let mut switch = cranelift_frontend::Switch::new();
for &(index, bb) in &[
(9, bb1),
(13, bb1),
(10, bb1),
(92, bb1),
(39, bb1),
(34, bb1),
] {
switch.set_entry(index, bb);
}
switch.emit(&mut bcx, discr, bb2);
bcx.switch_to_block(bb1);
let v = bcx.use_var(Variable::new(0));
bcx.def_var(Variable::new(1), v);
bcx.ins().jump(bb3, &[]);
bcx.switch_to_block(bb2);
let v = bcx.use_var(Variable::new(0));
bcx.def_var(Variable::new(1), v);
bcx.ins().jump(bb3, &[]);
bcx.switch_to_block(bb3);
let r = bcx.use_var(Variable::new(1));
bcx.ins().return_(&[r]);
bcx.seal_all_blocks();
bcx.finalize();
}
let flags = settings::Flags::new(settings::builder());
match cranelift_codegen::verify_function(&func, &flags) {
Ok(_) => {}
Err(err) => {
let pretty_error =
cranelift_codegen::print_errors::pretty_verifier_error(&func, None, None, err);
panic!("pretty_error:\n{}", pretty_error);
}
}
}
#[test]
fn libcall_function() {
let mut flag_builder = settings::builder();
flag_builder.set("use_colocated_libcalls", "false").unwrap();
// FIXME set back to true once the x64 backend supports it.
flag_builder.set("is_pic", "false").unwrap();
let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
panic!("host machine is not supported: {}", msg);
});
let isa = isa_builder.finish(settings::Flags::new(flag_builder));
let mut module = JITModule::new(JITBuilder::with_isa(isa, default_libcall_names()));
let sig = Signature {
params: vec![],
returns: vec![],
call_conv: CallConv::SystemV,
};
let func_id = module
.declare_function("function", Linkage::Local, &sig)
.unwrap();
let mut ctx = Context::new();
ctx.func = Function::with_name_signature(ExternalName::user(0, func_id.as_u32()), sig);
let mut func_ctx = FunctionBuilderContext::new();
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
let int = module.target_config().pointer_type();
let zero = bcx.ins().iconst(I16, 0);
let size = bcx.ins().iconst(int, 10);
let mut signature = module.make_signature();
signature.params.push(AbiParam::new(int));
signature.returns.push(AbiParam::new(int));
let callee = module
.declare_function("malloc", Linkage::Import, &signature)
.expect("declare malloc function");
let local_callee = module.declare_func_in_func(callee, &mut bcx.func);
let argument_exprs = vec![size];
let call = bcx.ins().call(local_callee, &argument_exprs);
let buffer = bcx.inst_results(call)[0];
bcx.call_memset(module.target_config(), buffer, zero, size);
bcx.ins().return_(&[]);
}
let mut trap_sink = NullTrapSink {};
module
.define_function(func_id, &mut ctx, &mut trap_sink)
.unwrap();
module.finalize_definitions();
}