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Merge pull request rust-lang#4030 from YohDeadfall/ecx
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Renamed `this` to `ecx` in `extern_static`
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RalfJung authored Nov 12, 2024
2 parents a77ff2e + bd7772d commit 61d496e
Showing 1 changed file with 31 additions and 34 deletions.
65 changes: 31 additions & 34 deletions src/tools/miri/src/shims/extern_static.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,86 +4,83 @@ use crate::*;

impl<'tcx> MiriMachine<'tcx> {
fn alloc_extern_static(
this: &mut MiriInterpCx<'tcx>,
ecx: &mut MiriInterpCx<'tcx>,
name: &str,
val: ImmTy<'tcx>,
) -> InterpResult<'tcx> {
let place = this.allocate(val.layout, MiriMemoryKind::ExternStatic.into())?;
this.write_immediate(*val, &place)?;
Self::add_extern_static(this, name, place.ptr());
let place = ecx.allocate(val.layout, MiriMemoryKind::ExternStatic.into())?;
ecx.write_immediate(*val, &place)?;
Self::add_extern_static(ecx, name, place.ptr());
interp_ok(())
}

/// Zero-initialized pointer-sized extern statics are pretty common.
/// Most of them are for weak symbols, which we all set to null (indicating that the
/// symbol is not supported, and triggering fallback code which ends up calling
/// some other shim that we do support).
fn null_ptr_extern_statics(
this: &mut MiriInterpCx<'tcx>,
names: &[&str],
) -> InterpResult<'tcx> {
fn null_ptr_extern_statics(ecx: &mut MiriInterpCx<'tcx>, names: &[&str]) -> InterpResult<'tcx> {
for name in names {
let val = ImmTy::from_int(0, this.machine.layouts.usize);
Self::alloc_extern_static(this, name, val)?;
let val = ImmTy::from_int(0, ecx.machine.layouts.usize);
Self::alloc_extern_static(ecx, name, val)?;
}
interp_ok(())
}

/// Extern statics that are initialized with function pointers to the symbols of the same name.
fn weak_symbol_extern_statics(
this: &mut MiriInterpCx<'tcx>,
ecx: &mut MiriInterpCx<'tcx>,
names: &[&str],
) -> InterpResult<'tcx> {
for name in names {
assert!(this.is_dyn_sym(name), "{name} is not a dynamic symbol");
let layout = this.machine.layouts.const_raw_ptr;
let ptr = this.fn_ptr(FnVal::Other(DynSym::from_str(name)));
let val = ImmTy::from_scalar(Scalar::from_pointer(ptr, this), layout);
Self::alloc_extern_static(this, name, val)?;
assert!(ecx.is_dyn_sym(name), "{name} is not a dynamic symbol");
let layout = ecx.machine.layouts.const_raw_ptr;
let ptr = ecx.fn_ptr(FnVal::Other(DynSym::from_str(name)));
let val = ImmTy::from_scalar(Scalar::from_pointer(ptr, ecx), layout);
Self::alloc_extern_static(ecx, name, val)?;
}
interp_ok(())
}

/// Sets up the "extern statics" for this machine.
pub fn init_extern_statics(this: &mut MiriInterpCx<'tcx>) -> InterpResult<'tcx> {
pub fn init_extern_statics(ecx: &mut MiriInterpCx<'tcx>) -> InterpResult<'tcx> {
// "__rust_no_alloc_shim_is_unstable"
let val = ImmTy::from_int(0, this.machine.layouts.u8); // always 0, value does not matter
Self::alloc_extern_static(this, "__rust_no_alloc_shim_is_unstable", val)?;
let val = ImmTy::from_int(0, ecx.machine.layouts.u8); // always 0, value does not matter
Self::alloc_extern_static(ecx, "__rust_no_alloc_shim_is_unstable", val)?;

// "__rust_alloc_error_handler_should_panic"
let val = this.tcx.sess.opts.unstable_opts.oom.should_panic();
let val = ImmTy::from_int(val, this.machine.layouts.u8);
Self::alloc_extern_static(this, "__rust_alloc_error_handler_should_panic", val)?;
let val = ecx.tcx.sess.opts.unstable_opts.oom.should_panic();
let val = ImmTy::from_int(val, ecx.machine.layouts.u8);
Self::alloc_extern_static(ecx, "__rust_alloc_error_handler_should_panic", val)?;

if this.target_os_is_unix() {
if ecx.target_os_is_unix() {
// "environ" is mandated by POSIX.
let environ = this.machine.env_vars.unix().environ();
Self::add_extern_static(this, "environ", environ);
let environ = ecx.machine.env_vars.unix().environ();
Self::add_extern_static(ecx, "environ", environ);
}

match this.tcx.sess.target.os.as_ref() {
match ecx.tcx.sess.target.os.as_ref() {
"linux" => {
Self::null_ptr_extern_statics(this, &[
Self::null_ptr_extern_statics(ecx, &[
"__cxa_thread_atexit_impl",
"__clock_gettime64",
])?;
Self::weak_symbol_extern_statics(this, &["getrandom", "statx"])?;
Self::weak_symbol_extern_statics(ecx, &["getrandom", "statx"])?;
}
"freebsd" => {
Self::null_ptr_extern_statics(this, &["__cxa_thread_atexit_impl"])?;
Self::null_ptr_extern_statics(ecx, &["__cxa_thread_atexit_impl"])?;
}
"android" => {
Self::null_ptr_extern_statics(this, &["bsd_signal"])?;
Self::weak_symbol_extern_statics(this, &["signal", "getrandom"])?;
Self::null_ptr_extern_statics(ecx, &["bsd_signal"])?;
Self::weak_symbol_extern_statics(ecx, &["signal", "getrandom"])?;
}
"windows" => {
// "_tls_used"
// This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
let val = ImmTy::from_int(0, this.machine.layouts.u8);
Self::alloc_extern_static(this, "_tls_used", val)?;
let val = ImmTy::from_int(0, ecx.machine.layouts.u8);
Self::alloc_extern_static(ecx, "_tls_used", val)?;
}
"illumos" | "solaris" => {
Self::weak_symbol_extern_statics(this, &["pthread_setname_np"])?;
Self::weak_symbol_extern_statics(ecx, &["pthread_setname_np"])?;
}
_ => {} // No "extern statics" supported on this target
}
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