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Merged
merged 1 commit into from
Mar 28, 2025
+40 −33
Merged

cache mangle_internal_symbol results #4241

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13 changes: 13 additions & 0 deletions src/helpers.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, MaybeResult, TyAndLayout};
use rustc_middle::ty::{self, Binder, FloatTy, FnSig, IntTy, Ty, TyCtxt, UintTy};
use rustc_session::config::CrateType;
use rustc_span::{Span, Symbol};
use rustc_symbol_mangling::mangle_internal_symbol;
use rustc_target::callconv::{Conv, FnAbi};

use crate::*;
Expand Down Expand Up @@ -1258,6 +1259,18 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {

interp_ok(array)
}

fn mangle_internal_symbol<'a>(&'a mut self, name: &'static str) -> &'a str
where
'tcx: 'a,
{
let this = self.eval_context_mut();
let tcx = *this.tcx;
this.machine
.mangle_internal_symbol_cache
.entry(name)
.or_insert_with(|| mangle_internal_symbol(tcx, name))
}
}

impl<'tcx> MiriMachine<'tcx> {
Expand Down
5 changes: 5 additions & 0 deletions src/machine.rs
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Expand Up @@ -611,6 +611,9 @@ pub struct MiriMachine<'tcx> {
pub(crate) reject_in_isolation_warned: RefCell<FxHashSet<String>>,
/// Remembers which int2ptr casts we have already warned about.
pub(crate) int2ptr_warned: RefCell<FxHashSet<Span>>,

/// Cache for `mangle_internal_symbol`.
pub(crate) mangle_internal_symbol_cache: FxHashMap<&'static str, String>,
}

impl<'tcx> MiriMachine<'tcx> {
Expand Down Expand Up @@ -757,6 +760,7 @@ impl<'tcx> MiriMachine<'tcx> {
native_call_mem_warned: Cell::new(false),
reject_in_isolation_warned: Default::default(),
int2ptr_warned: Default::default(),
mangle_internal_symbol_cache: Default::default(),
}
}

Expand Down Expand Up @@ -930,6 +934,7 @@ impl VisitProvenance for MiriMachine<'_> {
native_call_mem_warned: _,
reject_in_isolation_warned: _,
int2ptr_warned: _,
mangle_internal_symbol_cache: _,
} = self;

threads.visit_provenance(visit);
Expand Down
55 changes: 22 additions & 33 deletions src/shims/foreign_items.rs
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Expand Up @@ -9,10 +9,9 @@ use rustc_hir::def::DefKind;
use rustc_hir::def_id::CrateNum;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc_middle::mir::interpret::AllocInit;
use rustc_middle::ty::Ty;
use rustc_middle::ty::{Instance, Ty};
use rustc_middle::{mir, ty};
use rustc_span::Symbol;
use rustc_symbol_mangling::mangle_internal_symbol;
use rustc_target::callconv::{Conv, FnAbi};

use self::helpers::{ToHost, ToSoft};
Expand Down Expand Up @@ -52,19 +51,19 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {

// Some shims forward to other MIR bodies.
match link_name.as_str() {
name if name == mangle_internal_symbol(*this.tcx, "__rust_alloc_error_handler") => {
name if name == this.mangle_internal_symbol("__rust_alloc_error_handler") => {
// Forward to the right symbol that implements this function.
let Some(handler_kind) = this.tcx.alloc_error_handler_kind(()) else {
// in real code, this symbol does not exist without an allocator
throw_unsup_format!(
"`__rust_alloc_error_handler` cannot be called when no alloc error handler is set"
);
};
let name =
mangle_internal_symbol(*this.tcx, alloc_error_handler_name(handler_kind));
let handler = this
.lookup_exported_symbol(Symbol::intern(&name))?
.expect("missing alloc error handler symbol");
let name = Symbol::intern(
this.mangle_internal_symbol(alloc_error_handler_name(handler_kind)),
);
let handler =
this.lookup_exported_symbol(name)?.expect("missing alloc error handler symbol");
return interp_ok(Some(handler));
}
_ => {}
Expand Down Expand Up @@ -138,30 +137,22 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
// Find it if it was not cached.
let mut instance_and_crate: Option<(ty::Instance<'_>, CrateNum)> = None;
helpers::iter_exported_symbols(tcx, |cnum, def_id| {
let attrs = tcx.codegen_fn_attrs(def_id);
// Skip over imports of items.
if tcx.is_foreign_item(def_id) {
// Skip over imports of items
return interp_ok(());
}

let attrs = tcx.codegen_fn_attrs(def_id);
// FIXME use tcx.symbol_name(instance) instead
let symbol_name = if let Some(export_name) = attrs.export_name {
export_name
} else if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE)
|| attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL)
// Skip over items without an explicitly defined symbol name.
if !(attrs.export_name.is_some()
|| attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE)
|| attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL))
{
tcx.item_name(def_id)
} else {
// Skip over items without an explicitly defined symbol name.
return interp_ok(());
};
let symbol_name =
if attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
Symbol::intern(&mangle_internal_symbol(tcx, symbol_name.as_str()))
} else {
symbol_name
};
if symbol_name == link_name {
}

let instance = Instance::mono(tcx, def_id);
let symbol_name = tcx.symbol_name(instance).name;
if symbol_name == link_name.as_str() {
if let Some((original_instance, original_cnum)) = instance_and_crate {
// Make sure we are consistent wrt what is 'first' and 'second'.
let original_span = tcx.def_span(original_instance.def_id()).data();
Expand Down Expand Up @@ -505,9 +496,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
}

// Rust allocation
name if name == mangle_internal_symbol(*this.tcx, "__rust_alloc")
|| name == "miri_alloc" =>
{
name if name == this.mangle_internal_symbol("__rust_alloc") || name == "miri_alloc" => {
let default = |ecx: &mut MiriInterpCx<'tcx>| {
// Only call `check_shim` when `#[global_allocator]` isn't used. When that
// macro is used, we act like no shim exists, so that the exported function can run.
Expand Down Expand Up @@ -540,7 +529,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
_ => return this.emulate_allocator(default),
}
}
name if name == mangle_internal_symbol(*this.tcx, "__rust_alloc_zeroed") => {
name if name == this.mangle_internal_symbol("__rust_alloc_zeroed") => {
return this.emulate_allocator(|this| {
// See the comment for `__rust_alloc` why `check_shim` is only called in the
// default case.
Expand All @@ -559,7 +548,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
this.write_pointer(ptr, dest)
});
}
name if name == mangle_internal_symbol(*this.tcx, "__rust_dealloc")
name if name == this.mangle_internal_symbol("__rust_dealloc")
|| name == "miri_dealloc" =>
{
let default = |ecx: &mut MiriInterpCx<'tcx>| {
Expand Down Expand Up @@ -592,7 +581,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
_ => return this.emulate_allocator(default),
}
}
name if name == mangle_internal_symbol(*this.tcx, "__rust_realloc") => {
name if name == this.mangle_internal_symbol("__rust_realloc") => {
return this.emulate_allocator(|this| {
// See the comment for `__rust_alloc` why `check_shim` is only called in the
// default case.
Expand Down