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interpret/memory: explain why we check is_thread_local_static

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This commit is contained in:
Ralf Jung 2023-12-23 16:48:29 +01:00
parent ef1b78eabe
commit c83bcbbad9
1 changed files with 6 additions and 0 deletions
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6
compiler/rustc_const_eval/src/interpret/memory.rs
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@ -165,6 +165,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// We need to handle `extern static`. // We need to handle `extern static`.
match self.tcx.try_get_global_alloc(alloc_id) { match self.tcx.try_get_global_alloc(alloc_id) {
Some(GlobalAlloc::Static(def_id)) if self.tcx.is_thread_local_static(def_id) => { Some(GlobalAlloc::Static(def_id)) if self.tcx.is_thread_local_static(def_id) => {
// Thread-local statics do not have a constant address. They *must* be accessed via
// `ThreadLocalRef`; we can never have a pointer to them as a regular constant value.
bug!("global memory cannot point to thread-local static") bug!("global memory cannot point to thread-local static")
} }
Some(GlobalAlloc::Static(def_id)) if self.tcx.is_foreign_item(def_id) => { Some(GlobalAlloc::Static(def_id)) if self.tcx.is_foreign_item(def_id) => {
@ -539,6 +541,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
None => throw_ub!(PointerUseAfterFree(id, CheckInAllocMsg::MemoryAccessTest)), None => throw_ub!(PointerUseAfterFree(id, CheckInAllocMsg::MemoryAccessTest)),
Some(GlobalAlloc::Static(def_id)) => { Some(GlobalAlloc::Static(def_id)) => {
assert!(self.tcx.is_static(def_id)); assert!(self.tcx.is_static(def_id));
// Thread-local statics do not have a constant address. They *must* be accessed via
// `ThreadLocalRef`; we can never have a pointer to them as a regular constant value.
assert!(!self.tcx.is_thread_local_static(def_id)); assert!(!self.tcx.is_thread_local_static(def_id));
// Notice that every static has two `AllocId` that will resolve to the same // Notice that every static has two `AllocId` that will resolve to the same
// thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID, // thing here: one maps to `GlobalAlloc::Static`, this is the "lazy" ID,
@ -740,6 +744,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
match self.tcx.try_get_global_alloc(id) { match self.tcx.try_get_global_alloc(id) {
Some(GlobalAlloc::Static(def_id)) => { Some(GlobalAlloc::Static(def_id)) => {
assert!(self.tcx.is_static(def_id)); assert!(self.tcx.is_static(def_id));
// Thread-local statics do not have a constant address. They *must* be accessed via
// `ThreadLocalRef`; we can never have a pointer to them as a regular constant value.
assert!(!self.tcx.is_thread_local_static(def_id)); assert!(!self.tcx.is_thread_local_static(def_id));
// Use size and align of the type. // Use size and align of the type.
let ty = self let ty = self