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ctfe interpreter: extend provenance so that it can track whether a pointer is immutable

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This commit is contained in:
Ralf Jung
2023-11-25 18:41:53 +01:00
parent 85a4bd8f58
commit cb86303342
38 changed files with 261 additions and 145 deletions
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24
compiler/rustc_const_eval/src/interpret/intern.rs
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@@ -18,7 +18,7 @@ use super::validity::RefTracking;
use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_middle::mir::interpret::InterpResult;
use rustc_middle::mir::interpret::{CtfeProvenance, InterpResult};
use rustc_middle::ty::{self, layout::TyAndLayout, Ty};
use rustc_ast::Mutability;
@@ -34,7 +34,7 @@ pub trait CompileTimeMachine<'mir, 'tcx: 'mir, T> = Machine<
'mir,
'tcx,
MemoryKind = T,
Provenance = AllocId,
Provenance = CtfeProvenance,
ExtraFnVal = !,
FrameExtra = (),
AllocExtra = (),
@@ -135,7 +135,7 @@ fn intern_shallow<'rt, 'mir, 'tcx, M: CompileTimeMachine<'mir, 'tcx, const_eval:
alloc.mutability = Mutability::Not;
};
// link the alloc id to the actual allocation
leftover_allocations.extend(alloc.provenance().ptrs().iter().map(|&(_, alloc_id)| alloc_id));
leftover_allocations.extend(alloc.provenance().ptrs().iter().map(|&(_, prov)| prov.alloc_id()));
let alloc = tcx.mk_const_alloc(alloc);
tcx.set_alloc_id_memory(alloc_id, alloc);
None
@@ -178,10 +178,10 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
tcx.struct_tail_erasing_lifetimes(referenced_ty, self.ecx.param_env).kind()
{
let ptr = mplace.meta().unwrap_meta().to_pointer(&tcx)?;
if let Some(alloc_id) = ptr.provenance {
if let Some(prov) = ptr.provenance {
// Explicitly choose const mode here, since vtables are immutable, even
// if the reference of the fat pointer is mutable.
self.intern_shallow(alloc_id, InternMode::Const, None);
self.intern_shallow(prov.alloc_id(), InternMode::Const, None);
} else {
// Validation will error (with a better message) on an invalid vtable pointer.
// Let validation show the error message, but make sure it *does* error.
@@ -191,7 +191,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
}
// Check if we have encountered this pointer+layout combination before.
// Only recurse for allocation-backed pointers.
if let Some(alloc_id) = mplace.ptr().provenance {
if let Some(prov) = mplace.ptr().provenance {
// Compute the mode with which we intern this. Our goal here is to make as many
// statics as we can immutable so they can be placed in read-only memory by LLVM.
let ref_mode = match self.mode {
@@ -234,7 +234,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
InternMode::Const
}
};
match self.intern_shallow(alloc_id, ref_mode, Some(referenced_ty)) {
match self.intern_shallow(prov.alloc_id(), ref_mode, Some(referenced_ty)) {
// No need to recurse, these are interned already and statics may have
// cycles, so we don't want to recurse there
Some(IsStaticOrFn) => {}
@@ -353,7 +353,7 @@ pub fn intern_const_alloc_recursive<
leftover_allocations,
// The outermost allocation must exist, because we allocated it with
// `Memory::allocate`.
ret.ptr().provenance.unwrap(),
ret.ptr().provenance.unwrap().alloc_id(),
base_intern_mode,
Some(ret.layout.ty),
);
@@ -431,7 +431,8 @@ pub fn intern_const_alloc_recursive<
}
let alloc = tcx.mk_const_alloc(alloc);
tcx.set_alloc_id_memory(alloc_id, alloc);
for &(_, alloc_id) in alloc.inner().provenance().ptrs().iter() {
for &(_, prov) in alloc.inner().provenance().ptrs().iter() {
let alloc_id = prov.alloc_id();
if leftover_allocations.insert(alloc_id) {
todo.push(alloc_id);
}
@@ -503,10 +504,11 @@ impl<'mir, 'tcx: 'mir, M: super::intern::CompileTimeMachine<'mir, 'tcx, !>>
// `allocate` picks a fresh AllocId that we will associate with its data below.
let dest = self.allocate(layout, MemoryKind::Stack)?;
f(self, &dest.clone().into())?;
let mut alloc = self.memory.alloc_map.remove(&dest.ptr().provenance.unwrap()).unwrap().1;
let mut alloc =
self.memory.alloc_map.remove(&dest.ptr().provenance.unwrap().alloc_id()).unwrap().1;
alloc.mutability = Mutability::Not;
let alloc = self.tcx.mk_const_alloc(alloc);
let alloc_id = dest.ptr().provenance.unwrap(); // this was just allocated, it must have provenance
let alloc_id = dest.ptr().provenance.unwrap().alloc_id(); // this was just allocated, it must have provenance
self.tcx.set_alloc_id_memory(alloc_id, alloc);
Ok(alloc_id)
}