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miri: optimize zeroed alloc

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Co-authored-by: Ralf Jung <post@ralfj.de>
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SpecificProtagonist 2025-01-25 00:54:51 +01:00
parent 8231e8599e
commit eee9df43e6
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14 changed files with 88 additions and 79 deletions
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26
compiler/rustc_middle/src/mir/interpret/allocation.rs
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@ -270,6 +270,12 @@ impl AllocRange {
}
}
/// Whether a new allocation should be initialized with zero-bytes.
pub enum AllocInit {
Uninit,
Zero,
}
// The constructors are all without extra; the extra gets added by a machine hook later.
impl<Prov: Provenance, Bytes: AllocBytes> Allocation<Prov, (), Bytes> {
/// Creates an allocation initialized by the given bytes
@ -294,7 +300,12 @@ impl<Prov: Provenance, Bytes: AllocBytes> Allocation<Prov, (), Bytes> {
Allocation::from_bytes(slice, Align::ONE, Mutability::Not)
}
fn uninit_inner<R>(size: Size, align: Align, fail: impl FnOnce() -> R) -> Result<Self, R> {
fn new_inner<R>(
size: Size,
align: Align,
init: AllocInit,
fail: impl FnOnce() -> R,
) -> Result<Self, R> {
// We raise an error if we cannot create the allocation on the host.
// This results in an error that can happen non-deterministically, since the memory
// available to the compiler can change between runs. Normally queries are always
@ -306,7 +317,10 @@ impl<Prov: Provenance, Bytes: AllocBytes> Allocation<Prov, (), Bytes> {
Ok(Allocation {
bytes,
provenance: ProvenanceMap::new(),
init_mask: InitMask::new(size, false),
init_mask: InitMask::new(size, match init {
AllocInit::Uninit => false,
AllocInit::Zero => true,
}),
align,
mutability: Mutability::Mut,
extra: (),
@ -315,8 +329,8 @@ impl<Prov: Provenance, Bytes: AllocBytes> Allocation<Prov, (), Bytes> {
/// Try to create an Allocation of `size` bytes, failing if there is not enough memory
/// available to the compiler to do so.
pub fn try_uninit<'tcx>(size: Size, align: Align) -> InterpResult<'tcx, Self> {
Self::uninit_inner(size, align, || {
pub fn try_new<'tcx>(size: Size, align: Align, init: AllocInit) -> InterpResult<'tcx, Self> {
Self::new_inner(size, align, init, || {
ty::tls::with(|tcx| tcx.dcx().delayed_bug("exhausted memory during interpretation"));
InterpErrorKind::ResourceExhaustion(ResourceExhaustionInfo::MemoryExhausted)
})
@ -328,8 +342,8 @@ impl<Prov: Provenance, Bytes: AllocBytes> Allocation<Prov, (), Bytes> {
///
/// Example use case: To obtain an Allocation filled with specific data,
/// first call this function and then call write_scalar to fill in the right data.
pub fn uninit(size: Size, align: Align) -> Self {
match Self::uninit_inner(size, align, || {
pub fn new(size: Size, align: Align, init: AllocInit) -> Self {
match Self::new_inner(size, align, init, || {
panic!(
"interpreter ran out of memory: cannot create allocation of {} bytes",
size.bytes()