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interpret: clean up deduplicating allocation functions

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This commit is contained in:
Ralf Jung 2024-12-09 08:52:23 +01:00
parent f33a8c6426
commit 73dc95dad1
8 changed files with 23 additions and 137 deletions
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36
compiler/rustc_const_eval/src/interpret/place.rs
View file

@ -5,8 +5,7 @@
use std::assert_matches::assert_matches;
use either::{Either, Left, Right};
use rustc_abi::{Align, BackendRepr, HasDataLayout, Size};
use rustc_ast::Mutability;
use rustc_abi::{BackendRepr, HasDataLayout, Size};
use rustc_middle::ty::Ty;
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_middle::{bug, mir, span_bug};
@ -1018,40 +1017,31 @@ where
self.allocate_dyn(layout, kind, MemPlaceMeta::None)
}
/// Allocates a sequence of bytes in the interpreter's memory.
/// For immutable allocations, uses deduplication to reuse existing memory.
/// For mutable allocations, creates a new unique allocation.
pub fn allocate_bytes(
/// Allocates a sequence of bytes in the interpreter's memory with alignment 1.
/// This is allocated in immutable global memory and deduplicated.
pub fn allocate_bytes_dedup(
&mut self,
bytes: &[u8],
align: Align,
kind: MemoryKind<M::MemoryKind>,
mutbl: Mutability,
) -> InterpResult<'tcx, Pointer<M::Provenance>> {
// Use cache for immutable strings.
if mutbl.is_not() {
// Use dedup'd allocation function.
let salt = M::get_global_alloc_salt(self, None);
let id = self.tcx.allocate_bytes_dedup(bytes, salt);
// Turn untagged "global" pointers (obtained via `tcx`) into the machine pointer to the allocation.
M::adjust_alloc_root_pointer(&self, Pointer::from(id), Some(kind))
} else {
// Allocate new memory for mutable data.
self.allocate_bytes_ptr(bytes, align, kind, mutbl)
}
M::adjust_alloc_root_pointer(
&self,
Pointer::from(id),
M::GLOBAL_KIND.map(MemoryKind::Machine),
)
}
/// Allocates a string in the interpreter's memory with metadata for length.
/// Uses `allocate_bytes` internally but adds string-specific metadata handling.
pub fn allocate_str(
/// Allocates a string in the interpreter's memory, returning it as a (wide) place.
/// This is allocated in immutable global memory and deduplicated.
pub fn allocate_str_dedup(
&mut self,
str: &str,
kind: MemoryKind<M::MemoryKind>,
mutbl: Mutability,
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
let bytes = str.as_bytes();
let ptr = self.allocate_bytes(bytes, Align::ONE, kind, mutbl)?;
let ptr = self.allocate_bytes_dedup(bytes)?;
// Create length metadata for the string.
let meta = Scalar::from_target_usize(u64::try_from(bytes.len()).unwrap(), self);

9
compiler/rustc_const_eval/src/util/caller_location.rs
View file

@ -1,7 +1,7 @@
use rustc_hir::LangItem;
use rustc_middle::query::TyCtxtAt;
use rustc_middle::ty::layout::LayoutOf;
use rustc_middle::ty::{self, Mutability};
use rustc_middle::ty::{self};
use rustc_middle::{bug, mir};
use rustc_span::symbol::Symbol;
use tracing::trace;
@ -20,12 +20,9 @@ fn alloc_caller_location<'tcx>(
// This can fail if rustc runs out of memory right here. Trying to emit an error would be
// pointless, since that would require allocating more memory than these short strings.
let file = if loc_details.file {
ecx.allocate_str(filename.as_str(), MemoryKind::CallerLocation, Mutability::Not).unwrap()
ecx.allocate_str_dedup(filename.as_str()).unwrap()
} else {
// FIXME: This creates a new allocation each time. It might be preferable to
// perform this allocation only once, and re-use the `MPlaceTy`.
// See https://github.com/rust-lang/rust/pull/89920#discussion_r730012398
ecx.allocate_str("<redacted>", MemoryKind::CallerLocation, Mutability::Not).unwrap()
ecx.allocate_str_dedup("<redacted>").unwrap()
};
let file = file.map_provenance(CtfeProvenance::as_immutable);
let line = if loc_details.line { Scalar::from_u32(line) } else { Scalar::from_u32(0) };

2
compiler/rustc_middle/src/ty/context.rs
View file

@ -1479,7 +1479,7 @@ impl<'tcx> TyCtxt<'tcx> {
self.mk_adt_def_from_data(ty::AdtDefData::new(self, did, kind, variants, repr))
}
/// Allocates a read-only byte or string literal for `mir::interpret`.
/// Allocates a read-only byte or string literal for `mir::interpret` with alignment 1.
/// Returns the same `AllocId` if called again with the same bytes.
pub fn allocate_bytes_dedup(self, bytes: &[u8], salt: usize) -> interpret::AllocId {
// Create an allocation that just contains these bytes.

10
src/tools/miri/src/shims/backtrace.rs
View file

@ -1,5 +1,4 @@
use rustc_abi::{ExternAbi, Size};
use rustc_ast::ast::Mutability;
use rustc_middle::ty::layout::LayoutOf as _;
use rustc_middle::ty::{self, Instance, Ty};
use rustc_span::{BytePos, Loc, Symbol, hygiene};
@ -179,14 +178,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
match flags {
0 => {
// These are "mutable" allocations as we consider them to be owned by the callee.
let name_alloc =
this.allocate_str(&name, MiriMemoryKind::Rust.into(), Mutability::Mut)?;
let filename_alloc =
this.allocate_str(&filename, MiriMemoryKind::Rust.into(), Mutability::Mut)?;
this.write_immediate(name_alloc.to_ref(this), &this.project_field(dest, 0)?)?;
this.write_immediate(filename_alloc.to_ref(this), &this.project_field(dest, 1)?)?;
throw_unsup_format!("miri_resolve_frame: v0 is not supported any more");
}
1 => {
this.write_scalar(

5
src/tools/miri/src/shims/panic.rs
View file

@ -12,7 +12,6 @@
//! metadata we remembered when pushing said frame.
use rustc_abi::ExternAbi;
use rustc_ast::Mutability;
use rustc_middle::{mir, ty};
use rustc_target::spec::PanicStrategy;
@ -161,7 +160,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
let this = self.eval_context_mut();
// First arg: message.
let msg = this.allocate_str(msg, MiriMemoryKind::Machine.into(), Mutability::Not)?;
let msg = this.allocate_str_dedup(msg)?;
// Call the lang item.
let panic = this.tcx.lang_items().panic_fn().unwrap();
@ -180,7 +179,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
let this = self.eval_context_mut();
// First arg: message.
let msg = this.allocate_str(msg, MiriMemoryKind::Machine.into(), Mutability::Not)?;
let msg = this.allocate_str_dedup(msg)?;
// Call the lang item.
let panic = this.tcx.lang_items().panic_nounwind().unwrap();

69
src/tools/miri/tests/pass/backtrace/backtrace-api-v0.rs
View file

@ -1,69 +0,0 @@
//@normalize-stderr-test: "::<.*>" -> ""
#[inline(never)]
fn func_a() -> Box<[*mut ()]> {
func_b::<u8>()
}
#[inline(never)]
fn func_b<T>() -> Box<[*mut ()]> {
func_c()
}
macro_rules! invoke_func_d {
() => {
func_d()
};
}
#[inline(never)]
fn func_c() -> Box<[*mut ()]> {
invoke_func_d!()
}
#[inline(never)]
fn func_d() -> Box<[*mut ()]> {
unsafe { miri_get_backtrace(0) }
}
fn main() {
let mut seen_main = false;
let frames = func_a();
for frame in frames.iter() {
let miri_frame = unsafe { miri_resolve_frame(*frame, 0) };
let name = String::from_utf8(miri_frame.name.into()).unwrap();
let filename = String::from_utf8(miri_frame.filename.into()).unwrap();
if name == "func_a" {
assert_eq!(func_a as *mut (), miri_frame.fn_ptr);
}
// Print every frame to stderr.
let out = format!("{}:{}:{} ({})", filename, miri_frame.lineno, miri_frame.colno, name);
eprintln!("{}", out);
// Print the 'main' frame (and everything before it) to stdout, skipping
// the printing of internal (and possibly fragile) libstd frames.
// Stdout is less normalized so we see more, but it also means we can print less
// as platform differences would lead to test suite failures.
if !seen_main {
println!("{}", out);
seen_main = name == "main";
}
}
}
// This goes at the bottom of the file so that we can change it
// without disturbing line numbers of the functions in the backtrace.
extern "Rust" {
fn miri_get_backtrace(flags: u64) -> Box<[*mut ()]>;
fn miri_resolve_frame(ptr: *mut (), flags: u64) -> MiriFrame;
}
#[derive(Debug)]
#[repr(C)]
struct MiriFrame {
name: Box<[u8]>,
filename: Box<[u8]>,
lineno: u32,
colno: u32,
fn_ptr: *mut (),
}

18
src/tools/miri/tests/pass/backtrace/backtrace-api-v0.stderr
View file

@ -1,18 +0,0 @@
tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_d)
tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_c)
tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_b)
tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (func_a)
tests/pass/backtrace/backtrace-api-v0.rs:LL:CC (main)
RUSTLIB/core/src/ops/function.rs:LL:CC (<fn() as std::ops::FnOnce<()>>::call_once - shim(fn()))
RUSTLIB/std/src/sys/backtrace.rs:LL:CC (std::sys::backtrace::__rust_begin_short_backtrace)
RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start::{closure#0})
RUSTLIB/core/src/ops/function.rs:LL:CC (std::ops::function::impls::call_once)
RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try::do_call)
RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try)
RUSTLIB/std/src/panic.rs:LL:CC (std::panic::catch_unwind)
RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start_internal::{closure#1})
RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try::do_call)
RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try)
RUSTLIB/std/src/panic.rs:LL:CC (std::panic::catch_unwind)
RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start_internal)
RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start)

5
src/tools/miri/tests/pass/backtrace/backtrace-api-v0.stdout
View file

@ -1,5 +0,0 @@
tests/pass/backtrace/backtrace-api-v0.rs:24:14 (func_d)
tests/pass/backtrace/backtrace-api-v0.rs:14:9 (func_c)
tests/pass/backtrace/backtrace-api-v0.rs:9:5 (func_b::<u8>)
tests/pass/backtrace/backtrace-api-v0.rs:5:5 (func_a)
tests/pass/backtrace/backtrace-api-v0.rs:29:18 (main)