rust/tests/mir-opt/reference_prop.rs

593 lines
16 KiB
Rust

// unit-test: ReferencePropagation
// needs-unwind
#![feature(raw_ref_op)]
#![feature(core_intrinsics, custom_mir)]
#[inline(never)]
fn opaque(_: impl Sized) {}
fn reference_propagation<'a, T: Copy>(single: &'a T, mut multiple: &'a T) {
// Propagation through a reference.
{
let a = 5_usize;
let b = &a; // This borrow is only used once.
let c = *b; // This should be optimized.
opaque(()); // We use opaque to separate cases into basic blocks in the MIR.
}
// Propagation through a two references.
{
let a = 5_usize;
let a2 = 7_usize;
let mut b = &a;
b = &a2;
// `b` is assigned twice, so we cannot propagate it.
let c = *b;
opaque(());
}
// Propagation through a borrowed reference.
{
let a = 5_usize;
let b = &a;
let d = &b;
let c = *b; // `b` is immutably borrowed, we know its value, but do not propagate it
opaque(d); // prevent `d` from being removed.
}
// Propagation through a borrowed reference.
{
let a = 5_usize;
let mut b = &a;
let d = &raw mut b;
let c = *b; // `b` is mutably borrowed, we cannot know its value.
opaque(d); // prevent `d` from being removed.
}
// Propagation through an escaping borrow.
{
let a = 7_usize;
let b = &a;
let c = *b;
opaque(b); // `b` escapes here, but we can still replace immutable borrow
}
// Propagation through a transitively escaping borrow.
{
let a = 7_usize;
let b1 = &a;
let c = *b1;
let b2 = b1;
let c2 = *b2;
let b3 = b2;
// `b3` escapes here, so we can only replace immutable borrow,
// for either `b`, `b2` or `b3`.
opaque(b3);
}
// Propagation a reborrow of an argument.
{
let a = &*single;
let b = *a; // This should be optimized as `*single`.
opaque(());
}
// Propagation a reborrow of a mutated argument.
{
let a = &*multiple;
multiple = &*single;
let b = *a; // This should not be optimized.
opaque(());
}
// Fixed-point propagation through a borrowed reference.
{
let a = 5_usize;
let b = &a;
let d = &b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
// Fixed-point propagation through a borrowed reference.
{
let a = 5_usize;
let mut b = &a;
let d = &mut b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
}
fn reference_propagation_mut<'a, T: Copy>(single: &'a mut T, mut multiple: &'a mut T) {
// Propagation through a reference.
{
let mut a = 5_usize;
let b = &mut a; // This borrow is only used once.
let c = *b; // This should be optimized.
opaque(());
}
// Propagation through a two references.
{
let mut a = 5_usize;
let mut a2 = 7_usize;
let mut b = &mut a;
b = &mut a2;
// `b` is assigned twice, so we cannot propagate it.
let c = *b;
opaque(());
}
// Propagation through a borrowed reference.
{
let mut a = 5_usize;
let b = &mut a;
let d = &b;
let c = *b; // `b` is immutably borrowed, we know its value, but cannot be removed.
opaque(d); // prevent `d` from being removed.
}
// Propagation through a borrowed reference.
{
let mut a = 5_usize;
let mut b = &mut a;
let d = &raw mut b;
let c = *b; // `b` is mutably borrowed, we cannot know its value.
opaque(d); // prevent `d` from being removed.
}
// Propagation through an escaping borrow.
{
let mut a = 7_usize;
let b = &mut a;
let c = *b;
opaque(b); // `b` escapes here, so we can only replace immutable borrow
}
// Propagation through a transitively escaping borrow.
{
let mut a = 7_usize;
let b1 = &mut a;
let c = *b1;
let b2 = b1;
let c2 = *b2;
let b3 = b2;
// `b3` escapes here, so we can only replace immutable borrow,
// for either `b`, `b2` or `b3`.
opaque(b3);
}
// Propagation a reborrow of an argument.
{
let a = &mut *single;
let b = *a; // This should be optimized as `*single`.
opaque(());
}
// Propagation a reborrow of a mutated argument.
{
let a = &mut *multiple;
multiple = &mut *single;
let b = *a; // This should not be optimized.
opaque(());
}
// Fixed-point propagation through a borrowed reference.
{
let mut a = 5_usize;
let b = &mut a;
let d = &b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
// Fixed-point propagation through a borrowed reference.
{
let mut a = 5_usize;
let mut b = &mut a;
let d = &mut b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
}
fn reference_propagation_const_ptr<T: Copy>(single: *const T, mut multiple: *const T) {
// Propagation through a reference.
unsafe {
let a = 5_usize;
let b = &raw const a; // This borrow is only used once.
let c = *b; // This should be optimized.
opaque(());
}
// Propagation through a two references.
unsafe {
let a = 5_usize;
let a2 = 7_usize;
let mut b = &raw const a;
b = &raw const a2;
// `b` is assigned twice, so we cannot propagate it.
let c = *b;
opaque(());
}
// Propagation through a borrowed reference.
unsafe {
let a = 5_usize;
let b = &raw const a;
let d = &b;
let c = *b; // `b` is immutably borrowed, we know its value, but cannot be removed.
opaque(d); // prevent `d` from being removed.
}
// Propagation through a borrowed reference.
unsafe {
let a = 5_usize;
let mut b = &raw const a;
let d = &raw mut b;
let c = *b; // `b` is mutably borrowed, we cannot know its value.
opaque(d); // prevent `d` from being removed.
}
// Propagation through an escaping borrow.
unsafe {
let a = 7_usize;
let b = &raw const a;
let c = *b;
opaque(b); // `b` escapes here, so we can only replace immutable borrow
}
// Propagation through a transitively escaping borrow.
unsafe {
let a = 7_usize;
let b1 = &raw const a;
let c = *b1;
let b2 = b1;
let c2 = *b2;
let b3 = b2;
// `b3` escapes here, so we can only replace immutable borrow,
// for either `b`, `b2` or `b3`.
opaque(b3);
}
// Propagation a reborrow of an argument.
unsafe {
let a = &raw const *single;
let b = *a; // This should be optimized as `*single`.
opaque(());
}
// Propagation a reborrow of a mutated argument.
unsafe {
let a = &raw const *multiple;
multiple = &raw const *single;
let b = *a; // This should not be optimized.
opaque(());
}
// Propagation through a reborrow.
unsafe {
let a = 13_usize;
let b = &raw const a;
let c = &raw const *b;
let e = *c;
opaque(());
}
// Fixed-point propagation through a borrowed reference.
unsafe {
let a = 5_usize;
let b = &raw const a;
let d = &b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
// Fixed-point propagation through a borrowed reference.
unsafe {
let a = 5_usize;
let mut b = &raw const a;
let d = &mut b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
}
fn reference_propagation_mut_ptr<T: Copy>(single: *mut T, mut multiple: *mut T) {
// Propagation through a reference.
unsafe {
let mut a = 5_usize;
let b = &raw mut a; // This borrow is only used once.
let c = *b; // This should be optimized.
opaque(());
}
// Propagation through a two references.
unsafe {
let mut a = 5_usize;
let mut a2 = 7_usize;
let mut b = &raw mut a;
b = &raw mut a2;
// `b` is assigned twice, so we cannot propagate it.
let c = *b;
opaque(());
}
// Propagation through a borrowed reference.
unsafe {
let mut a = 5_usize;
let b = &raw mut a;
let d = &b;
let c = *b; // `b` is immutably borrowed, we know its value, but cannot be removed.
opaque(d); // prevent `d` from being removed.
}
// Propagation through a borrowed reference.
unsafe {
let mut a = 5_usize;
let mut b = &raw mut a;
let d = &raw mut b;
let c = *b; // `b` is mutably borrowed, we cannot know its value.
opaque(d); // prevent `d` from being removed.
}
// Propagation through an escaping borrow.
unsafe {
let mut a = 7_usize;
let b = &raw mut a;
let c = *b;
opaque(b); // `b` escapes here, so we can only replace immutable borrow
}
// Propagation through a transitively escaping borrow.
unsafe {
let mut a = 7_usize;
let b1 = &raw mut a;
let c = *b1;
let b2 = b1;
let c2 = *b2;
let b3 = b2;
// `b3` escapes here, so we can only replace immutable borrow,
// for either `b`, `b2` or `b3`.
opaque(b3);
}
// Propagation a reborrow of an argument.
unsafe {
let a = &raw mut *single;
let b = *a; // This should be optimized as `*single`.
opaque(());
}
// Propagation a reborrow of a mutated argument.
unsafe {
let a = &raw mut *multiple;
multiple = &raw mut *single;
let b = *a; // This should not be optimized.
opaque(());
}
// Fixed-point propagation through a borrowed reference.
unsafe {
let mut a = 5_usize;
let b = &raw mut a;
let d = &b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
// Fixed-point propagation through a borrowed reference.
unsafe {
let mut a = 5_usize;
let mut b = &raw mut a;
let d = &mut b; // first round promotes debuginfo for `d`
let c = *b; // second round propagates this dereference
opaque(());
}
}
#[custom_mir(dialect = "runtime", phase = "post-cleanup")]
fn read_through_raw(x: &mut usize) -> usize {
use std::intrinsics::mir::*;
mir!(
let r1: &mut usize;
let r2: &mut usize;
let p1: *mut usize;
let p2: *mut usize;
{
r1 = &mut *x;
r2 = &mut *r1;
p1 = &raw mut *r1;
p2 = &raw mut *r2;
RET = *p1;
RET = *p2;
Return()
}
)
}
#[custom_mir(dialect = "runtime", phase = "post-cleanup")]
fn multiple_storage() {
use std::intrinsics::mir::*;
mir!(
let x: i32;
{
StorageLive(x);
x = 5;
let z = &x;
StorageDead(x);
StorageLive(x);
// As there are multiple `StorageLive` statements for `x`, we cannot know if this `z`'s
// pointer address is the address of `x`, so do nothing.
let y = *z;
Call(RET = opaque(y), retblock)
}
retblock = {
Return()
}
)
}
#[custom_mir(dialect = "runtime", phase = "post-cleanup")]
fn dominate_storage() {
use std::intrinsics::mir::*;
mir!(
let x: i32;
let r: &i32;
let c: i32;
let d: bool;
{ Goto(bb0) }
bb0 = {
x = 5;
r = &x;
Goto(bb1)
}
bb1 = {
let c = *r;
Call(RET = opaque(c), bb2)
}
bb2 = {
StorageDead(x);
StorageLive(x);
let d = true;
match d { false => bb2, _ => bb0 }
}
)
}
#[custom_mir(dialect = "runtime", phase = "post-cleanup")]
fn maybe_dead(m: bool) {
use std::intrinsics::mir::*;
mir!(
let x: i32;
let y: i32;
{
StorageLive(x);
StorageLive(y);
x = 5;
y = 5;
let a = &x;
let b = &mut y;
// As we don't replace `b` in `bb2`, we cannot replace it here either.
*b = 7;
// But this can still be replaced.
let u = *a;
match m { true => bb1, _ => bb2 }
}
bb1 = {
StorageDead(x);
StorageDead(y);
Call(RET = opaque(u), bb2)
}
bb2 = {
// As `x` may be `StorageDead`, `a` may be dangling, so we do nothing.
let z = *a;
Call(RET = opaque(z), bb3)
}
bb3 = {
// As `y` may be `StorageDead`, `b` may be dangling, so we do nothing.
// This implies that we also do not substitute `b` in `bb0`.
let t = *b;
Call(RET = opaque(t), retblock)
}
retblock = {
Return()
}
)
}
fn mut_raw_then_mut_shr() -> (i32, i32) {
let mut x = 2;
let xref = &mut x;
let xraw = &mut *xref as *mut _;
let xshr = &*xref;
// Verify that we completely replace with `x` in both cases.
let a = *xshr;
unsafe { *xraw = 4; }
(a, x)
}
fn unique_with_copies() {
let y = {
let mut a = 0;
let x = &raw mut a;
// `*y` is not replacable below, so we must not replace `*x`.
unsafe { opaque(*x) };
x
};
// But rewriting as `*x` is ok.
unsafe { opaque(*y) };
}
fn debuginfo() {
struct T(u8);
let ref_mut_u8 = &mut 5_u8;
let field = &T(0).0;
// Verify that we don't emit `&*` in debuginfo.
let reborrow = &*ref_mut_u8;
match Some(0) {
None => {}
Some(ref variant_field) => {}
}
// `constant_index_from_end` and `subslice` should not be promoted, as their value depends
// on the slice length.
if let [_, ref constant_index, subslice @ .., ref constant_index_from_end] = &[6; 10][..] {
}
let multiple_borrow = &&&mut T(6).0;
}
fn many_debuginfo() {
let a = 0;
// Verify that we do not ICE on deeply nested borrows.
let many_borrow =
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&a;
}
fn main() {
let mut x = 5_usize;
let mut y = 7_usize;
reference_propagation(&x, &y);
reference_propagation_mut(&mut x, &mut y);
reference_propagation_const_ptr(&raw const x, &raw const y);
reference_propagation_mut_ptr(&raw mut x, &raw mut y);
read_through_raw(&mut x);
multiple_storage();
dominate_storage();
maybe_dead(true);
mut_raw_then_mut_shr();
unique_with_copies();
debuginfo();
many_debuginfo();
}
// EMIT_MIR reference_prop.reference_propagation.ReferencePropagation.diff
// EMIT_MIR reference_prop.reference_propagation_mut.ReferencePropagation.diff
// EMIT_MIR reference_prop.reference_propagation_const_ptr.ReferencePropagation.diff
// EMIT_MIR reference_prop.reference_propagation_mut_ptr.ReferencePropagation.diff
// EMIT_MIR reference_prop.read_through_raw.ReferencePropagation.diff
// EMIT_MIR reference_prop.multiple_storage.ReferencePropagation.diff
// EMIT_MIR reference_prop.dominate_storage.ReferencePropagation.diff
// EMIT_MIR reference_prop.maybe_dead.ReferencePropagation.diff
// EMIT_MIR reference_prop.mut_raw_then_mut_shr.ReferencePropagation.diff
// EMIT_MIR reference_prop.unique_with_copies.ReferencePropagation.diff
// EMIT_MIR reference_prop.debuginfo.ReferencePropagation.diff