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