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rust/tests/mir-opt/gvn.rs
bors 79611d90b6 Auto merge of #122551 - RayMuir:copy_fmt, r=saethlin 
Added "copy" to Debug fmt for copy operands

In MIR's debug mode (--emit mir) the printing for Operands is slightly inconsistent.

The RValues - values on the right side of an Assign - are usually printed with their Operand when they are Places.

Example:
_2 = move _3

But for arguments, the operand is omitted.

_2 = _1

I propose a change be made, to display the place with the operand.

_2 = copy _1

Move and copy have different semantics, meaning this difference is important and helpful to the user. It also adds consistency to the pretty printing.

-- EDIT --

 Consider this example Rust program and its MIR output with the **updated pretty printer.**

This was generated with the arguments --emit mir --crate-type lib -Zmir-opt-level=0 (Otherwise, it's optimised away since it's a junk program).

```rust
fn main(foo: i32) {
    let v = 10;

    if v == 20 {
        foo;
    }
    else {
        v;
    }
}
```

```MIR
// WARNING: This output format is intended for human consumers only
// and is subject to change without notice. Knock yourself out.
fn main(_1: i32) -> () {
    debug foo => _1;
    let mut _0: ();
    let _2: i32;
    let mut _3: bool;
    let mut _4: i32;
    let _5: i32;
    let _6: i32;
    scope 1 {
        debug v => _2;
    }

    bb0: {
        StorageLive(_2);
        _2 = const 10_i32;
        StorageLive(_3);
        StorageLive(_4);
        _4 = copy _2;
        _3 = Eq(move _4, const 20_i32);
        switchInt(move _3) -> [0: bb2, otherwise: bb1];
    }

    bb1: {
        StorageDead(_4);
        StorageLive(_5);
        _5 = copy _1;
        StorageDead(_5);
        _0 = const ();
        goto -> bb3;
    }

    bb2: {
        StorageDead(_4);
        StorageLive(_6);
        _6 = copy _2;
        StorageDead(_6);
        _0 = const ();
        goto -> bb3;
    }

    bb3: {
        StorageDead(_3);
        StorageDead(_2);
        return;
    }
}
```

In this example program, we can see that when we move a place, it is preceded by "move". e.g. ``` _3 = Eq(move _4, const 20_i32);```. However, when we copy a place such as ```_5 = _1;```, it is not preceded by the operand in the original printout. I propose to change the print to include the copy ```_5 = copy _1``` as in this example.

Regarding the arguments part. When I originally submitted this PR, I was under the impression this only affected the print for arguments to a function, but actually, it affects anything that uses a copy. This is preferable anyway with regard to consistency. The PR is about making ```copy``` explicit.
2024-08-19 23:10:46 +00:00

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//@ test-mir-pass: GVN
//@ compile-flags: -Zdump-mir-exclude-alloc-bytes
// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
//@ only-64bit
#![feature(rustc_attrs)]
#![feature(custom_mir)]
#![feature(core_intrinsics)]
#![feature(freeze)]
#![allow(ambiguous_wide_pointer_comparisons)]
#![allow(unconditional_panic)]
#![allow(unused)]
use std::intrinsics::mir::*;
use std::marker::Freeze;
use std::mem::transmute;
struct S<T>(T);
fn subexpression_elimination(x: u64, y: u64, mut z: u64) {
// CHECK-LABEL: fn subexpression_elimination(
// CHECK: [[add:_.*]] = Add(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[add]])
opaque(x + y);
// CHECK: [[mul:_.*]] = Mul(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[mul]])
opaque(x * y);
// CHECK: [[sub:_.*]] = Sub(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[sub]])
opaque(x - y);
// CHECK: [[div:_.*]] = Div(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[div]])
opaque(x / y);
// CHECK: [[rem:_.*]] = Rem(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[rem]])
opaque(x % y);
// CHECK: [[and:_.*]] = BitAnd(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[and]])
opaque(x & y);
// CHECK: [[or:_.*]] = BitOr(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[or]])
opaque(x | y);
// CHECK: [[xor:_.*]] = BitXor(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[xor]])
opaque(x ^ y);
// CHECK: [[shl:_.*]] = Shl(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[shl]])
opaque(x << y);
// CHECK: [[shr:_.*]] = Shr(copy _1, copy _2);
// CHECK: opaque::<u64>(copy [[shr]])
opaque(x >> y);
// CHECK: [[int:_.*]] = copy _1 as u32 (IntToInt);
// CHECK: opaque::<u32>(copy [[int]])
opaque(x as u32);
// CHECK: [[float:_.*]] = copy _1 as f32 (IntToFloat);
// CHECK: opaque::<f32>(copy [[float]])
opaque(x as f32);
// CHECK: [[wrap:_.*]] = S::<u64>(copy _1);
// CHECK: opaque::<S<u64>>(copy [[wrap]])
opaque(S(x));
// CHECK: opaque::<u64>(copy _1)
opaque(S(x).0);
// Those are duplicates to substitute somehow.
// CHECK: opaque::<u64>(copy [[add]])
opaque(x + y);
// CHECK: opaque::<u64>(copy [[mul]])
opaque(x * y);
// CHECK: opaque::<u64>(copy [[sub]])
opaque(x - y);
// CHECK: opaque::<u64>(copy [[div]])
opaque(x / y);
// CHECK: opaque::<u64>(copy [[rem]])
opaque(x % y);
// CHECK: opaque::<u64>(copy [[and]])
opaque(x & y);
// CHECK: opaque::<u64>(copy [[or]])
opaque(x | y);
// CHECK: opaque::<u64>(copy [[xor]])
opaque(x ^ y);
// CHECK: opaque::<u64>(copy [[shl]])
opaque(x << y);
// CHECK: opaque::<u64>(copy [[shr]])
opaque(x >> y);
// CHECK: opaque::<u32>(copy [[int]])
opaque(x as u32);
// CHECK: opaque::<f32>(copy [[float]])
opaque(x as f32);
// CHECK: opaque::<S<u64>>(copy [[wrap]])
opaque(S(x));
// CHECK: opaque::<u64>(copy _1)
opaque(S(x).0);
// We can substitute through a complex expression.
// CHECK: [[compound:_.*]] = Sub(copy [[mul]], copy _2);
// CHECK: opaque::<u64>(copy [[compound]])
// CHECK: opaque::<u64>(copy [[compound]])
opaque((x * y) - y);
opaque((x * y) - y);
// We can substitute through an immutable reference too.
// CHECK: [[ref:_.*]] = &_3;
// CHECK: [[deref:_.*]] = copy (*[[ref]]);
// CHECK: [[addref:_.*]] = Add(copy [[deref]], copy _1);
// CHECK: opaque::<u64>(copy [[addref]])
// CHECK: opaque::<u64>(copy [[addref]])
let a = &z;
opaque(*a + x);
opaque(*a + x);
// But not through a mutable reference or a pointer.
// CHECK: [[mut:_.*]] = &mut _3;
// CHECK: [[addmut:_.*]] = Add(
// CHECK: opaque::<u64>(move [[addmut]])
// CHECK: [[addmut2:_.*]] = Add(
// CHECK: opaque::<u64>(move [[addmut2]])
let b = &mut z;
opaque(*b + x);
opaque(*b + x);
unsafe {
// CHECK: [[raw:_.*]] = &raw const _3;
// CHECK: [[addraw:_.*]] = Add(
// CHECK: opaque::<u64>(move [[addraw]])
// CHECK: [[addraw2:_.*]] = Add(
// CHECK: opaque::<u64>(move [[addraw2]])
let c = &raw const z;
opaque(*c + x);
opaque(*c + x);
// CHECK: [[ptr:_.*]] = &raw mut _3;
// CHECK: [[addptr:_.*]] = Add(
// CHECK: opaque::<u64>(move [[addptr]])
// CHECK: [[addptr2:_.*]] = Add(
// CHECK: opaque::<u64>(move [[addptr2]])
let d = &raw mut z;
opaque(*d + x);
opaque(*d + x);
}
// We can substitute again, but not with the earlier computations.
// Important: `e` is not `a`!
// CHECK: [[ref2:_.*]] = &_3;
// CHECK: [[deref2:_.*]] = copy (*[[ref2]]);
// CHECK: [[addref2:_.*]] = Add(copy [[deref2]], copy _1);
// CHECK: opaque::<u64>(copy [[addref2]])
// CHECK: opaque::<u64>(copy [[addref2]])
let e = &z;
opaque(*e + x);
opaque(*e + x);
}
fn wrap_unwrap<T: Copy>(x: T) -> T {
// CHECK-LABEL: fn wrap_unwrap(
// CHECK: [[some:_.*]] = Option::<T>::Some(copy _1);
// CHECK: switchInt(const 1_isize)
// CHECK: _0 = copy _1;
match Some(x) {
Some(y) => y,
None => panic!(),
}
}
fn repeated_index<T: Copy, const N: usize>(x: T, idx: usize) {
// CHECK-LABEL: fn repeated_index(
// CHECK: [[a:_.*]] = [copy _1; N];
let a = [x; N];
// CHECK: opaque::<T>(copy _1)
opaque(a[0]);
// CHECK: opaque::<T>(copy _1)
opaque(a[idx]);
}
fn unary(x: i64) {
// CHECK-LABEL: fn unary(
// CHECK: opaque::<i64>(copy _1)
opaque(--x); // This is `x`.
// CHECK: [[b:_.*]] = Lt(copy _1, const 13_i64);
// CHECK: opaque::<bool>(copy [[b]])
let b = x < 13;
opaque(!!b); // This is `b`.
// Both lines should test the same thing.
// CHECK: [[c:_.*]] = Ne(copy _1, const 15_i64);
// CHECK: opaque::<bool>(copy [[c]])
// CHECK: opaque::<bool>(copy [[c]])
opaque(x != 15);
opaque(!(x == 15));
// Both lines should test the same thing.
// CHECK: [[d:_.*]] = Eq(copy _1, const 35_i64);
// CHECK: opaque::<bool>(copy [[d]])
// CHECK: opaque::<bool>(copy [[d]])
opaque(x == 35);
opaque(!(x != 35));
}
/// Verify symbolic integer arithmetic simplifications.
fn arithmetic(x: u64) {
// CHECK-LABEL: fn arithmetic(
// CHECK: opaque::<u64>(copy _1)
opaque(x + 0);
// CHECK: opaque::<u64>(copy _1)
opaque(x - 0);
// CHECK: opaque::<u64>(const 0_u64)
opaque(x - x);
// CHECK: opaque::<u64>(const 0_u64)
opaque(x * 0);
// CHECK: opaque::<u64>(copy _1)
opaque(x * 1);
// CHECK: assert(!const true, "attempt to divide `{}` by zero",
// CHECK: [[div0:_.*]] = Div(copy _1, const 0_u64);
// CHECK: opaque::<u64>(move [[div0]])
opaque(x / 0);
// CHECK: opaque::<u64>(copy _1)
opaque(x / 1);
// CHECK: opaque::<u64>(const 0_u64)
opaque(0 / x);
// CHECK: [[odiv:_.*]] = Div(const 1_u64, copy _1);
// CHECK: opaque::<u64>(move [[odiv]])
opaque(1 / x);
// CHECK: assert(!const true, "attempt to calculate the remainder of `{}` with a divisor of zero"
// CHECK: [[rem0:_.*]] = Rem(copy _1, const 0_u64);
// CHECK: opaque::<u64>(move [[rem0]])
opaque(x % 0);
// CHECK: opaque::<u64>(const 0_u64)
opaque(x % 1);
// CHECK: opaque::<u64>(const 0_u64)
opaque(0 % x);
// CHECK: [[orem:_.*]] = Rem(const 1_u64, copy _1);
// CHECK: opaque::<u64>(move [[orem]])
opaque(1 % x);
// CHECK: opaque::<u64>(const 0_u64)
opaque(x & 0);
// CHECK: opaque::<u64>(copy _1)
opaque(x & u64::MAX);
// CHECK: opaque::<u64>(copy _1)
opaque(x | 0);
// CHECK: opaque::<u64>(const u64::MAX)
opaque(x | u64::MAX);
// CHECK: opaque::<u64>(copy _1)
opaque(x ^ 0);
// CHECK: opaque::<u64>(const 0_u64)
opaque(x ^ x);
// CHECK: opaque::<u64>(copy _1)
opaque(x >> 0);
// CHECK: opaque::<u64>(copy _1)
opaque(x << 0);
}
fn comparison(x: u64, y: u64) {
// CHECK-LABEL: fn comparison(
// CHECK: opaque::<bool>(const true)
opaque(x == x);
// CHECK: opaque::<bool>(const false)
opaque(x != x);
// CHECK: [[eqxy:_.*]] = Eq(copy _1, copy _2);
// CHECK: opaque::<bool>(move [[eqxy]])
opaque(x == y);
// CHECK: [[nexy:_.*]] = Ne(copy _1, copy _2);
// CHECK: opaque::<bool>(move [[nexy]])
opaque(x != y);
}
/// Verify symbolic integer arithmetic simplifications on checked ops.
#[rustc_inherit_overflow_checks]
fn arithmetic_checked(x: u64) {
// CHECK-LABEL: fn arithmetic_checked(
// CHECK: assert(!const false,
// CHECK: opaque::<u64>(copy _1)
opaque(x + 0);
// CHECK: assert(!const false,
// CHECK: opaque::<u64>(copy _1)
opaque(x - 0);
// CHECK: assert(!const false,
// CHECK: opaque::<u64>(const 0_u64)
opaque(x - x);
// CHECK: assert(!const false,
// CHECK: opaque::<u64>(const 0_u64)
opaque(x * 0);
// CHECK: assert(!const false,
// CHECK: opaque::<u64>(copy _1)
opaque(x * 1);
}
/// Verify that we do not apply arithmetic simplifications on floats.
fn arithmetic_float(x: f64) {
// CHECK-LABEL: fn arithmetic_float(
// CHECK: [[add:_.*]] = Add(copy _1, const 0f64);
// CHECK: opaque::<f64>(move [[add]])
opaque(x + 0.);
// CHECK: [[sub:_.*]] = Sub(copy _1, const 0f64);
// CHECK: opaque::<f64>(move [[sub]])
opaque(x - 0.);
// CHECK: [[mul:_.*]] = Mul(copy _1, const 0f64);
// CHECK: opaque::<f64>(move [[mul]])
opaque(x * 0.);
// CHECK: [[div0:_.*]] = Div(copy _1, const 0f64);
// CHECK: opaque::<f64>(move [[div0]])
opaque(x / 0.);
// CHECK: [[zdiv:_.*]] = Div(const 0f64, copy _1);
// CHECK: opaque::<f64>(move [[zdiv]])
opaque(0. / x);
// CHECK: [[rem0:_.*]] = Rem(copy _1, const 0f64);
// CHECK: opaque::<f64>(move [[rem0]])
opaque(x % 0.);
// CHECK: [[zrem:_.*]] = Rem(const 0f64, copy _1);
// CHECK: opaque::<f64>(move [[zrem]])
opaque(0. % x);
// Those are not simplifiable to `true`/`false`, thanks to NaNs.
// CHECK: [[eq:_.*]] = Eq(copy _1, copy _1);
// CHECK: opaque::<bool>(move [[eq]])
opaque(x == x);
// CHECK: [[ne:_.*]] = Ne(copy _1, copy _1);
// CHECK: opaque::<bool>(move [[ne]])
opaque(x != x);
}
fn cast() {
// CHECK-LABEL: fn cast(
let i = 1_i64;
let u = 1_u64;
let f = 1_f64;
// CHECK: opaque::<u8>(const 1_u8)
opaque(i as u8);
// CHECK: opaque::<u16>(const 1_u16)
opaque(i as u16);
// CHECK: opaque::<u32>(const 1_u32)
opaque(i as u32);
// CHECK: opaque::<u64>(const 1_u64)
opaque(i as u64);
// CHECK: opaque::<i8>(const 1_i8)
opaque(i as i8);
// CHECK: opaque::<i16>(const 1_i16)
opaque(i as i16);
// CHECK: opaque::<i32>(const 1_i32)
opaque(i as i32);
// CHECK: opaque::<i64>(const 1_i64)
opaque(i as i64);
// CHECK: opaque::<f32>(const 1f32)
opaque(i as f32);
// CHECK: opaque::<f64>(const 1f64)
opaque(i as f64);
// CHECK: opaque::<u8>(const 1_u8)
opaque(u as u8);
// CHECK: opaque::<u16>(const 1_u16)
opaque(u as u16);
// CHECK: opaque::<u32>(const 1_u32)
opaque(u as u32);
// CHECK: opaque::<u64>(const 1_u64)
opaque(u as u64);
// CHECK: opaque::<i8>(const 1_i8)
opaque(u as i8);
// CHECK: opaque::<i16>(const 1_i16)
opaque(u as i16);
// CHECK: opaque::<i32>(const 1_i32)
opaque(u as i32);
// CHECK: opaque::<i64>(const 1_i64)
opaque(u as i64);
// CHECK: opaque::<f32>(const 1f32)
opaque(u as f32);
// CHECK: opaque::<f64>(const 1f64)
opaque(u as f64);
// CHECK: opaque::<u8>(const 1_u8)
opaque(f as u8);
// CHECK: opaque::<u16>(const 1_u16)
opaque(f as u16);
// CHECK: opaque::<u32>(const 1_u32)
opaque(f as u32);
// CHECK: opaque::<u64>(const 1_u64)
opaque(f as u64);
// CHECK: opaque::<i8>(const 1_i8)
opaque(f as i8);
// CHECK: opaque::<i16>(const 1_i16)
opaque(f as i16);
// CHECK: opaque::<i32>(const 1_i32)
opaque(f as i32);
// CHECK: opaque::<i64>(const 1_i64)
opaque(f as i64);
// CHECK: opaque::<f32>(const 1f32)
opaque(f as f32);
// CHECK: opaque::<f64>(const 1f64)
opaque(f as f64);
}
fn multiple_branches(t: bool, x: u8, y: u8) {
// CHECK-LABEL: fn multiple_branches(
// CHECK: switchInt(copy _1) -> [0: [[bbf:bb.*]], otherwise: [[bbt:bb.*]]];
if t {
// CHECK: [[bbt]]: {
// CHECK: [[a:_.*]] = Add(copy _2, copy _3);
// CHECK: opaque::<u8>(copy [[a]])
// CHECK: opaque::<u8>(copy [[a]])
// CHECK: goto -> [[bbc:bb.*]];
opaque(x + y);
opaque(x + y);
} else {
// CHECK: [[bbf]]: {
// CHECK: [[b:_.*]] = Add(copy _2, copy _3);
// CHECK: opaque::<u8>(copy [[b]])
// CHECK: opaque::<u8>(copy [[b]])
// CHECK: goto -> [[bbc:bb.*]];
opaque(x + y);
opaque(x + y);
}
// Neither `a` nor `b` dominate `c`, so we cannot reuse any of them.
// CHECK: [[bbc]]: {
// CHECK: [[c:_.*]] = Add(copy _2, copy _3);
// CHECK: opaque::<u8>(copy [[c]])
opaque(x + y);
// `c` dominates both calls, so we can reuse it.
if t {
// CHECK: opaque::<u8>(copy [[c]])
opaque(x + y);
} else {
// CHECK: opaque::<u8>(copy [[c]])
opaque(x + y);
}
}
/// Verify that we do not reuse a `&raw? mut?` rvalue.
fn references(mut x: impl Sized) {
// CHECK-LABEL: fn references(
// CHECK: [[ref1:_.*]] = &_1;
// CHECK: opaque::<&impl Sized>(move [[ref1]])
opaque(&x);
// CHECK: [[ref2:_.*]] = &_1;
// CHECK: opaque::<&impl Sized>(move [[ref2]])
opaque(&x);
// CHECK: [[ref3:_.*]] = &mut _1;
// CHECK: opaque::<&mut impl Sized>(move [[ref3]])
opaque(&mut x);
// CHECK: [[ref4:_.*]] = &mut _1;
// CHECK: opaque::<&mut impl Sized>(move [[ref4]])
opaque(&mut x);
// CHECK: [[ref5:_.*]] = &raw const _1;
// CHECK: opaque::<*const impl Sized>(move [[ref5]])
opaque(&raw const x);
// CHECK: [[ref6:_.*]] = &raw const _1;
// CHECK: opaque::<*const impl Sized>(move [[ref6]])
opaque(&raw const x);
// CHECK: [[ref7:_.*]] = &raw mut _1;
// CHECK: opaque::<*mut impl Sized>(move [[ref7]])
opaque(&raw mut x);
// CHECK: [[ref8:_.*]] = &raw mut _1;
// CHECK: opaque::<*mut impl Sized>(move [[ref8]])
opaque(&raw mut x);
let r = &mut x;
let s = S(r).0; // Obfuscate `r`. Following lines should still reborrow `r`.
// CHECK: [[ref9:_.*]] = &mut _1;
// CHECK: [[ref10:_.*]] = &(*[[ref9]]);
// CHECK: opaque::<&impl Sized>(move [[ref10]])
opaque(&*s);
// CHECK: [[ref11:_.*]] = &mut (*[[ref9]]);
// CHECK: opaque::<&mut impl Sized>(move [[ref11]])
opaque(&mut *s);
// CHECK: [[ref12:_.*]] = &raw const (*[[ref9]]);
// CHECK: opaque::<*const impl Sized>(move [[ref12]])
opaque(&raw const *s);
// CHECK: [[ref12:_.*]] = &raw mut (*[[ref9]]);
// CHECK: opaque::<*mut impl Sized>(move [[ref12]])
opaque(&raw mut *s);
}
fn dereferences(t: &mut u32, u: &impl Copy, s: &S<u32>) {
// CHECK-LABEL: fn dereferences(
// Do not reuse dereferences of `&mut`.
// CHECK: [[st1:_.*]] = copy (*_1);
// CHECK: opaque::<u32>(move [[st1]])
// CHECK: [[st2:_.*]] = copy (*_1);
// CHECK: opaque::<u32>(move [[st2]])
opaque(*t);
opaque(*t);
// Do not reuse dereferences of `*const`.
// CHECK: [[raw:_.*]] = &raw const (*_1);
// CHECK: [[st3:_.*]] = copy (*[[raw]]);
// CHECK: opaque::<u32>(move [[st3]])
// CHECK: [[st4:_.*]] = copy (*[[raw]]);
// CHECK: opaque::<u32>(move [[st4]])
let z = &raw const *t;
unsafe { opaque(*z) };
unsafe { opaque(*z) };
// Do not reuse dereferences of `*mut`.
// CHECK: [[ptr:_.*]] = &raw mut (*_1);
// CHECK: [[st5:_.*]] = copy (*[[ptr]]);
// CHECK: opaque::<u32>(move [[st5]])
// CHECK: [[st6:_.*]] = copy (*[[ptr]]);
// CHECK: opaque::<u32>(move [[st6]])
let z = &raw mut *t;
unsafe { opaque(*z) };
unsafe { opaque(*z) };
// We can reuse dereferences of `&Freeze`.
// CHECK: [[ref:_.*]] = &(*_1);
// CHECK: [[st7:_.*]] = copy (*[[ref]]);
// CHECK: opaque::<u32>(copy [[st7]])
// CHECK: opaque::<u32>(copy [[st7]])
let z = &*t;
opaque(*z);
opaque(*z);
// But not in reborrows.
// CHECK: [[reborrow:_.*]] = &(*[[ref]]);
// CHECK: opaque::<&u32>(move [[reborrow]])
opaque(&*z);
// `*u` is not Freeze, so we cannot reuse.
// CHECK: [[st8:_.*]] = copy (*_2);
// CHECK: opaque::<impl Copy>(move [[st8]])
// CHECK: [[st9:_.*]] = copy (*_2);
// CHECK: opaque::<impl Copy>(move [[st9]])
opaque(*u);
opaque(*u);
// `*s` is not Copy, but `(*s).0` is, so we can reuse.
// CHECK: [[st10:_.*]] = copy ((*_3).0: u32);
// CHECK: opaque::<u32>(copy [[st10]])
// CHECK: opaque::<u32>(copy [[st10]])
opaque(s.0);
opaque(s.0);
}
fn slices() {
// CHECK-LABEL: fn slices(
// CHECK: {{_.*}} = const "
// CHECK-NOT: {{_.*}} = const "
let s = "my favourite slice"; // This is a `Const::Slice` in MIR.
opaque(s);
let t = s; // This should be the same pointer, so cannot be a `Const::Slice`.
opaque(t);
assert_eq!(s.as_ptr(), t.as_ptr());
let u = unsafe { transmute::<&str, &[u8]>(s) };
opaque(u);
assert_eq!(s.as_ptr(), u.as_ptr());
}
#[custom_mir(dialect = "analysis")]
fn duplicate_slice() -> (bool, bool) {
// CHECK-LABEL: fn duplicate_slice(
mir! {
let au: u128;
let bu: u128;
let cu: u128;
let du: u128;
let c: &str;
let d: &str;
{
// CHECK: [[a:_.*]] = (const "a",);
// CHECK: [[au:_.*]] = copy ([[a]].0: &str) as u128 (Transmute);
let a = ("a",);
Call(au = transmute::<_, u128>(a.0), ReturnTo(bb1), UnwindContinue())
}
bb1 = {
// CHECK: [[c:_.*]] = identity::<&str>(copy ([[a]].0: &str))
Call(c = identity(a.0), ReturnTo(bb2), UnwindContinue())
}
bb2 = {
// CHECK: [[cu:_.*]] = copy [[c]] as u128 (Transmute);
Call(cu = transmute::<_, u128>(c), ReturnTo(bb3), UnwindContinue())
}
bb3 = {
// This slice is different from `a.0`. Hence `bu` is not `au`.
// CHECK: [[b:_.*]] = const "a";
// CHECK: [[bu:_.*]] = copy [[b]] as u128 (Transmute);
let b = "a";
Call(bu = transmute::<_, u128>(b), ReturnTo(bb4), UnwindContinue())
}
bb4 = {
// This returns a copy of `b`, which is not `a`.
// CHECK: [[d:_.*]] = identity::<&str>(copy [[b]])
Call(d = identity(b), ReturnTo(bb5), UnwindContinue())
}
bb5 = {
// CHECK: [[du:_.*]] = copy [[d]] as u128 (Transmute);
Call(du = transmute::<_, u128>(d), ReturnTo(bb6), UnwindContinue())
}
bb6 = {
// `direct` must not fold to `true`, as `indirect` will not.
// CHECK: = Eq(copy [[au]], copy [[bu]]);
// CHECK: = Eq(copy [[cu]], copy [[du]]);
let direct = au == bu;
let indirect = cu == du;
RET = (direct, indirect);
Return()
}
}
}
fn repeat() {
// CHECK-LABEL: fn repeat(
// CHECK: = [const 5_i32; 10];
let val = 5;
let array = [val, val, val, val, val, val, val, val, val, val];
}
/// Verify that we do not merge fn pointers created by casts.
fn fn_pointers() {
// CHECK-LABEL: fn fn_pointers(
// CHECK: [[f:_.*]] = identity::<u8> as fn(u8) -> u8 (PointerCoercion(ReifyFnPointer
// CHECK: opaque::<fn(u8) -> u8>(copy [[f]])
let f = identity as fn(u8) -> u8;
opaque(f);
// CHECK: [[g:_.*]] = identity::<u8> as fn(u8) -> u8 (PointerCoercion(ReifyFnPointer
// CHECK: opaque::<fn(u8) -> u8>(copy [[g]])
let g = identity as fn(u8) -> u8;
opaque(g);
// CHECK: [[cf:_.*]] = const {{.*}} as fn() (PointerCoercion(ClosureFnPointer
// CHECK: opaque::<fn()>(copy [[cf]])
let closure = || {};
let cf = closure as fn();
opaque(cf);
// CHECK: [[cg:_.*]] = const {{.*}} as fn() (PointerCoercion(ClosureFnPointer
// CHECK: opaque::<fn()>(copy [[cg]])
let cg = closure as fn();
opaque(cg);
}
/// Verify that we do not create a `ConstValue::Indirect` backed by a static's AllocId.
#[custom_mir(dialect = "analysis")]
fn indirect_static() {
static A: Option<u8> = None;
mir! {
{
let ptr = Static(A);
let out = Field::<u8>(Variant(*ptr, 1), 0);
Return()
}
}
}
/// Verify that having constant index `u64::MAX` does not yield to an overflow in rustc.
fn constant_index_overflow<T: Copy>(x: &[T]) {
// CHECK-LABEL: fn constant_index_overflow(
// CHECK: debug a => [[a:_.*]];
// CHECK: debug b => [[b:_.*]];
// CHECK: [[a]] = const usize::MAX;
// CHECK-NOT: = (*_1)[{{.*}} of 0];
// CHECK: [[b]] = copy (*_1)[[[a]]];
// CHECK-NOT: = (*_1)[{{.*}} of 0];
// CHECK: [[b]] = copy (*_1)[0 of 1];
// CHECK-NOT: = (*_1)[{{.*}} of 0];
let a = u64::MAX as usize;
let b = if a < x.len() { x[a] } else { x[0] };
opaque(b)
}
/// Check that we do not attempt to simplify anything when there is provenance.
fn wide_ptr_provenance() {
// CHECK-LABEL: fn wide_ptr_provenance(
let a: *const dyn Send = &1 as &dyn Send;
let b: *const dyn Send = &1 as &dyn Send;
// CHECK: [[eqp:_.*]] = Eq(copy [[a:_.*]], copy [[b:_.*]]);
// CHECK: opaque::<bool>(move [[eqp]])
opaque(a == b);
// CHECK: [[nep:_.*]] = Ne(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[nep]])
opaque(a != b);
// CHECK: [[ltp:_.*]] = Lt(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[ltp]])
opaque(a < b);
// CHECK: [[lep:_.*]] = Le(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[lep]])
opaque(a <= b);
// CHECK: [[gtp:_.*]] = Gt(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[gtp]])
opaque(a > b);
// CHECK: [[gep:_.*]] = Ge(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[gep]])
opaque(a >= b);
}
/// Both pointers come form the same allocation, so we could probably fold the comparisons.
fn wide_ptr_same_provenance() {
// CHECK-LABEL: fn wide_ptr_same_provenance(
let slice = &[1, 2];
let a: *const dyn Send = &slice[0] as &dyn Send;
let b: *const dyn Send = &slice[1] as &dyn Send;
// CHECK: [[eqp:_.*]] = Eq(copy [[a:_.*]], copy [[b:_.*]]);
// CHECK: opaque::<bool>(move [[eqp]])
opaque(a == b);
// CHECK: [[nep:_.*]] = Ne(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[nep]])
opaque(a != b);
// CHECK: [[ltp:_.*]] = Lt(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[ltp]])
opaque(a < b);
// CHECK: [[lep:_.*]] = Le(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[lep]])
opaque(a <= b);
// CHECK: [[gtp:_.*]] = Gt(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[gtp]])
opaque(a > b);
// CHECK: [[gep:_.*]] = Ge(copy [[a]], copy [[b]]);
// CHECK: opaque::<bool>(move [[gep]])
opaque(a >= b);
}
/// Check that we do simplify when there is no provenance, and do not ICE.
fn wide_ptr_integer() {
// CHECK-LABEL: fn wide_ptr_integer(
// CHECK: debug a => [[a:_.*]];
// CHECK: debug b => [[b:_.*]];
let a: *const [u8] = unsafe { transmute((1usize, 1usize)) };
let b: *const [u8] = unsafe { transmute((1usize, 2usize)) };
// CHECK: opaque::<bool>(const false)
opaque(a == b);
// CHECK: opaque::<bool>(const true)
opaque(a != b);
// CHECK: opaque::<bool>(const true)
opaque(a < b);
// CHECK: opaque::<bool>(const true)
opaque(a <= b);
// CHECK: opaque::<bool>(const false)
opaque(a > b);
// CHECK: opaque::<bool>(const false)
opaque(a >= b);
}
#[custom_mir(dialect = "analysis", phase = "post-cleanup")]
fn borrowed<T: Copy + Freeze>(x: T) {
// CHECK-LABEL: fn borrowed(
// CHECK: bb0: {
// CHECK-NEXT: _2 = copy _1;
// CHECK-NEXT: _3 = &_1;
// CHECK-NEXT: _0 = opaque::<&T>(copy _3)
// CHECK: bb1: {
// CHECK-NEXT: _0 = opaque::<T>(copy _1)
// CHECK: bb2: {
// CHECK-NEXT: _0 = opaque::<T>(copy _1)
mir! {
{
let a = x;
let r1 = &x;
Call(RET = opaque(r1), ReturnTo(next), UnwindContinue())
}
next = {
Call(RET = opaque(a), ReturnTo(deref), UnwindContinue())
}
deref = {
Call(RET = opaque(*r1), ReturnTo(ret), UnwindContinue())
}
ret = {
Return()
}
}
}
/// Generic type `T` is not known to be `Freeze`, so shared borrows may be mutable.
#[custom_mir(dialect = "analysis", phase = "post-cleanup")]
fn non_freeze<T: Copy>(x: T) {
// CHECK-LABEL: fn non_freeze(
// CHECK: bb0: {
// CHECK-NEXT: _2 = copy _1;
// CHECK-NEXT: _3 = &_1;
// CHECK-NEXT: _0 = opaque::<&T>(copy _3)
// CHECK: bb1: {
// CHECK-NEXT: _0 = opaque::<T>(copy _2)
// CHECK: bb2: {
// CHECK-NEXT: _0 = opaque::<T>(copy (*_3))
mir! {
{
let a = x;
let r1 = &x;
Call(RET = opaque(r1), ReturnTo(next), UnwindContinue())
}
next = {
Call(RET = opaque(a), ReturnTo(deref), UnwindContinue())
}
deref = {
Call(RET = opaque(*r1), ReturnTo(ret), UnwindContinue())
}
ret = {
Return()
}
}
}
// Check that we can const-prop into `from_raw_parts`
fn slice_const_length(x: &[i32]) -> *const [i32] {
// CHECK-LABEL: fn slice_const_length(
// CHECK: _0 = *const [i32] from (copy {{_[0-9]+}}, const 123_usize);
let ptr = x.as_ptr();
let len = 123;
std::intrinsics::aggregate_raw_ptr(ptr, len)
}
fn meta_of_ref_to_slice(x: *const i32) -> usize {
// CHECK-LABEL: fn meta_of_ref_to_slice
// CHECK: _0 = const 1_usize
let ptr: *const [i32] = std::intrinsics::aggregate_raw_ptr(x, 1);
std::intrinsics::ptr_metadata(ptr)
}
fn slice_from_raw_parts_as_ptr(x: *const u16, n: usize) -> (*const u16, *const f32) {
// CHECK-LABEL: fn slice_from_raw_parts_as_ptr
// CHECK: _8 = copy _1 as *const f32 (PtrToPtr);
// CHECK: _0 = (copy _1, move _8);
let ptr: *const [u16] = std::intrinsics::aggregate_raw_ptr(x, n);
(ptr as *const u16, ptr as *const f32)
}
fn casts_before_aggregate_raw_ptr(x: *const u32) -> *const [u8] {
// CHECK-LABEL: fn casts_before_aggregate_raw_ptr
// CHECK: _0 = *const [u8] from (copy _1, const 4_usize);
let x = x as *const [u8; 4];
let x = x as *const u8;
let x = x as *const ();
std::intrinsics::aggregate_raw_ptr(x, 4)
}
fn manual_slice_mut_len(x: &mut [i32]) -> usize {
// CHECK-LABEL: fn manual_slice_mut_len
// CHECK: _0 = PtrMetadata(copy _1);
let x: *mut [i32] = x;
let x: *const [i32] = x;
std::intrinsics::ptr_metadata(x)
}
// `.len()` on arrays ends up being something like this
fn array_len(x: &mut [i32; 42]) -> usize {
// CHECK-LABEL: fn array_len
// CHECK: _0 = const 42_usize;
let x: &[i32] = x;
std::intrinsics::ptr_metadata(x)
}
#[custom_mir(dialect = "runtime")]
fn generic_cast_metadata<T, A: ?Sized, B: ?Sized>(ps: *const [T], pa: *const A, pb: *const B) {
// CHECK-LABEL: fn generic_cast_metadata
mir! {
{
// These tests check that we correctly do or don't elide casts
// when the pointee metadata do or don't match, respectively.
// Metadata usize -> (), do not optimize.
// CHECK: [[T:_.+]] = copy _1 as
// CHECK-NEXT: PtrMetadata(copy [[T]])
let t1 = CastPtrToPtr::<_, *const T>(ps);
let m1 = PtrMetadata(t1);
// `(&A, [T])` has `usize` metadata, same as `[T]`, yes optimize.
// CHECK: [[T:_.+]] = copy _1 as
// CHECK-NEXT: PtrMetadata(copy _1)
let t2 = CastPtrToPtr::<_, *const (&A, [T])>(ps);
let m2 = PtrMetadata(t2);
// Tail `A` and tail `B`, do not optimize.
// CHECK: [[T:_.+]] = copy _2 as
// CHECK-NEXT: PtrMetadata(copy [[T]])
let t3 = CastPtrToPtr::<_, *const (T, B)>(pa);
let m3 = PtrMetadata(t3);
// Both have tail `A`, yes optimize.
// CHECK: [[T:_.+]] = copy _2 as
// CHECK-NEXT: PtrMetadata(copy _2)
let t4 = CastPtrToPtr::<_, *const (T, A)>(pa);
let m4 = PtrMetadata(t4);
// Tail `B` and tail `A`, do not optimize.
// CHECK: [[T:_.+]] = copy _3 as
// CHECK-NEXT: PtrMetadata(copy [[T]])
let t5 = CastPtrToPtr::<_, *mut A>(pb);
let m5 = PtrMetadata(t5);
// Both have tail `B`, yes optimize.
// CHECK: [[T:_.+]] = copy _3 as
// CHECK-NEXT: PtrMetadata(copy _3)
let t6 = CastPtrToPtr::<_, *mut B>(pb);
let m6 = PtrMetadata(t6);
Return()
}
}
}
fn cast_pointer_eq(p1: *mut u8, p2: *mut u32, p3: *mut u32, p4: *mut [u32]) {
// CHECK-LABEL: fn cast_pointer_eq
// CHECK: debug p1 => [[P1:_1]];
// CHECK: debug p2 => [[P2:_2]];
// CHECK: debug p3 => [[P3:_3]];
// CHECK: debug p4 => [[P4:_4]];
// CHECK: [[M1:_.+]] = copy [[P1]] as *const u32 (PtrToPtr);
// CHECK: [[M2:_.+]] = copy [[P2]] as *const u32 (PtrToPtr);
// CHECK: [[M3:_.+]] = copy [[P3]] as *const u32 (PtrToPtr);
// CHECK: [[M4:_.+]] = copy [[P4]] as *const u32 (PtrToPtr);
let m1 = p1 as *const u32;
let m2 = p2 as *const u32;
let m3 = p3 as *const u32;
let m4 = p4 as *const u32;
// CHECK-NOT: Eq
// CHECK: Eq(copy [[M1]], copy [[M2]])
// CHECK-NOT: Eq
// CHECK: Eq(copy [[P2]], copy [[P3]])
// CHECK-NOT: Eq
// CHECK: Eq(copy [[M3]], copy [[M4]])
// CHECK-NOT: Eq
let eq_different_thing = m1 == m2;
let eq_optimize = m2 == m3;
let eq_thin_fat = m3 == m4;
// CHECK: _0 = const ();
}
// Transmuting can skip a pointer cast so long as it wasn't a fat-to-thin cast.
unsafe fn cast_pointer_then_transmute(thin: *mut u32, fat: *mut [u8]) {
// CHECK-LABEL: fn cast_pointer_then_transmute
// CHECK: [[UNUSED:_.+]] = copy _1 as *const () (PtrToPtr);
// CHECK: = copy _1 as usize (Transmute);
let thin_addr: usize = std::intrinsics::transmute(thin as *const ());
// CHECK: [[TEMP2:_.+]] = copy _2 as *const () (PtrToPtr);
// CHECK: = move [[TEMP2]] as usize (Transmute);
let fat_addr: usize = std::intrinsics::transmute(fat as *const ());
}
#[custom_mir(dialect = "analysis")]
fn remove_casts_must_change_both_sides(mut_a: &*mut u8, mut_b: *mut u8) -> bool {
// CHECK-LABEL: fn remove_casts_must_change_both_sides(
mir! {
// We'd like to remove these casts, but we can't change *both* of them
// to be locals, so make sure we don't change one without the other, as
// that would be a type error.
{
// CHECK: [[A:_.+]] = copy (*_1) as *const u8 (PtrToPtr);
let a = *mut_a as *const u8;
// CHECK: [[B:_.+]] = copy _2 as *const u8 (PtrToPtr);
let b = mut_b as *const u8;
// CHECK: _0 = Eq(copy [[A]], copy [[B]]);
RET = a == b;
Return()
}
}
}
fn main() {
subexpression_elimination(2, 4, 5);
wrap_unwrap(5);
repeated_index::<u32, 7>(5, 3);
unary(i64::MIN);
arithmetic(5);
comparison(5, 6);
arithmetic_checked(5);
arithmetic_float(5.);
cast();
multiple_branches(true, 5, 9);
references(5);
dereferences(&mut 5, &6, &S(7));
slices();
let (direct, indirect) = duplicate_slice();
assert_eq!(direct, indirect);
repeat();
fn_pointers();
indirect_static();
constant_index_overflow(&[5, 3]);
wide_ptr_provenance();
wide_ptr_integer();
borrowed(5);
non_freeze(5);
slice_const_length(&[1]);
meta_of_ref_to_slice(&42);
slice_from_raw_parts_as_ptr(&123, 456);
}
#[inline(never)]
fn opaque(_: impl Sized) {}
#[inline(never)]
fn identity<T>(x: T) -> T {
x
}
// EMIT_MIR gvn.subexpression_elimination.GVN.diff
// EMIT_MIR gvn.wrap_unwrap.GVN.diff
// EMIT_MIR gvn.repeated_index.GVN.diff
// EMIT_MIR gvn.unary.GVN.diff
// EMIT_MIR gvn.arithmetic.GVN.diff
// EMIT_MIR gvn.comparison.GVN.diff
// EMIT_MIR gvn.arithmetic_checked.GVN.diff
// EMIT_MIR gvn.arithmetic_float.GVN.diff
// EMIT_MIR gvn.cast.GVN.diff
// EMIT_MIR gvn.multiple_branches.GVN.diff
// EMIT_MIR gvn.references.GVN.diff
// EMIT_MIR gvn.dereferences.GVN.diff
// EMIT_MIR gvn.slices.GVN.diff
// EMIT_MIR gvn.duplicate_slice.GVN.diff
// EMIT_MIR gvn.repeat.GVN.diff
// EMIT_MIR gvn.fn_pointers.GVN.diff
// EMIT_MIR gvn.indirect_static.GVN.diff
// EMIT_MIR gvn.constant_index_overflow.GVN.diff
// EMIT_MIR gvn.wide_ptr_provenance.GVN.diff
// EMIT_MIR gvn.wide_ptr_same_provenance.GVN.diff
// EMIT_MIR gvn.wide_ptr_integer.GVN.diff
// EMIT_MIR gvn.borrowed.GVN.diff
// EMIT_MIR gvn.non_freeze.GVN.diff
// EMIT_MIR gvn.slice_const_length.GVN.diff
// EMIT_MIR gvn.meta_of_ref_to_slice.GVN.diff
// EMIT_MIR gvn.slice_from_raw_parts_as_ptr.GVN.diff
// EMIT_MIR gvn.casts_before_aggregate_raw_ptr.GVN.diff
// EMIT_MIR gvn.manual_slice_mut_len.GVN.diff
// EMIT_MIR gvn.array_len.GVN.diff
// EMIT_MIR gvn.generic_cast_metadata.GVN.diff
// EMIT_MIR gvn.cast_pointer_eq.GVN.diff
// EMIT_MIR gvn.cast_pointer_then_transmute.GVN.diff
// EMIT_MIR gvn.remove_casts_must_change_both_sides.GVN.diff
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