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79611d90b6
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.
119 lines
3.6 KiB
Diff
119 lines
3.6 KiB
Diff
- // MIR for `fn_pointers` before GVN
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+ // MIR for `fn_pointers` after GVN
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fn fn_pointers() -> () {
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let mut _0: ();
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let _1: fn(u8) -> u8;
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let _2: ();
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let mut _3: fn(u8) -> u8;
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let _5: ();
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let mut _6: fn(u8) -> u8;
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let mut _9: {closure@$DIR/gvn.rs:614:19: 614:21};
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let _10: ();
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let mut _11: fn();
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let mut _13: {closure@$DIR/gvn.rs:614:19: 614:21};
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let _14: ();
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let mut _15: fn();
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scope 1 {
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debug f => _1;
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let _4: fn(u8) -> u8;
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scope 2 {
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debug g => _4;
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let _7: {closure@$DIR/gvn.rs:614:19: 614:21};
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scope 3 {
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debug closure => _7;
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let _8: fn();
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scope 4 {
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debug cf => _8;
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let _12: fn();
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scope 5 {
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debug cg => _12;
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}
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}
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}
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}
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}
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bb0: {
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- StorageLive(_1);
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+ nop;
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_1 = identity::<u8> as fn(u8) -> u8 (PointerCoercion(ReifyFnPointer));
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StorageLive(_2);
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StorageLive(_3);
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_3 = copy _1;
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- _2 = opaque::<fn(u8) -> u8>(move _3) -> [return: bb1, unwind continue];
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+ _2 = opaque::<fn(u8) -> u8>(copy _1) -> [return: bb1, unwind continue];
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}
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bb1: {
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StorageDead(_3);
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StorageDead(_2);
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- StorageLive(_4);
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+ nop;
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_4 = identity::<u8> as fn(u8) -> u8 (PointerCoercion(ReifyFnPointer));
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StorageLive(_5);
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StorageLive(_6);
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_6 = copy _4;
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- _5 = opaque::<fn(u8) -> u8>(move _6) -> [return: bb2, unwind continue];
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+ _5 = opaque::<fn(u8) -> u8>(copy _4) -> [return: bb2, unwind continue];
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}
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bb2: {
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StorageDead(_6);
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StorageDead(_5);
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- StorageLive(_7);
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- _7 = {closure@$DIR/gvn.rs:614:19: 614:21};
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- StorageLive(_8);
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+ nop;
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+ _7 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
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+ nop;
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StorageLive(_9);
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- _9 = copy _7;
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- _8 = move _9 as fn() (PointerCoercion(ClosureFnPointer(Safe)));
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+ _9 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
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+ _8 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
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StorageDead(_9);
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StorageLive(_10);
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StorageLive(_11);
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_11 = copy _8;
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- _10 = opaque::<fn()>(move _11) -> [return: bb3, unwind continue];
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+ _10 = opaque::<fn()>(copy _8) -> [return: bb3, unwind continue];
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}
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bb3: {
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StorageDead(_11);
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StorageDead(_10);
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- StorageLive(_12);
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+ nop;
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StorageLive(_13);
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- _13 = copy _7;
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- _12 = move _13 as fn() (PointerCoercion(ClosureFnPointer(Safe)));
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+ _13 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
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+ _12 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
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StorageDead(_13);
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StorageLive(_14);
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StorageLive(_15);
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_15 = copy _12;
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- _14 = opaque::<fn()>(move _15) -> [return: bb4, unwind continue];
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+ _14 = opaque::<fn()>(copy _12) -> [return: bb4, unwind continue];
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}
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bb4: {
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StorageDead(_15);
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StorageDead(_14);
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_0 = const ();
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- StorageDead(_12);
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- StorageDead(_8);
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- StorageDead(_7);
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- StorageDead(_4);
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- StorageDead(_1);
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+ nop;
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+ nop;
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+ nop;
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+ nop;
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+ nop;
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return;
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}
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}
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