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.
41 lines
917 B
Rust
41 lines
917 B
Rust
//@ test-mir-pass: GVN
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// Check that we do not propagate past an indirect mutation.
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// EMIT_MIR indirect_mutation.foo.GVN.diff
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fn foo() {
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// CHECK-LABEL: fn foo(
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// CHECK: debug u => _1;
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// CHECK: debug y => _3;
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// CHECK: _1 = const (1_i32,);
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// CHECK: _2 = &mut (_1.0: i32);
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// CHECK: (*_2) = const 5_i32;
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// CHECK: _4 = copy (_1.0: i32);
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// CHECK: _3 = Eq(move _4, const 5_i32);
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let mut u = (1,);
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*&mut u.0 = 5;
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let y = { u.0 } == 5;
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}
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// EMIT_MIR indirect_mutation.bar.GVN.diff
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fn bar() {
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// CHECK-LABEL: fn bar(
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// CHECK: debug v => _1;
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// CHECK: debug y => _4;
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// CHECK: _3 = &raw mut (_1.0: i32);
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// CHECK: (*_3) = const 5_i32;
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// CHECK: _5 = copy (_1.0: i32);
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// CHECK: _4 = Eq(move _5, const 5_i32);
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let mut v = (1,);
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unsafe {
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*&raw mut v.0 = 5;
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}
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let y = { v.0 } == 5;
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}
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fn main() {
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foo();
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bar();
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}
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