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-rw-r--r--src/doc/rustc-dev-guide/src/thir.md163
1 files changed, 106 insertions, 57 deletions
diff --git a/src/doc/rustc-dev-guide/src/thir.md b/src/doc/rustc-dev-guide/src/thir.md
index 4f8e6512c..2a811be3d 100644
--- a/src/doc/rustc-dev-guide/src/thir.md
+++ b/src/doc/rustc-dev-guide/src/thir.md
@@ -4,7 +4,7 @@
The THIR ("Typed High-Level Intermediate Representation"), previously called HAIR for
"High-Level Abstract IR", is another IR used by rustc that is generated after
-[type checking]. It is (as of <!-- date: 2022-04 --> April 2022) only used for
+[type checking]. It is (as of <!-- date-check --> April 2022) only used for
[MIR construction] and [exhaustiveness checking]. There is also
[an experimental unsafety checker][thir-unsafeck] that operates on the THIR as a replacement for
the current MIR unsafety checker, and can be used instead of the MIR unsafety checker by passing
@@ -47,9 +47,19 @@ which is useful to keep peak memory in check. Having a THIR representation of
all bodies of a crate in memory at the same time would be very heavy.
You can get a debug representation of the THIR by passing the `-Zunpretty=thir-tree` flag
-to `rustc`. Here is how a function with just the statement `let x = 1 + 2;` gets represented in
-THIR:
+to `rustc`.
+
+To demonstrate, let's use the following example:
+
```rust
+fn main() {
+ let x = 1 + 2;
+}
+```
+
+Here is how that gets represented in THIR (as of <!-- date-check --> Aug 2022):
+
+```rust,no_run
Thir {
// no match arms
arms: [],
@@ -57,57 +67,73 @@ Thir {
// expression 0, a literal with a value of 1
Expr {
ty: i32,
- temp_lifetime: Some(Node(6)),
+ temp_lifetime: Some(
+ Node(1),
+ ),
span: oneplustwo.rs:2:13: 2:14 (#0),
kind: Literal {
- literal: Const {
- ty: i32,
- val: Value(Scalar(0x00000001)),
+ lit: Spanned {
+ node: Int(
+ 1,
+ Unsuffixed,
+ ),
+ span: oneplustwo.rs:2:13: 2:14 (#0),
},
- user_ty: None,
- const_id: None,
+ neg: false,
},
},
// expression 1, scope surronding literal 1
Expr {
ty: i32,
- temp_lifetime: Some(Node(6)),
+ temp_lifetime: Some(
+ Node(1),
+ ),
span: oneplustwo.rs:2:13: 2:14 (#0),
kind: Scope {
- region_scope: Node(1),
- lint_level: Explicit(HirId {
- owner: DefId(0:3 ~ oneplustwo[6ccc]::main),
- local_id: 1,
- }),
// reference to expression 0 above
+ region_scope: Node(3),
+ lint_level: Explicit(
+ HirId {
+ owner: DefId(0:3 ~ oneplustwo[6932]::main),
+ local_id: 3,
+ },
+ ),
value: e0,
},
},
// expression 2, literal 2
Expr {
ty: i32,
- temp_lifetime: Some(Node(6)),
+ temp_lifetime: Some(
+ Node(1),
+ ),
span: oneplustwo.rs:2:17: 2:18 (#0),
kind: Literal {
- literal: Const {
- ty: i32,
- val: Value(Scalar(0x00000002)),
+ lit: Spanned {
+ node: Int(
+ 2,
+ Unsuffixed,
+ ),
+ span: oneplustwo.rs:2:17: 2:18 (#0),
},
- user_ty: None,
- const_id: None,
+ neg: false,
},
},
// expression 3, scope surrounding literal 2
Expr {
ty: i32,
- temp_lifetime: Some(Node(6)),
+ temp_lifetime: Some(
+ Node(1),
+ ),
span: oneplustwo.rs:2:17: 2:18 (#0),
kind: Scope {
- region_scope: Node(2),
- lint_level: Explicit(HirId {
- owner: DefId(0:3 ~ oneplustwo[6ccc]::main),
- local_id: 2,
- }),
+ region_scope: Node(4),
+ lint_level: Explicit(
+ HirId {
+ owner: DefId(0:3 ~ oneplustwo[6932]::main),
+ local_id: 4,
+ },
+ ),
// reference to expression 2 above
value: e2,
},
@@ -115,7 +141,9 @@ Thir {
// expression 4, represents 1 + 2
Expr {
ty: i32,
- temp_lifetime: Some(Node(6)),
+ temp_lifetime: Some(
+ Node(1),
+ ),
span: oneplustwo.rs:2:13: 2:18 (#0),
kind: Binary {
op: Add,
@@ -127,30 +155,38 @@ Thir {
// expression 5, scope surronding expression 4
Expr {
ty: i32,
- temp_lifetime: Some(Node(6)),
+ temp_lifetime: Some(
+ Node(1),
+ ),
span: oneplustwo.rs:2:13: 2:18 (#0),
kind: Scope {
- region_scope: Node(3),
- lint_level: Explicit(HirId {
- owner: DefId(0:3 ~ oneplustwo[6ccc]::main),
- local_id: 3,
- }),
+ region_scope: Node(5),
+ lint_level: Explicit(
+ HirId {
+ owner: DefId(0:3 ~ oneplustwo[6932]::main),
+ local_id: 5,
+ },
+ ),
value: e4,
},
},
// expression 6, block around statement
Expr {
ty: (),
- temp_lifetime: Some(Node(8)),
+ temp_lifetime: Some(
+ Node(9),
+ ),
span: oneplustwo.rs:1:11: 3:2 (#0),
kind: Block {
body: Block {
targeted_by_break: false,
- region_scope: Node(7),
+ region_scope: Node(8),
opt_destruction_scope: None,
span: oneplustwo.rs:1:11: 3:2 (#0),
// reference to statement 0 below
- stmts: [ s0 ],
+ stmts: [
+ s0,
+ ],
expr: None,
safety_mode: Safe,
},
@@ -160,25 +196,29 @@ Thir {
Expr {
ty: (),
temp_lifetime: Some(
- Node(8),
+ Node(9),
),
span: oneplustwo.rs:1:11: 3:2 (#0),
kind: Scope {
- region_scope: Node(8),
- lint_level: Explicit(HirId {
- owner: DefId(0:3 ~ oneplustwo[6ccc]::main),
- local_id: 8,
- }),
+ region_scope: Node(9),
+ lint_level: Explicit(
+ HirId {
+ owner: DefId(0:3 ~ oneplustwo[6932]::main),
+ local_id: 9,
+ },
+ ),
value: e6,
},
},
// destruction scope around expression 7
Expr {
ty: (),
- temp_lifetime: Some(Node(8)),
+ temp_lifetime: Some(
+ Node(9),
+ ),
span: oneplustwo.rs:1:11: 3:2 (#0),
kind: Scope {
- region_scope: Destruction(8),
+ region_scope: Destruction(9),
lint_level: Inherited,
value: e7,
},
@@ -188,8 +228,8 @@ Thir {
// let statement
Stmt {
kind: Let {
- remainder_scope: Remainder { block: 7, first_statement_index: 0},
- init_scope: Node(6),
+ remainder_scope: Remainder { block: 8, first_statement_index: 0},
+ init_scope: Node(1),
pattern: Pat {
ty: i32,
span: oneplustwo.rs:2:9: 2:10 (#0),
@@ -197,22 +237,31 @@ Thir {
mutability: Not,
name: "x",
mode: ByValue,
- var: HirId {
- owner: DefId(0:3 ~ oneplustwo[6ccc]::main),
- local_id: 5,
- },
+ var: LocalVarId(
+ HirId {
+ owner: DefId(0:3 ~ oneplustwo[6932]::main),
+ local_id: 7,
+ },
+ ),
ty: i32,
subpattern: None,
is_primary: true,
},
},
- initializer: Some(e5),
- lint_level: Explicit(HirId {
- owner: DefId(0:3 ~ oneplustwo[6ccc]::main),
- local_id: 4,
- }),
+ initializer: Some(
+ e5,
+ ),
+ else_block: None,
+ lint_level: Explicit(
+ HirId {
+ owner: DefId(0:3 ~ oneplustwo[6932]::main),
+ local_id: 6,
+ },
+ ),
},
- opt_destruction_scope: Some(Destruction(6)),
+ opt_destruction_scope: Some(
+ Destruction(1),
+ ),
},
],
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-10 09:29:47 +0000