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44 changes: 23 additions & 21 deletions src/asm.md
Original file line number Diff line number Diff line change
Expand Up @@ -10,12 +10,13 @@ through all of the compiler layers down to LLVM codegen. Throughout the various

- The template string, which is stored as an array of `InlineAsmTemplatePiece`. Each piece
represents either a literal or a placeholder for an operand (just like format strings).
```rust
pub enum InlineAsmTemplatePiece {
String(String),
Placeholder { operand_idx: usize, modifier: Option<char>, span: Span },
}
```

```rust
pub enum InlineAsmTemplatePiece {
String(String),
Placeholder { operand_idx: usize, modifier: Option<char>, span: Span },
}
```

- The list of operands to the `asm!` (`in`, `[late]out`, `in[late]out`, `sym`, `const`). These are
represented differently at each stage of lowering, but follow a common pattern:
Expand All @@ -34,21 +35,22 @@ or a `fn`.
- The options set at the end of the `asm!` macro. The only ones that are of particular interest to
rustc are `NORETURN` which makes `asm!` return `!` instead of `()`, and `RAW` which disables format
string parsing. The remaining options are mostly passed through to LLVM with little processing.
```rust
bitflags::bitflags! {
pub struct InlineAsmOptions: u16 {
const PURE = 1 << 0;
const NOMEM = 1 << 1;
const READONLY = 1 << 2;
const PRESERVES_FLAGS = 1 << 3;
const NORETURN = 1 << 4;
const NOSTACK = 1 << 5;
const ATT_SYNTAX = 1 << 6;
const RAW = 1 << 7;
const MAY_UNWIND = 1 << 8;
}
}
```

```rust
bitflags::bitflags! {
pub struct InlineAsmOptions: u16 {
const PURE = 1 << 0;
const NOMEM = 1 << 1;
const READONLY = 1 << 2;
const PRESERVES_FLAGS = 1 << 3;
const NORETURN = 1 << 4;
const NOSTACK = 1 << 5;
const ATT_SYNTAX = 1 << 6;
const RAW = 1 << 7;
const MAY_UNWIND = 1 << 8;
}
}
```

## AST

Expand Down