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Refactor variadics #638

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Refactor variadics #638

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3866a89
Refactor `is_va_decl` to use `.map()` and `.unwrap_or_default()`.
kkysen Aug 23, 2022
593da11
Refactored `match_vacopy` with `?`.
kkysen Aug 23, 2022
67deb33
Replaced an `as &str` with a `.as_str()`.
kkysen Aug 23, 2022
0560612
Refactored `if ... { return None; }`s in `match` arms into `match` `i…
kkysen Aug 23, 2022
c2e1136
Replaced `args.len() == n` and then `args[0]`, etc. with `match`ing o…
kkysen Aug 23, 2022
f9eec5f
Reformatted the `match_vapart` `match` after refactoring it.
kkysen Aug 23, 2022
51b3d91
Refactored out repeated `match`ing on `__builtin_va_*` into a `.strip…
kkysen Aug 23, 2022
15575c3
Improved doc comments on inner variadic matching functions.
kkysen Aug 23, 2022
35701ce
Made the variadic-matching inner functions closures instead so we don…
kkysen Aug 23, 2022
578dc62
Renamed the local `ast_context` to `ast` for brevity since it's used …
kkysen Aug 23, 2022
66cebb5
Removed non-local control flow (`return None`) and variable declarati…
kkysen Aug 23, 2022
8fae26f
Fixed confusing "`*` pointer" language in docs, which could be a `**`…
kkysen Aug 24, 2022
eaccb5c
Favor `.unwrap_or(false)` over `.unwrap_or_default()` as it's less cl…
kkysen Aug 24, 2022
b4428a3
Revert "Refactored out repeated `match`ing on `__builtin_va_*` into a…
kkysen Aug 24, 2022
0e48fdb
Refactored out `let ast = &self.ast_context` for brevity in `fn match…
kkysen Aug 24, 2022
8ac1538
Re-formatted `match_or!`s onto 1 line each. 2 lines with an indented…
kkysen Aug 24, 2022
2439ed4
Revert "Refactor `is_va_decl` to use `.map()` and `.unwrap_or_default…
kkysen Aug 25, 2022
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149 changes: 59 additions & 90 deletions c2rust-transpile/src/translator/variadic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,21 +9,21 @@ pub enum VaPart {

macro_rules! match_or {
([$e:expr] $p:pat => $r:tt) => {
let $r = match $e {
$p => $r,
_ => return None,
};
match $e {
$p => Some($r),
_ => None,
}
};
([$e:expr] $p:pat if $g:expr => $r:tt) => {
let $r = match $e {
$p if $g => $r,
_ => return None,
};
match $e {
$p if $g => Some($r),
_ => None,
}
};
}

impl<'c> Translation<'c> {
/// Returns true iff `va_start`, `va_end`, or `va_copy` may be called on `decl_id`.
/// Returns `true` iff `va_start`, `va_end`, or `va_copy` may be called on `decl_id`.
pub fn is_va_decl(&self, decl_id: CDeclId) -> bool {
let fn_ctx = self.function_context.borrow();
if let Some(ref decls) = fn_ctx.va_list_decl_ids {
Expand All @@ -34,105 +34,74 @@ impl<'c> Translation<'c> {
}

pub fn match_vastart(&self, expr: CExprId) -> Option<CDeclId> {
// struct-based va_list (e.g. x86_64)
fn match_vastart_struct(ast_context: &TypedAstContext, expr: CExprId) -> Option<CDeclId> {
match_or! { [ast_context[expr].kind]
CExprKind::ImplicitCast(_, e, _, _, _) => e }
match_or! { [ast_context[e].kind]
CExprKind::DeclRef(_, va_id, _) => va_id }
let ast = &self.ast_context;

// `struct`-based `va_list` (e.g. x86_64).
let match_vastart_struct = || {
let e = match_or! { [ast[expr].kind] CExprKind::ImplicitCast(_, e, _, _, _) => e }?;
let va_id = match_or! { [ast[e].kind] CExprKind::DeclRef(_, va_id, _) => va_id }?;
Some(va_id)
}
};

// struct-based va_list (e.g. x86_64) where va_list is accessed as a struct member
// supporting this pattern is necessary to transpile apache httpd
fn match_vastart_struct_member(
ast_context: &TypedAstContext,
expr: CExprId,
) -> Option<CDeclId> {
match_or! { [ast_context[expr].kind]
CExprKind::ImplicitCast(_, me, _, _, _) => me }
match_or! { [ast_context[me].kind]
CExprKind::Member(_, e, _, _, _) => e }
match_or! { [ast_context[e].kind]
CExprKind::DeclRef(_, va_id, _) => va_id }
// `struct`-based `va_list` (e.g. x86_64) where `va_list` is accessed as a `struct` member.
//
// Supporting this pattern is necessary to transpile apache httpd.
let match_vastart_struct_member = || {
let me = match_or! { [ast[expr].kind] CExprKind::ImplicitCast(_, me, _, _, _) => me }?;
let e = match_or! { [ast[me].kind] CExprKind::Member(_, e, _, _, _) => e }?;
let va_id = match_or! { [ast[e].kind] CExprKind::DeclRef(_, va_id, _) => va_id }?;
Some(va_id)
}
};

// struct-based va_list (e.g. x86_64) where va_list is accessed as a member of a struct pointer
// supporting this pattern is necessary to transpile [graphviz](https://gitlab.com/graphviz/graphviz/-/blob/5.0.0/lib/sfio/sftable.c#L321)
fn match_vastart_struct_pointer_member(
ast_context: &TypedAstContext,
expr: CExprId,
) -> Option<CDeclId> {
match_or! { [ast_context[expr].kind]
CExprKind::ImplicitCast(_, me, _, _, _) => me }
match_or! { [ast_context[me].kind]
CExprKind::Member(_, ie, _, _, _) => ie }
match_or! { [ast_context[ie].kind]
CExprKind::ImplicitCast(_, e, _, _, _) => e }
match_or! { [ast_context[e].kind]
CExprKind::DeclRef(_, va_id, _) => va_id }
// `struct`-based `va_list` (e.g. x86_64) where `va_list` is accessed as a member of a `struct *`.
//
// Supporting this pattern is necessary to transpile
// [graphviz](https://gitlab.com/graphviz/graphviz/-/blob/5.0.0/lib/sfio/sftable.c#L321).
let match_vastart_struct_pointer_member = || {
let me = match_or! { [ast[expr].kind] CExprKind::ImplicitCast(_, me, _, _, _) => me }?;
let ie = match_or! { [ast[me].kind] CExprKind::Member(_, ie, _, _, _) => ie }?;
let e = match_or! { [ast[ie].kind] CExprKind::ImplicitCast(_, e, _, _, _) => e }?;
let va_id = match_or! { [ast[e].kind] CExprKind::DeclRef(_, va_id, _) => va_id }?;
Some(va_id)
}
};

// char pointer-based va_list (e.g. x86)
fn match_vastart_pointer(ast_context: &TypedAstContext, expr: CExprId) -> Option<CDeclId> {
match_or! { [ast_context[expr].kind]
CExprKind::DeclRef(_, va_id, _) => va_id }
// `char *`-based `va_list` (e.g. x86).
let match_vastart_pointer = || {
let va_id = match_or! { [ast[expr].kind] CExprKind::DeclRef(_, va_id, _) => va_id }?;
Some(va_id)
}
};

match_vastart_struct(&self.ast_context, expr)
.or_else(|| match_vastart_pointer(&self.ast_context, expr))
.or_else(|| match_vastart_struct_member(&self.ast_context, expr))
.or_else(|| match_vastart_struct_pointer_member(&self.ast_context, expr))
match_vastart_struct()
.or_else(match_vastart_pointer)
.or_else(match_vastart_struct_member)
.or_else(match_vastart_struct_pointer_member)
}

pub fn match_vaend(&self, expr: CExprId) -> Option<CDeclId> {
self.match_vastart(expr)
}

pub fn match_vacopy(&self, dst_expr: CExprId, src_expr: CExprId) -> Option<(CDeclId, CDeclId)> {
let dst_id = self.match_vastart(dst_expr);
let src_id = self.match_vastart(src_expr);
if let (Some(did), Some(sid)) = (dst_id, src_id) {
return Some((did, sid));
}
None
let dst_id = self.match_vastart(dst_expr)?;
let src_id = self.match_vastart(src_expr)?;
Some((dst_id, src_id))
}

pub fn match_vapart(&self, expr: CExprId) -> Option<VaPart> {
match_or! { [self.ast_context[expr].kind]
CExprKind::Call(_, func, ref args) => (func, args) }
match_or! { [self.ast_context[func].kind]
CExprKind::ImplicitCast(_, fexp, CastKind::BuiltinFnToFnPtr, _, _) => fexp }
match_or! { [self.ast_context[fexp].kind]
CExprKind::DeclRef(_, decl_id, _) => decl_id }
match_or! { [self.ast_context[decl_id].kind]
CDeclKind::Function { ref name, .. } => name }
match name as &str {
"__builtin_va_start" => {
if args.len() != 2 {
return None;
}
self.match_vastart(args[0]).map(VaPart::Start)
}

"__builtin_va_copy" => {
if args.len() != 2 {
return None;
}
self.match_vacopy(args[0], args[1])
.map(|(did, sid)| VaPart::Copy(did, sid))
}

"__builtin_va_end" => {
if args.len() != 1 {
return None;
}
self.match_vaend(args[0]).map(VaPart::End)
}

let ast = &self.ast_context;

let (func, args) =
match_or! { [ast[expr].kind] CExprKind::Call(_, func, ref args) => (func, args) }?;
let fexp = match_or! { [ast[func].kind] CExprKind::ImplicitCast(_, fexp, CastKind::BuiltinFnToFnPtr, _, _) => fexp }?;
let decl_id = match_or! { [ast[fexp].kind] CExprKind::DeclRef(_, decl_id, _) => decl_id }?;
let name = match_or! { [ast[decl_id].kind] CDeclKind::Function { ref name, .. } => name }?;

match (name.as_str(), args.as_slice()) {
("__builtin_va_start", &[expr, _]) => self.match_vastart(expr).map(VaPart::Start),
("__builtin_va_copy", &[dst_expr, src_expr]) => self
.match_vacopy(dst_expr, src_expr)
.map(|(did, sid)| VaPart::Copy(did, sid)),
("__builtin_va_end", &[expr]) => self.match_vaend(expr).map(VaPart::End),
_ => None,
}
}
Expand Down