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Save 2 pointers in TerminatorKind (96 → 80 bytes) #126784

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Jun 24, 2024
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Save 2 pointers in TerminatorKind (96 → 80 bytes) #126784

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4 changes: 2 additions & 2 deletions compiler/rustc_middle/src/mir/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1817,11 +1817,11 @@ mod size_asserts {
use super::*;
use rustc_data_structures::static_assert_size;
// tidy-alphabetical-start
static_assert_size!(BasicBlockData<'_>, 144);
static_assert_size!(BasicBlockData<'_>, 128);
static_assert_size!(LocalDecl<'_>, 40);
static_assert_size!(SourceScopeData<'_>, 64);
static_assert_size!(Statement<'_>, 32);
static_assert_size!(Terminator<'_>, 112);
static_assert_size!(Terminator<'_>, 96);
static_assert_size!(VarDebugInfo<'_>, 88);
// tidy-alphabetical-end
}
8 changes: 4 additions & 4 deletions compiler/rustc_middle/src/mir/syntax.rs
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Expand Up @@ -730,7 +730,7 @@ pub enum TerminatorKind<'tcx> {
/// reused across function calls without duplicating the contents.
/// The span for each arg is also included
/// (e.g. `a` and `b` in `x.foo(a, b)`).
args: Vec<Spanned<Operand<'tcx>>>,
args: Box<[Spanned<Operand<'tcx>>]>,
/// Where the returned value will be written
destination: Place<'tcx>,
/// Where to go after this call returns. If none, the call necessarily diverges.
Expand Down Expand Up @@ -837,7 +837,7 @@ pub enum TerminatorKind<'tcx> {
template: &'tcx [InlineAsmTemplatePiece],

/// The operands for the inline assembly, as `Operand`s or `Place`s.
operands: Vec<InlineAsmOperand<'tcx>>,
operands: Box<[InlineAsmOperand<'tcx>]>,

/// Miscellaneous options for the inline assembly.
options: InlineAsmOptions,
Expand All @@ -849,7 +849,7 @@ pub enum TerminatorKind<'tcx> {
/// Valid targets for the inline assembly.
/// The first element is the fallthrough destination, unless
/// InlineAsmOptions::NORETURN is set.
targets: Vec<BasicBlock>,
targets: Box<[BasicBlock]>,

/// Action to be taken if the inline assembly unwinds. This is present
/// if and only if InlineAsmOptions::MAY_UNWIND is set.
Expand Down Expand Up @@ -1561,6 +1561,6 @@ mod size_asserts {
static_assert_size!(PlaceElem<'_>, 24);
static_assert_size!(Rvalue<'_>, 40);
static_assert_size!(StatementKind<'_>, 16);
static_assert_size!(TerminatorKind<'_>, 96);
static_assert_size!(TerminatorKind<'_>, 80);
// tidy-alphabetical-end
}
2 changes: 1 addition & 1 deletion compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
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Expand Up @@ -170,7 +170,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
.map(|arg|
Ok(Spanned { node: self.parse_operand(*arg)?, span: self.thir.exprs[*arg].span } )
)
.collect::<PResult<Vec<_>>>()?;
.collect::<PResult<Box<[_]>>>()?;
Ok(TerminatorKind::Call {
func: fun,
args,
Expand Down
5 changes: 3 additions & 2 deletions compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
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Expand Up @@ -152,10 +152,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
source_info,
TerminatorKind::Call {
func: exchange_malloc,
args: vec![
args: [
Spanned { node: Operand::Move(size), span: DUMMY_SP },
Spanned { node: Operand::Move(align), span: DUMMY_SP },
],
]
.into(),
destination: storage,
target: Some(success),
unwind: UnwindAction::Continue,
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_mir_build/src/build/expr/into.rs
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Expand Up @@ -238,7 +238,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
ExprKind::Call { ty: _, fun, ref args, from_hir_call, fn_span } => {
let fun = unpack!(block = this.as_local_operand(block, fun));
let args: Vec<_> = args
let args: Box<[_]> = args
.into_iter()
.copied()
.map(|arg| Spanned {
Expand Down Expand Up @@ -485,7 +485,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
operands,
options,
line_spans,
targets,
targets: targets.into_boxed_slice(),
unwind: if options.contains(InlineAsmOptions::MAY_UNWIND) {
UnwindAction::Continue
} else {
Expand Down
7 changes: 4 additions & 3 deletions compiler/rustc_mir_build/src/build/matches/test.rs
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Expand Up @@ -324,7 +324,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
user_ty: None,
const_: method,
})),
args: vec![Spanned { node: Operand::Move(ref_src), span }],
args: [Spanned { node: Operand::Move(ref_src), span }].into(),
destination: temp,
target: Some(target_block),
unwind: UnwindAction::Continue,
Expand Down Expand Up @@ -486,10 +486,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {

const_: method,
})),
args: vec![
args: [
Spanned { node: Operand::Copy(val), span: DUMMY_SP },
Spanned { node: expect, span: DUMMY_SP },
],
]
.into(),
destination: eq_result,
target: Some(eq_block),
unwind: UnwindAction::Continue,
Expand Down
6 changes: 2 additions & 4 deletions compiler/rustc_mir_dataflow/src/elaborate_drops.rs
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Expand Up @@ -650,10 +650,8 @@ where
[ty.into()],
self.source_info.span,
),
args: vec![Spanned {
node: Operand::Move(Place::from(ref_place)),
span: DUMMY_SP,
}],
args: [Spanned { node: Operand::Move(Place::from(ref_place)), span: DUMMY_SP }]
.into(),
destination: unit_temp,
target: Some(succ),
unwind: unwind.into_action(),
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_mir_dataflow/src/framework/tests.rs
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Expand Up @@ -34,7 +34,7 @@ fn mock_body<'tcx>() -> mir::Body<'tcx> {
2,
mir::TerminatorKind::Call {
func: mir::Operand::Copy(dummy_place.clone()),
args: vec![],
args: [].into(),
destination: dummy_place.clone(),
target: Some(mir::START_BLOCK),
unwind: mir::UnwindAction::Continue,
Expand All @@ -48,7 +48,7 @@ fn mock_body<'tcx>() -> mir::Body<'tcx> {
4,
mir::TerminatorKind::Call {
func: mir::Operand::Copy(dummy_place.clone()),
args: vec![],
args: [].into(),
destination: dummy_place.clone(),
target: Some(mir::START_BLOCK),
unwind: mir::UnwindAction::Continue,
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_mir_transform/src/coroutine.rs
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Expand Up @@ -677,8 +677,8 @@ fn transform_async_context<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {

fn eliminate_get_context_call<'tcx>(bb_data: &mut BasicBlockData<'tcx>) -> Local {
let terminator = bb_data.terminator.take().unwrap();
if let TerminatorKind::Call { mut args, destination, target, .. } = terminator.kind {
let arg = args.pop().unwrap();
if let TerminatorKind::Call { args, destination, target, .. } = terminator.kind {
let [arg] = *Box::try_from(args).unwrap();
let local = arg.node.place().unwrap().local;

let arg = Rvalue::Use(arg.node);
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_mir_transform/src/coverage/tests.rs
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Expand Up @@ -134,7 +134,7 @@ impl<'tcx> MockBlocks<'tcx> {
some_from_block,
TerminatorKind::Call {
func: Operand::Copy(self.dummy_place.clone()),
args: vec![],
args: [].into(),
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Box<[T]> implements Default, might be easier to use that

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or Box::new([]) and let CoerceUnsized do the work

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If you don't mind, I'd like to just leave it .into() because that's what I'm using elsewhere in the places where it's not empty.

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Well I'd rather you just use Box::new([x, y, z]) everywhere -- I think trailing .into() is just ugly to read and not as analogous to vec![x, y, z] 😆

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I liked it when it was

                        args: [
                            Spanned { node: Operand::Move(size), span: DUMMY_SP },
                            Spanned { node: Operand::Move(size), span: DUMMY_SP },
                            Spanned { node: Operand::Move(align), span: DUMMY_SP },
                            Spanned { node: Operand::Move(align), span: DUMMY_SP },
                        ].into(),

But of course rustfmt won't let us have nice things.

I'm inclined to leave it the one that doesn't say "vec" nor "box" and works with both, but I can change them all to Box::new if you feel strongly 🙃

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Also note that this particular code is just building fake MIR for unit tests, so it's relatively unimportant.

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Well this is one of many examples -- I wasn't going to leave a comment on all of them, so the fact it's building fake MIR or processing real MIR isn't really relevant

destination: self.dummy_place.clone(),
target: Some(TEMP_BLOCK),
unwind: UnwindAction::Continue,
Expand Down
13 changes: 7 additions & 6 deletions compiler/rustc_mir_transform/src/inline.rs
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Expand Up @@ -624,8 +624,7 @@ impl<'tcx> Inliner<'tcx> {
};

// Copy the arguments if needed.
let args: Vec<_> =
self.make_call_args(args, &callsite, caller_body, &callee_body, return_block);
let args = self.make_call_args(args, &callsite, caller_body, &callee_body, return_block);

let mut integrator = Integrator {
args: &args,
Expand Down Expand Up @@ -736,12 +735,12 @@ impl<'tcx> Inliner<'tcx> {

fn make_call_args(
&self,
args: Vec<Spanned<Operand<'tcx>>>,
args: Box<[Spanned<Operand<'tcx>>]>,
callsite: &CallSite<'tcx>,
caller_body: &mut Body<'tcx>,
callee_body: &Body<'tcx>,
return_block: Option<BasicBlock>,
) -> Vec<Local> {
) -> Box<[Local]> {
let tcx = self.tcx;

// There is a bit of a mismatch between the *caller* of a closure and the *callee*.
Expand All @@ -768,7 +767,8 @@ impl<'tcx> Inliner<'tcx> {
//
// and the vector is `[closure_ref, tmp0, tmp1, tmp2]`.
if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() {
let mut args = args.into_iter();
// FIXME(edition_2024): switch back to a normal method call.
let mut args = <_>::into_iter(args);
let self_ = self.create_temp_if_necessary(
args.next().unwrap().node,
callsite,
Expand Down Expand Up @@ -802,7 +802,8 @@ impl<'tcx> Inliner<'tcx> {

closure_ref_arg.chain(tuple_tmp_args).collect()
} else {
args.into_iter()
// FIXME(edition_2024): switch back to a normal method call.
<_>::into_iter(args)
.map(|a| self.create_temp_if_necessary(a.node, callsite, caller_body, return_block))
.collect()
}
Expand Down
4 changes: 3 additions & 1 deletion compiler/rustc_mir_transform/src/instsimplify.rs
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@@ -1,6 +1,7 @@
//! Performs various peephole optimizations.

use crate::simplify::simplify_duplicate_switch_targets;
use crate::take_array;
use rustc_ast::attr;
use rustc_middle::bug;
use rustc_middle::mir::*;
Expand Down Expand Up @@ -285,7 +286,8 @@ impl<'tcx> InstSimplifyContext<'tcx, '_> {
return;
}

let Some(arg_place) = args.pop().unwrap().node.place() else { return };
let Ok([arg]) = take_array(args) else { return };
let Some(arg_place) = arg.node.place() else { return };

statements.push(Statement {
source_info: terminator.source_info,
Expand Down
10 changes: 8 additions & 2 deletions compiler/rustc_mir_transform/src/lib.rs
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Expand Up @@ -160,8 +160,9 @@ fn remap_mir_for_const_eval_select<'tcx>(
} if let ty::FnDef(def_id, _) = *const_.ty().kind()
&& tcx.is_intrinsic(def_id, sym::const_eval_select) =>
{
let [tupled_args, called_in_const, called_at_rt]: [_; 3] =
std::mem::take(args).try_into().unwrap();
let Ok([tupled_args, called_in_const, called_at_rt]) = take_array(args) else {
unreachable!()
};
let ty = tupled_args.node.ty(&body.local_decls, tcx);
let fields = ty.tuple_fields();
let num_args = fields.len();
Expand Down Expand Up @@ -211,6 +212,11 @@ fn remap_mir_for_const_eval_select<'tcx>(
body
}

fn take_array<T, const N: usize>(b: &mut Box<[T]>) -> Result<[T; N], Box<[T]>> {
let b: Box<[T; N]> = std::mem::take(b).try_into()?;
Ok(*b)
}

fn is_mir_available(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
tcx.mir_keys(()).contains(&def_id)
}
Expand Down
61 changes: 23 additions & 38 deletions compiler/rustc_mir_transform/src/lower_intrinsics.rs
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@@ -1,5 +1,6 @@
//! Lowers intrinsic calls

use crate::take_array;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{bug, span_bug};
Expand Down Expand Up @@ -50,42 +51,34 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
sym::copy_nonoverlapping => {
let target = target.unwrap();
let mut args = args.drain(..);
let Ok([src, dst, count]) = take_array(args) else {
bug!("Wrong arguments for copy_non_overlapping intrinsic");
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Intrinsic(Box::new(
NonDivergingIntrinsic::CopyNonOverlapping(
rustc_middle::mir::CopyNonOverlapping {
src: args.next().unwrap().node,
dst: args.next().unwrap().node,
count: args.next().unwrap().node,
src: src.node,
dst: dst.node,
count: count.node,
},
),
)),
});
assert_eq!(
args.next(),
None,
"Extra argument for copy_non_overlapping intrinsic"
);
drop(args);
terminator.kind = TerminatorKind::Goto { target };
}
sym::assume => {
let target = target.unwrap();
let mut args = args.drain(..);
let Ok([arg]) = take_array(args) else {
bug!("Wrong arguments for assume intrinsic");
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Intrinsic(Box::new(
NonDivergingIntrinsic::Assume(args.next().unwrap().node),
NonDivergingIntrinsic::Assume(arg.node),
)),
});
assert_eq!(
args.next(),
None,
"Extra argument for copy_non_overlapping intrinsic"
);
drop(args);
terminator.kind = TerminatorKind::Goto { target };
}
sym::wrapping_add
Expand All @@ -100,13 +93,9 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
| sym::unchecked_shl
| sym::unchecked_shr => {
let target = target.unwrap();
let lhs;
let rhs;
{
let mut args = args.drain(..);
lhs = args.next().unwrap();
rhs = args.next().unwrap();
}
let Ok([lhs, rhs]) = take_array(args) else {
bug!("Wrong arguments for {} intrinsic", intrinsic.name);
};
let bin_op = match intrinsic.name {
sym::wrapping_add => BinOp::Add,
sym::wrapping_sub => BinOp::Sub,
Expand All @@ -132,13 +121,9 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
sym::add_with_overflow | sym::sub_with_overflow | sym::mul_with_overflow => {
if let Some(target) = *target {
let lhs;
let rhs;
{
let mut args = args.drain(..);
lhs = args.next().unwrap();
rhs = args.next().unwrap();
}
let Ok([lhs, rhs]) = take_array(args) else {
bug!("Wrong arguments for {} intrinsic", intrinsic.name);
};
let bin_op = match intrinsic.name {
sym::add_with_overflow => BinOp::AddWithOverflow,
sym::sub_with_overflow => BinOp::SubWithOverflow,
Expand Down Expand Up @@ -174,7 +159,7 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
}
sym::read_via_copy => {
let [arg] = args.as_slice() else {
let Ok([arg]) = take_array(args) else {
span_bug!(terminator.source_info.span, "Wrong number of arguments");
};
let derefed_place = if let Some(place) = arg.node.place()
Expand Down Expand Up @@ -207,7 +192,7 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
sym::write_via_move => {
let target = target.unwrap();
let Ok([ptr, val]) = <[_; 2]>::try_from(std::mem::take(args)) else {
let Ok([ptr, val]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for write_via_move intrinsic",
Expand Down Expand Up @@ -247,7 +232,7 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
sym::offset => {
let target = target.unwrap();
let Ok([ptr, delta]) = <[_; 2]>::try_from(std::mem::take(args)) else {
let Ok([ptr, delta]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for offset intrinsic",
Expand All @@ -264,7 +249,7 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
sym::transmute | sym::transmute_unchecked => {
let dst_ty = destination.ty(local_decls, tcx).ty;
let Ok([arg]) = <[_; 1]>::try_from(std::mem::take(args)) else {
let Ok([arg]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for transmute intrinsic",
Expand All @@ -289,7 +274,7 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
}
}
sym::aggregate_raw_ptr => {
let Ok([data, meta]) = <[_; 2]>::try_from(std::mem::take(args)) else {
let Ok([data, meta]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for aggregate_raw_ptr intrinsic",
Expand Down Expand Up @@ -317,7 +302,7 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
terminator.kind = TerminatorKind::Goto { target };
}
sym::ptr_metadata => {
let Ok([ptr]) = <[_; 1]>::try_from(std::mem::take(args)) else {
let Ok([ptr]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for ptr_metadata intrinsic",
Expand Down
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