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Describe lifetime of call argument temporaries passed indirectly

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This commit is contained in:
Tomasz Miąsko
2025-03-14 10:48:02 +01:00
parent a69bc17fb8
commit 3b7ca287a7
4 changed files with 108 additions and 42 deletions
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48
compiler/rustc_codegen_ssa/src/mir/block.rs
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@@ -1,6 +1,6 @@
use std::cmp;
use rustc_abi::{BackendRepr, ExternAbi, HasDataLayout, Reg, WrappingRange};
use rustc_abi::{BackendRepr, ExternAbi, HasDataLayout, Reg, Size, WrappingRange};
use rustc_ast as ast;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_data_structures::packed::Pu128;
@@ -158,7 +158,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
llargs: &[Bx::Value],
destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
mut unwind: mir::UnwindAction,
copied_constant_arguments: &[PlaceRef<'tcx, <Bx as BackendTypes>::Value>],
lifetime_ends_after_call: &[(Bx::Value, Size)],
instance: Option<Instance<'tcx>>,
mergeable_succ: bool,
) -> MergingSucc {
@@ -245,8 +245,8 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
if let Some((ret_dest, target)) = destination {
bx.switch_to_block(fx.llbb(target));
fx.set_debug_loc(bx, self.terminator.source_info);
for tmp in copied_constant_arguments {
bx.lifetime_end(tmp.val.llval, tmp.layout.size);
for &(tmp, size) in lifetime_ends_after_call {
bx.lifetime_end(tmp, size);
}
fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
}
@@ -259,8 +259,8 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
}
if let Some((ret_dest, target)) = destination {
for tmp in copied_constant_arguments {
bx.lifetime_end(tmp.val.llval, tmp.layout.size);
for &(tmp, size) in lifetime_ends_after_call {
bx.lifetime_end(tmp, size);
}
fx.store_return(bx, ret_dest, &fn_abi.ret, llret);
self.funclet_br(fx, bx, target, mergeable_succ)
@@ -1048,7 +1048,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
(args, None)
};
let mut copied_constant_arguments = vec![];
// When generating arguments we sometimes introduce temporary allocations with lifetime
// that extend for the duration of a call. Keep track of those allocations and their sizes
// to generate `lifetime_end` when the call returns.
let mut lifetime_ends_after_call: Vec<(Bx::Value, Size)> = Vec::new();
'make_args: for (i, arg) in first_args.iter().enumerate() {
let mut op = self.codegen_operand(bx, &arg.node);
@@ -1136,12 +1139,18 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
bx.lifetime_start(tmp.val.llval, tmp.layout.size);
op.val.store(bx, tmp);
op.val = Ref(tmp.val);
copied_constant_arguments.push(tmp);
lifetime_ends_after_call.push((tmp.val.llval, tmp.layout.size));
}
_ => {}
}
self.codegen_argument(bx, op, &mut llargs, &fn_abi.args[i]);
self.codegen_argument(
bx,
op,
&mut llargs,
&fn_abi.args[i],
&mut lifetime_ends_after_call,
);
}
let num_untupled = untuple.map(|tup| {
self.codegen_arguments_untupled(
@@ -1149,6 +1158,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&tup.node,
&mut llargs,
&fn_abi.args[first_args.len()..],
&mut lifetime_ends_after_call,
)
});
@@ -1173,7 +1183,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
);
let last_arg = fn_abi.args.last().unwrap();
self.codegen_argument(bx, location, &mut llargs, last_arg);
self.codegen_argument(
bx,
location,
&mut llargs,
last_arg,
&mut lifetime_ends_after_call,
);
}
let fn_ptr = match (instance, llfn) {
@@ -1189,7 +1205,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&llargs,
destination,
unwind,
&copied_constant_arguments,
&lifetime_ends_after_call,
instance,
mergeable_succ,
)
@@ -1479,6 +1495,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
op: OperandRef<'tcx, Bx::Value>,
llargs: &mut Vec<Bx::Value>,
arg: &ArgAbi<'tcx, Ty<'tcx>>,
lifetime_ends_after_call: &mut Vec<(Bx::Value, Size)>,
) {
match arg.mode {
PassMode::Ignore => return,
@@ -1517,7 +1534,9 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
None => arg.layout.align.abi,
};
let scratch = PlaceValue::alloca(bx, arg.layout.size, required_align);
bx.lifetime_start(scratch.llval, arg.layout.size);
op.val.store(bx, scratch.with_type(arg.layout));
lifetime_ends_after_call.push((scratch.llval, arg.layout.size));
(scratch.llval, scratch.align, true)
}
PassMode::Cast { .. } => {
@@ -1538,7 +1557,9 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// alignment requirements may be higher than the type's alignment, so copy
// to a higher-aligned alloca.
let scratch = PlaceValue::alloca(bx, arg.layout.size, required_align);
bx.lifetime_start(scratch.llval, arg.layout.size);
bx.typed_place_copy(scratch, op_place_val, op.layout);
lifetime_ends_after_call.push((scratch.llval, arg.layout.size));
(scratch.llval, scratch.align, true)
} else {
(op_place_val.llval, op_place_val.align, true)
@@ -1620,6 +1641,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
operand: &mir::Operand<'tcx>,
llargs: &mut Vec<Bx::Value>,
args: &[ArgAbi<'tcx, Ty<'tcx>>],
lifetime_ends_after_call: &mut Vec<(Bx::Value, Size)>,
) -> usize {
let tuple = self.codegen_operand(bx, operand);
@@ -1632,13 +1654,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
for i in 0..tuple.layout.fields.count() {
let field_ptr = tuple_ptr.project_field(bx, i);
let field = bx.load_operand(field_ptr);
self.codegen_argument(bx, field, llargs, &args[i]);
self.codegen_argument(bx, field, llargs, &args[i], lifetime_ends_after_call);
}
} else {
// If the tuple is immediate, the elements are as well.
for i in 0..tuple.layout.fields.count() {
let op = tuple.extract_field(self, bx, i);
self.codegen_argument(bx, op, llargs, &args[i]);
self.codegen_argument(bx, op, llargs, &args[i], lifetime_ends_after_call);
}
}
tuple.layout.fields.count()