bjoernager/rust
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Added llvm lifetime annotations to function call argument temporaries.

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The goal of this change is to ensure that llvm will do stack slot
optimization on these temporaries. This ensures that in code like:
```rust
const A: [u8; 1024] = [0; 1024];

fn copy_const() {
    f(A);
    f(A);
}
```
we only use 1024 bytes of stack space, instead of 2048 bytes.
This commit is contained in:
David Venhoek 2022-06-22 11:24:34 +02:00
parent 3d829a0922
commit a174d65709
1 changed files with 16 additions and 2 deletions
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18
compiler/rustc_codegen_ssa/src/mir/block.rs
View file

@ -132,6 +132,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
llargs: &[Bx::Value],
destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
cleanup: Option<mir::BasicBlock>,
argument_tmps: &[PlaceRef<'tcx, <Bx as BackendTypes>::Value>],
) {
// If there is a cleanup block and the function we're calling can unwind, then
// do an invoke, otherwise do a call.
@ -172,6 +173,9 @@ 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 argument_tmps {
bx.lifetime_end(tmp.llval, tmp.layout.size);
}
fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
}
} else {
@ -186,6 +190,9 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
}
if let Some((ret_dest, target)) = destination {
for tmp in argument_tmps {
bx.lifetime_end(tmp.llval, tmp.layout.size);
}
fx.store_return(bx, ret_dest, &fn_abi.ret, llret);
self.funclet_br(fx, bx, target);
} else {
@ -415,6 +422,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
args,
Some((ReturnDest::Nothing, target)),
unwind,
&[],
);
}
@ -492,7 +500,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let (fn_abi, llfn) = common::build_langcall(&bx, Some(span), lang_item);
// Codegen the actual panic invoke/call.
helper.do_call(self, &mut bx, fn_abi, llfn, &args, None, cleanup);
helper.do_call(self, &mut bx, fn_abi, llfn, &args, None, cleanup, &[]);
}
fn codegen_abort_terminator(
@ -508,7 +516,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let (fn_abi, llfn) = common::build_langcall(&bx, Some(span), LangItem::PanicNoUnwind);
// Codegen the actual panic invoke/call.
helper.do_call(self, &mut bx, fn_abi, llfn, &[], None, None);
helper.do_call(self, &mut bx, fn_abi, llfn, &[], None, None, &[]);
}
/// Returns `true` if this is indeed a panic intrinsic and codegen is done.
@ -579,6 +587,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&[msg.0, msg.1, location],
target.as_ref().map(|bb| (ReturnDest::Nothing, *bb)),
cleanup,
&[],
);
} else {
// a NOP
@ -786,6 +795,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
(args, None)
};
let mut argument_tmps = vec![];
'make_args: for (i, arg) in first_args.iter().enumerate() {
let mut op = self.codegen_operand(&mut bx, arg);
@ -851,8 +861,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
(&mir::Operand::Copy(_), Ref(_, None, _))
| (&mir::Operand::Constant(_), Ref(_, None, _)) => {
let tmp = PlaceRef::alloca(&mut bx, op.layout);
bx.lifetime_start(tmp.llval, tmp.layout.size);
op.val.store(&mut bx, tmp);
op.val = Ref(tmp.llval, None, tmp.align);
argument_tmps.push(tmp);
}
_ => {}
}
@ -925,6 +937,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&llargs,
target.as_ref().map(|&target| (ret_dest, target)),
cleanup,
&argument_tmps,
);
bx.switch_to_block(bb_fail);
@ -942,6 +955,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&llargs,
target.as_ref().map(|&target| (ret_dest, target)),
cleanup,
&argument_tmps,
);
}