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Don't use an allocator shim for #[global_allocator]

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This makes it possible to use liballoc/libstd in combination with
`--emit obj` if you use `#[global_allocator]`. Making it work for the
default libstd allocator would require weak functions, which are not
well supported on all systems.
This commit is contained in:
bjorn3 2021-07-03 16:46:41 +02:00 committed by bjorn3
parent db3faa78d0
commit 002aa8ed90
1 changed files with 38 additions and 35 deletions
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73
src/allocator.rs
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@ -3,10 +3,11 @@
use crate::prelude::*; use crate::prelude::*;
use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS}; use rustc_ast::expand::allocator::{
alloc_error_handler_name, AllocatorKind, AllocatorTy, ALLOCATOR_METHODS,
};
use rustc_codegen_ssa::base::allocator_kind_for_codegen; use rustc_codegen_ssa::base::allocator_kind_for_codegen;
use rustc_session::config::OomStrategy; use rustc_session::config::OomStrategy;
use rustc_span::symbol::sym;
/// Returns whether an allocator shim was created /// Returns whether an allocator shim was created
pub(crate) fn codegen( pub(crate) fn codegen(
@ -34,41 +35,43 @@ fn codegen_inner(
) { ) {
let usize_ty = module.target_config().pointer_type(); let usize_ty = module.target_config().pointer_type();
for method in ALLOCATOR_METHODS { if kind == AllocatorKind::Default {
let mut arg_tys = Vec::with_capacity(method.inputs.len()); for method in ALLOCATOR_METHODS {
for ty in method.inputs.iter() { let mut arg_tys = Vec::with_capacity(method.inputs.len());
match *ty { for ty in method.inputs.iter() {
AllocatorTy::Layout => { match *ty {
arg_tys.push(usize_ty); // size AllocatorTy::Layout => {
arg_tys.push(usize_ty); // align arg_tys.push(usize_ty); // size
arg_tys.push(usize_ty); // align
}
AllocatorTy::Ptr => arg_tys.push(usize_ty),
AllocatorTy::Usize => arg_tys.push(usize_ty),
AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
} }
AllocatorTy::Ptr => arg_tys.push(usize_ty),
AllocatorTy::Usize => arg_tys.push(usize_ty),
AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
} }
let output = match method.output {
AllocatorTy::ResultPtr => Some(usize_ty),
AllocatorTy::Unit => None,
AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
panic!("invalid allocator output")
}
};
let sig = Signature {
call_conv: module.target_config().default_call_conv,
params: arg_tys.iter().cloned().map(AbiParam::new).collect(),
returns: output.into_iter().map(AbiParam::new).collect(),
};
crate::common::create_wrapper_function(
module,
unwind_context,
sig,
&format!("__rust_{}", method.name),
&AllocatorKind::Default.fn_name(method.name),
);
} }
let output = match method.output {
AllocatorTy::ResultPtr => Some(usize_ty),
AllocatorTy::Unit => None,
AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
panic!("invalid allocator output")
}
};
let sig = Signature {
call_conv: module.target_config().default_call_conv,
params: arg_tys.iter().cloned().map(AbiParam::new).collect(),
returns: output.into_iter().map(AbiParam::new).collect(),
};
crate::common::create_wrapper_function(
module,
unwind_context,
sig,
&format!("__rust_{}", method.name),
&kind.fn_name(method.name),
);
} }
let sig = Signature { let sig = Signature {
@ -81,7 +84,7 @@ fn codegen_inner(
unwind_context, unwind_context,
sig, sig,
"__rust_alloc_error_handler", "__rust_alloc_error_handler",
&alloc_error_handler_kind.fn_name(sym::oom), &alloc_error_handler_name(alloc_error_handler_kind),
); );
let data_id = module.declare_data(OomStrategy::SYMBOL, Linkage::Export, false, false).unwrap(); let data_id = module.declare_data(OomStrategy::SYMBOL, Linkage::Export, false, false).unwrap();