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Move computation of allocator shim contents to cg_ssa

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In the future this should make it easier to use weak symbols for the
allocator shim on platforms that properly support weak symbols. And it
would allow reusing the allocator shim code for handling default
implementations of the upcoming externally implementable items feature
on platforms that don't properly support weak symbols.
This commit is contained in:
bjorn3 2025-10-09 14:08:55 +00:00
parent 67b7b7f66b
commit b453c19e91
1 changed files with 29 additions and 50 deletions
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79
src/allocator.rs
View file

@ -3,10 +3,9 @@
use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
use rustc_ast::expand::allocator::{
ALLOC_ERROR_HANDLER, ALLOCATOR_METHODS, AllocatorKind, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE,
default_fn_name, global_fn_name,
AllocatorMethod, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE, default_fn_name, global_fn_name,
};
use rustc_codegen_ssa::base::allocator_kind_for_codegen;
use rustc_codegen_ssa::base::{allocator_kind_for_codegen, allocator_shim_contents};
use rustc_session::config::OomStrategy;
use rustc_symbol_mangling::mangle_internal_symbol;
@ -15,74 +14,54 @@ use crate::prelude::*;
/// Returns whether an allocator shim was created
pub(crate) fn codegen(tcx: TyCtxt<'_>, module: &mut dyn Module) -> bool {
let Some(kind) = allocator_kind_for_codegen(tcx) else { return false };
codegen_inner(
tcx,
module,
kind,
tcx.alloc_error_handler_kind(()).unwrap(),
tcx.sess.opts.unstable_opts.oom,
);
let methods = allocator_shim_contents(tcx, kind);
codegen_inner(tcx, module, &methods, tcx.sess.opts.unstable_opts.oom);
true
}
fn codegen_inner(
tcx: TyCtxt<'_>,
module: &mut dyn Module,
kind: AllocatorKind,
alloc_error_handler_kind: AllocatorKind,
methods: &[AllocatorMethod],
oom_strategy: OomStrategy,
) {
let usize_ty = module.target_config().pointer_type();
if kind == AllocatorKind::Default {
for method in ALLOCATOR_METHODS {
let mut arg_tys = Vec::with_capacity(method.inputs.len());
for input in method.inputs.iter() {
match input.ty {
AllocatorTy::Layout => {
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),
for method in methods {
let mut arg_tys = Vec::with_capacity(method.inputs.len());
for input in method.inputs.iter() {
match input.ty {
AllocatorTy::Layout => {
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::Never | 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,
sig,
&mangle_internal_symbol(tcx, &global_fn_name(method.name)),
&mangle_internal_symbol(tcx, &default_fn_name(method.name)),
);
}
}
let output = match method.output {
AllocatorTy::ResultPtr => Some(usize_ty),
AllocatorTy::Never | AllocatorTy::Unit => None,
AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
panic!("invalid allocator output")
}
};
if alloc_error_handler_kind == AllocatorKind::Default {
let sig = Signature {
call_conv: module.target_config().default_call_conv,
params: vec![AbiParam::new(usize_ty), AbiParam::new(usize_ty)],
returns: vec![],
params: arg_tys.iter().cloned().map(AbiParam::new).collect(),
returns: output.into_iter().map(AbiParam::new).collect(),
};
crate::common::create_wrapper_function(
module,
sig,
&mangle_internal_symbol(tcx, &global_fn_name(ALLOC_ERROR_HANDLER)),
&mangle_internal_symbol(tcx, &default_fn_name(ALLOC_ERROR_HANDLER)),
&mangle_internal_symbol(tcx, &global_fn_name(method.name)),
&mangle_internal_symbol(tcx, &default_fn_name(method.name)),
);
}