bjoernager/rust
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Implement Make handle_alloc_error default to panic (for no_std + liballoc)

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Related: https://github.com/rust-lang/rust/issues/66741

Guarded with `#![feature(default_alloc_error_handler)]` a default
`alloc_error_handler` is called, if a custom allocator is used and no
other custom `#[alloc_error_handler]` is defined.

The panic message does not contain the size anymore, because it would
pull in the fmt machinery, which would blow up the code size
significantly.
This commit is contained in:
Harald Hoyer 2020-09-07 10:45:20 +02:00
parent f283d3f02c
commit cadd12b5f0
12 changed files with 292 additions and 7 deletions
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45
compiler/rustc_codegen_llvm/src/allocator.rs
View file

@ -3,11 +3,17 @@ use libc::c_uint;
use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
use rustc_middle::bug;
use rustc_middle::ty::TyCtxt;
use rustc_span::symbol::sym;
use crate::llvm::{self, False, True};
use crate::ModuleLlvm;
pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut ModuleLlvm, kind: AllocatorKind) {
pub(crate) unsafe fn codegen(
tcx: TyCtxt<'_>,
mods: &mut ModuleLlvm,
kind: AllocatorKind,
has_alloc_error_handler: bool,
) {
let llcx = &*mods.llcx;
let llmod = mods.llmod();
let usize = match &tcx.sess.target.target.target_pointer_width[..] {
@ -82,4 +88,41 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut ModuleLlvm, kind: Alloc
}
llvm::LLVMDisposeBuilder(llbuilder);
}
// rust alloc error handler
let args = [usize, usize]; // size, align
let ty = llvm::LLVMFunctionType(void, args.as_ptr(), args.len() as c_uint, False);
let name = format!("__rust_alloc_error_handler");
let llfn = llvm::LLVMRustGetOrInsertFunction(llmod, name.as_ptr().cast(), name.len(), ty);
// -> ! DIFlagNoReturn
llvm::Attribute::NoReturn.apply_llfn(llvm::AttributePlace::Function, llfn);
if tcx.sess.target.target.options.default_hidden_visibility {
llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
}
if tcx.sess.must_emit_unwind_tables() {
attributes::emit_uwtable(llfn, true);
}
let kind = if has_alloc_error_handler { AllocatorKind::Global } else { AllocatorKind::Default };
let callee = kind.fn_name(sym::oom);
let callee = llvm::LLVMRustGetOrInsertFunction(llmod, callee.as_ptr().cast(), callee.len(), ty);
// -> ! DIFlagNoReturn
llvm::Attribute::NoReturn.apply_llfn(llvm::AttributePlace::Function, callee);
llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);
let llbb = llvm::LLVMAppendBasicBlockInContext(llcx, llfn, "entry\0".as_ptr().cast());
let llbuilder = llvm::LLVMCreateBuilderInContext(llcx);
llvm::LLVMPositionBuilderAtEnd(llbuilder, llbb);
let args = args
.iter()
.enumerate()
.map(|(i, _)| llvm::LLVMGetParam(llfn, i as c_uint))
.collect::<Vec<_>>();
let ret = llvm::LLVMRustBuildCall(llbuilder, callee, args.as_ptr(), args.len() as c_uint, None);
llvm::LLVMSetTailCall(ret, True);
llvm::LLVMBuildRetVoid(llbuilder);
llvm::LLVMDisposeBuilder(llbuilder);
}