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Extract a create_wrapper_function for use in allocator shim writing #306

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merged 1 commit into from
Jul 17, 2023
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Extract a create_wrapper_function for use in allocator shim writing #306

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109 changes: 50 additions & 59 deletions src/allocator.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
#[cfg(feature="master")]
use gccjit::FnAttribute;
use gccjit::{FunctionType, GlobalKind, ToRValue};
use gccjit::{Context, FunctionType, GlobalKind, ToRValue, Type};
use rustc_ast::expand::allocator::{
alloc_error_handler_name, default_fn_name, global_fn_name, AllocatorKind, AllocatorTy,
ALLOCATOR_METHODS, NO_ALLOC_SHIM_IS_UNSTABLE,
Expand All @@ -22,7 +22,6 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
};
let i8 = context.new_type::<i8>();
let i8p = i8.make_pointer();
let void = context.new_type::<()>();

if kind == AllocatorKind::Default {
for method in ALLOCATOR_METHODS {
Expand All @@ -47,67 +46,62 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
panic!("invalid allocator output")
}
};
let name = global_fn_name(method.name);
let from_name = global_fn_name(method.name);
let to_name = default_fn_name(method.name);

let args: Vec<_> = types.iter().enumerate()
.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
.collect();
let func = context.new_function(None, FunctionType::Exported, output.unwrap_or(void), &args, name, false);
create_wrapper_function(tcx, context, &from_name, &to_name, &types, output);
}
}

if tcx.sess.target.options.default_hidden_visibility {
#[cfg(feature="master")]
func.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
}
if tcx.sess.must_emit_unwind_tables() {
// TODO(antoyo): emit unwind tables.
}
// FIXME(bjorn3): Add noreturn attribute
create_wrapper_function(
tcx,
context,
"__rust_alloc_error_handler",
&alloc_error_handler_name(alloc_error_handler_kind),
&[usize, usize],
None,
);

let callee = default_fn_name(method.name);
let args: Vec<_> = types.iter().enumerate()
.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
.collect();
let callee = context.new_function(None, FunctionType::Extern, output.unwrap_or(void), &args, callee, false);
#[cfg(feature="master")]
callee.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));

let block = func.new_block("entry");

let args = args
.iter()
.enumerate()
.map(|(i, _)| func.get_param(i as i32).to_rvalue())
.collect::<Vec<_>>();
let ret = context.new_call(None, callee, &args);
//llvm::LLVMSetTailCall(ret, True);
if output.is_some() {
block.end_with_return(None, ret);
}
else {
block.end_with_void_return(None);
}
let name = OomStrategy::SYMBOL.to_string();
let global = context.new_global(None, GlobalKind::Exported, i8, name);
let value = tcx.sess.opts.unstable_opts.oom.should_panic();
let value = context.new_rvalue_from_int(i8, value as i32);
global.global_set_initializer_rvalue(value);

// TODO(@Commeownist): Check if we need to emit some extra debugging info in certain circumstances
// as described in https://github.com/rust-lang/rust/commit/77a96ed5646f7c3ee8897693decc4626fe380643
}
}
let name = NO_ALLOC_SHIM_IS_UNSTABLE.to_string();
let global = context.new_global(None, GlobalKind::Exported, i8, name);
let value = context.new_rvalue_from_int(i8, 0);
global.global_set_initializer_rvalue(value);
}

fn create_wrapper_function(
tcx: TyCtxt<'_>,
context: &Context<'_>,
from_name: &str,
to_name: &str,
types: &[Type<'_>],
output: Option<Type<'_>>,
) {
let void = context.new_type::<()>();

let types = [usize, usize];
let name = "__rust_alloc_error_handler".to_string();
let args: Vec<_> = types.iter().enumerate()
.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
.collect();
let func = context.new_function(None, FunctionType::Exported, void, &args, name, false);
let func = context.new_function(None, FunctionType::Exported, output.unwrap_or(void), &args, from_name, false);

if tcx.sess.target.default_hidden_visibility {
if tcx.sess.target.options.default_hidden_visibility {
#[cfg(feature="master")]
func.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
}
if tcx.sess.must_emit_unwind_tables() {
// TODO(antoyo): emit unwind tables.
}

let callee = alloc_error_handler_name(alloc_error_handler_kind);
let args: Vec<_> = types.iter().enumerate()
.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
.collect();
let callee = context.new_function(None, FunctionType::Extern, void, &args, callee, false);
let callee = context.new_function(None, FunctionType::Extern, output.unwrap_or(void), &args, to_name, false);
#[cfg(feature="master")]
callee.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));

Expand All @@ -118,18 +112,15 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
.enumerate()
.map(|(i, _)| func.get_param(i as i32).to_rvalue())
.collect::<Vec<_>>();
let _ret = context.new_call(None, callee, &args);
let ret = context.new_call(None, callee, &args);
//llvm::LLVMSetTailCall(ret, True);
block.end_with_void_return(None);

let name = OomStrategy::SYMBOL.to_string();
let global = context.new_global(None, GlobalKind::Exported, i8, name);
let value = tcx.sess.opts.unstable_opts.oom.should_panic();
let value = context.new_rvalue_from_int(i8, value as i32);
global.global_set_initializer_rvalue(value);
if output.is_some() {
block.end_with_return(None, ret);
}
else {
block.end_with_void_return(None);
}

let name = NO_ALLOC_SHIM_IS_UNSTABLE.to_string();
let global = context.new_global(None, GlobalKind::Exported, i8, name);
let value = context.new_rvalue_from_int(i8, 0);
global.global_set_initializer_rvalue(value);
// TODO(@Commeownist): Check if we need to emit some extra debugging info in certain circumstances
// as described in https://github.com/rust-lang/rust/commit/77a96ed5646f7c3ee8897693decc4626fe380643
}