Auto merge of #86844 - bjorn3:global_alloc_improvements, r=pnkfelix
Support #[global_allocator] without the allocator shim This makes it possible to use liballoc/libstd in combination with `--emit obj` if you use `#[global_allocator]`. This is what rust-for-linux uses right now and systemd may use in the future. Currently they have to depend on the exact implementation of the allocator shim to create one themself as `--emit obj` doesn't create an allocator shim. Note that currently the allocator shim also defines the oom error handler, which is normally required too. Once `#![feature(default_alloc_error_handler)]` becomes the only option, this can be avoided. In addition when using only fallible allocator methods and either `--cfg no_global_oom_handling` for liballoc (like rust-for-linux) or `--gc-sections` no references to the oom error handler will exist. To avoid this feature being insta-stable, you will have to define `__rust_no_alloc_shim_is_unstable` to avoid linker errors. (Labeling this with both T-compiler and T-lang as it originally involved both an implementation detail and had an insta-stable user facing change. As noted above, the `__rust_no_alloc_shim_is_unstable` symbol requirement should prevent unintended dependence on this unstable feature.)
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commit
a3c1f42c18
121
src/allocator.rs
121
src/allocator.rs
@ -1,11 +1,13 @@
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#[cfg(feature="master")]
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use gccjit::FnAttribute;
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use gccjit::{FunctionType, GlobalKind, ToRValue};
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use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
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use rustc_ast::expand::allocator::{
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alloc_error_handler_name, default_fn_name, global_fn_name, AllocatorKind, AllocatorTy,
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ALLOCATOR_METHODS, NO_ALLOC_SHIM_IS_UNSTABLE,
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};
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use rustc_middle::bug;
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use rustc_middle::ty::TyCtxt;
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use rustc_session::config::OomStrategy;
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use rustc_span::symbol::sym;
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use crate::GccContext;
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@ -22,69 +24,71 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
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let i8p = i8.make_pointer();
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let void = context.new_type::<()>();
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for method in ALLOCATOR_METHODS {
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let mut types = Vec::with_capacity(method.inputs.len());
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for ty in method.inputs.iter() {
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match *ty {
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AllocatorTy::Layout => {
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types.push(usize);
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types.push(usize);
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if kind == AllocatorKind::Default {
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for method in ALLOCATOR_METHODS {
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let mut types = Vec::with_capacity(method.inputs.len());
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for ty in method.inputs.iter() {
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match *ty {
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AllocatorTy::Layout => {
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types.push(usize);
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types.push(usize);
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}
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AllocatorTy::Ptr => types.push(i8p),
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AllocatorTy::Usize => types.push(usize),
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AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
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}
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AllocatorTy::Ptr => types.push(i8p),
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AllocatorTy::Usize => types.push(usize),
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AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
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}
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}
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let output = match method.output {
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AllocatorTy::ResultPtr => Some(i8p),
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AllocatorTy::Unit => None,
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let output = match method.output {
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AllocatorTy::ResultPtr => Some(i8p),
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AllocatorTy::Unit => None,
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AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
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panic!("invalid allocator output")
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AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
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panic!("invalid allocator output")
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}
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};
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let name = global_fn_name(method.name);
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let args: Vec<_> = types.iter().enumerate()
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.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
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.collect();
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let func = context.new_function(None, FunctionType::Exported, output.unwrap_or(void), &args, name, false);
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if tcx.sess.target.options.default_hidden_visibility {
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#[cfg(feature="master")]
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func.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
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}
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if tcx.sess.must_emit_unwind_tables() {
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// TODO(antoyo): emit unwind tables.
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}
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};
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let name = format!("__rust_{}", method.name);
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let args: Vec<_> = types.iter().enumerate()
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.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
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.collect();
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let func = context.new_function(None, FunctionType::Exported, output.unwrap_or(void), &args, name, false);
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if tcx.sess.target.options.default_hidden_visibility {
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let callee = default_fn_name(method.name);
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let args: Vec<_> = types.iter().enumerate()
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.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
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.collect();
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let callee = context.new_function(None, FunctionType::Extern, output.unwrap_or(void), &args, callee, false);
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#[cfg(feature="master")]
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func.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
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}
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if tcx.sess.must_emit_unwind_tables() {
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// TODO(antoyo): emit unwind tables.
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}
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callee.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
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let callee = kind.fn_name(method.name);
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let args: Vec<_> = types.iter().enumerate()
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.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
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.collect();
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let callee = context.new_function(None, FunctionType::Extern, output.unwrap_or(void), &args, callee, false);
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#[cfg(feature="master")]
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callee.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
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let block = func.new_block("entry");
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let block = func.new_block("entry");
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let args = args
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.iter()
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.enumerate()
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.map(|(i, _)| func.get_param(i as i32).to_rvalue())
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.collect::<Vec<_>>();
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let ret = context.new_call(None, callee, &args);
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//llvm::LLVMSetTailCall(ret, True);
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if output.is_some() {
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block.end_with_return(None, ret);
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}
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else {
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block.end_with_void_return(None);
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}
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let args = args
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.iter()
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.enumerate()
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.map(|(i, _)| func.get_param(i as i32).to_rvalue())
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.collect::<Vec<_>>();
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let ret = context.new_call(None, callee, &args);
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//llvm::LLVMSetTailCall(ret, True);
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if output.is_some() {
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block.end_with_return(None, ret);
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// TODO(@Commeownist): Check if we need to emit some extra debugging info in certain circumstances
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// as described in https://github.com/rust-lang/rust/commit/77a96ed5646f7c3ee8897693decc4626fe380643
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}
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else {
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block.end_with_void_return(None);
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}
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// TODO(@Commeownist): Check if we need to emit some extra debugging info in certain circumstances
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// as described in https://github.com/rust-lang/rust/commit/77a96ed5646f7c3ee8897693decc4626fe380643
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}
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let types = [usize, usize];
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@ -99,7 +103,7 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
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func.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
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}
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let callee = alloc_error_handler_kind.fn_name(sym::oom);
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let callee = alloc_error_handler_name(alloc_error_handler_kind);
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let args: Vec<_> = types.iter().enumerate()
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.map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
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.collect();
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@ -123,4 +127,9 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
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let value = tcx.sess.opts.unstable_opts.oom.should_panic();
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let value = context.new_rvalue_from_int(i8, value as i32);
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global.global_set_initializer_rvalue(value);
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let name = NO_ALLOC_SHIM_IS_UNSTABLE.to_string();
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let global = context.new_global(None, GlobalKind::Exported, i8, name);
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let value = context.new_rvalue_from_int(i8, 0);
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global.global_set_initializer_rvalue(value);
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}
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