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dpaoliellodpaoliello
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Change __rust_no_alloc_shim_is_unstable to be a function
1 parent e5a2a6a commit e3597ca

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16 files changed

+143
-112
lines changed

16 files changed

+143
-112
lines changed

‎compiler/rustc_ast/src/expand/allocator.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,7 +22,7 @@ pub fn alloc_error_handler_name(alloc_error_handler_kind: AllocatorKind) -> &'st
2222
}
2323
}
2424

25-
pub const NO_ALLOC_SHIM_IS_UNSTABLE: &str = "__rust_no_alloc_shim_is_unstable";
25+
pub const NO_ALLOC_SHIM_IS_UNSTABLE: &str = "__rust_no_alloc_shim_is_unstable_v2";
2626

2727
pub enum AllocatorTy {
2828
Layout,

‎compiler/rustc_codegen_cranelift/src/allocator.rs

Lines changed: 28 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
11
//! Allocator shim
22
// Adapted from rustc
33

4+
use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
45
use rustc_ast::expand::allocator::{
56
ALLOCATOR_METHODS, AllocatorKind, AllocatorTy, NO_ALLOC_SHIM_IS_UNSTABLE,
67
alloc_error_handler_name, default_fn_name, global_fn_name,
@@ -97,16 +98,31 @@ fn codegen_inner(
9798
data.define(Box::new([val]));
9899
module.define_data(data_id, &data).unwrap();
99100

100-
let data_id = module
101-
.declare_data(
102-
&mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
103-
Linkage::Export,
104-
false,
105-
false,
106-
)
107-
.unwrap();
108-
let mut data = DataDescription::new();
109-
data.set_align(1);
110-
data.define(Box::new([0]));
111-
module.define_data(data_id, &data).unwrap();
101+
{
102+
let sig = Signature {
103+
call_conv: module.target_config().default_call_conv,
104+
params: vec![],
105+
returns: vec![],
106+
};
107+
let func_id = module
108+
.declare_function(
109+
&mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
110+
Linkage::Export,
111+
&sig,
112+
)
113+
.unwrap();
114+
115+
let mut ctx = Context::new();
116+
ctx.func.signature = sig;
117+
let mut func_ctx = FunctionBuilderContext::new();
118+
let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
119+
120+
let block = bcx.create_block();
121+
bcx.switch_to_block(block);
122+
bcx.ins().return_(&[]);
123+
bcx.seal_all_blocks();
124+
bcx.finalize();
125+
126+
module.define_function(func_id, &mut ctx).unwrap();
127+
}
112128
}

‎compiler/rustc_codegen_gcc/src/allocator.rs

Lines changed: 42 additions & 36 deletions
Original file line numberDiff line numberDiff line change
@@ -57,7 +57,7 @@ pub(crate) unsafe fn codegen(
5757
let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
5858
let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
5959

60-
create_wrapper_function(tcx, context, &from_name, &to_name, &types, output);
60+
create_wrapper_function(tcx, context, &from_name, Some(&to_name), &types, output);
6161
}
6262
}
6363

@@ -66,7 +66,7 @@ pub(crate) unsafe fn codegen(
6666
tcx,
6767
context,
6868
&mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
69-
&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind)),
69+
Some(&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind))),
7070
&[usize, usize],
7171
None,
7272
);
@@ -81,21 +81,21 @@ pub(crate) unsafe fn codegen(
8181
let value = context.new_rvalue_from_int(i8, value as i32);
8282
global.global_set_initializer_rvalue(value);
8383

84-
let name = mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE);
85-
let global = context.new_global(None, GlobalKind::Exported, i8, name);
86-
#[cfg(feature = "master")]
87-
global.add_attribute(VarAttribute::Visibility(symbol_visibility_to_gcc(
88-
tcx.sess.default_visibility(),
89-
)));
90-
let value = context.new_rvalue_from_int(i8, 0);
91-
global.global_set_initializer_rvalue(value);
84+
create_wrapper_function(
85+
tcx,
86+
context,
87+
&mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
88+
None,
89+
&[],
90+
None,
91+
);
9292
}
9393

9494
fn create_wrapper_function(
9595
tcx: TyCtxt<'_>,
9696
context: &Context<'_>,
9797
from_name: &str,
98-
to_name: &str,
98+
to_name: Option<&str>,
9999
types: &[Type<'_>],
100100
output: Option<Type<'_>>,
101101
) {
@@ -124,34 +124,40 @@ fn create_wrapper_function(
124124
// TODO(antoyo): emit unwind tables.
125125
}
126126

127-
let args: Vec<_> = types
128-
.iter()
129-
.enumerate()
130-
.map(|(index, typ)| context.new_parameter(None, *typ, format!("param{}", index)))
131-
.collect();
132-
let callee = context.new_function(
133-
None,
134-
FunctionType::Extern,
135-
output.unwrap_or(void),
136-
&args,
137-
to_name,
138-
false,
139-
);
140-
#[cfg(feature = "master")]
141-
callee.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
142-
143127
let block = func.new_block("entry");
144128

145-
let args = args
146-
.iter()
147-
.enumerate()
148-
.map(|(i, _)| func.get_param(i as i32).to_rvalue())
149-
.collect::<Vec<_>>();
150-
let ret = context.new_call(None, callee, &args);
151-
//llvm::LLVMSetTailCall(ret, True);
152-
if output.is_some() {
153-
block.end_with_return(None, ret);
129+
if let Some(to_name) = to_name {
130+
let args: Vec<_> = types
131+
.iter()
132+
.enumerate()
133+
.map(|(index, typ)| context.new_parameter(None, *typ, format!("param{}", index)))
134+
.collect();
135+
let callee = context.new_function(
136+
None,
137+
FunctionType::Extern,
138+
output.unwrap_or(void),
139+
&args,
140+
to_name,
141+
false,
142+
);
143+
#[cfg(feature = "master")]
144+
callee.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
145+
146+
let args = args
147+
.iter()
148+
.enumerate()
149+
.map(|(i, _)| func.get_param(i as i32).to_rvalue())
150+
.collect::<Vec<_>>();
151+
let ret = context.new_call(None, callee, &args);
152+
//llvm::LLVMSetTailCall(ret, True);
153+
if output.is_some() {
154+
block.end_with_return(None, ret);
155+
} else {
156+
block.add_eval(None, ret);
157+
block.end_with_void_return(None);
158+
}
154159
} else {
160+
assert!(output.is_none());
155161
block.end_with_void_return(None);
156162
}
157163

‎compiler/rustc_codegen_llvm/src/allocator.rs

Lines changed: 42 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -57,7 +57,7 @@ pub(crate) unsafe fn codegen(
5757
let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
5858
let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
5959

60-
create_wrapper_function(tcx, &cx, &from_name, &to_name, &args, output, false);
60+
create_wrapper_function(tcx, &cx, &from_name, Some(&to_name), &args, output, false);
6161
}
6262
}
6363

@@ -66,7 +66,7 @@ pub(crate) unsafe fn codegen(
6666
tcx,
6767
&cx,
6868
&mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
69-
&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind)),
69+
Some(&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind))),
7070
&[usize, usize], // size, align
7171
None,
7272
true,
@@ -81,11 +81,16 @@ pub(crate) unsafe fn codegen(
8181
let llval = llvm::LLVMConstInt(i8, val as u64, False);
8282
llvm::set_initializer(ll_g, llval);
8383

84-
let name = mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE);
85-
let ll_g = cx.declare_global(&name, i8);
86-
llvm::set_visibility(ll_g, llvm::Visibility::from_generic(tcx.sess.default_visibility()));
87-
let llval = llvm::LLVMConstInt(i8, 0, False);
88-
llvm::set_initializer(ll_g, llval);
84+
// __rust_no_alloc_shim_is_unstable_v2
85+
create_wrapper_function(
86+
tcx,
87+
&cx,
88+
&mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
89+
None,
90+
&[],
91+
None,
92+
false,
93+
);
8994
}
9095

9196
if tcx.sess.opts.debuginfo != DebugInfo::None {
@@ -99,7 +104,7 @@ fn create_wrapper_function(
99104
tcx: TyCtxt<'_>,
100105
cx: &SimpleCx<'_>,
101106
from_name: &str,
102-
to_name: &str,
107+
to_name: Option<&str>,
103108
args: &[&Type],
104109
output: Option<&Type>,
105110
no_return: bool,
@@ -128,33 +133,38 @@ fn create_wrapper_function(
128133
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
129134
}
130135

131-
let callee = declare_simple_fn(
132-
&cx,
133-
to_name,
134-
llvm::CallConv::CCallConv,
135-
llvm::UnnamedAddr::Global,
136-
llvm::Visibility::Hidden,
137-
ty,
138-
);
139-
if let Some(no_return) = no_return {
140-
// -> ! DIFlagNoReturn
141-
attributes::apply_to_llfn(callee, llvm::AttributePlace::Function, &[no_return]);
142-
}
143-
llvm::set_visibility(callee, llvm::Visibility::Hidden);
144-
145136
let llbb = unsafe { llvm::LLVMAppendBasicBlockInContext(cx.llcx, llfn, c"entry".as_ptr()) };
146-
147137
let mut bx = SBuilder::build(&cx, llbb);
148-
let args = args
149-
.iter()
150-
.enumerate()
151-
.map(|(i, _)| llvm::get_param(llfn, i as c_uint))
152-
.collect::<Vec<_>>();
153-
let ret = bx.call(ty, callee, &args, None);
154-
llvm::LLVMSetTailCall(ret, True);
155-
if output.is_some() {
156-
bx.ret(ret);
138+
139+
if let Some(to_name) = to_name {
140+
let callee = declare_simple_fn(
141+
&cx,
142+
to_name,
143+
llvm::CallConv::CCallConv,
144+
llvm::UnnamedAddr::Global,
145+
llvm::Visibility::Hidden,
146+
ty,
147+
);
148+
if let Some(no_return) = no_return {
149+
// -> ! DIFlagNoReturn
150+
attributes::apply_to_llfn(callee, llvm::AttributePlace::Function, &[no_return]);
151+
}
152+
llvm::set_visibility(callee, llvm::Visibility::Hidden);
153+
154+
let args = args
155+
.iter()
156+
.enumerate()
157+
.map(|(i, _)| llvm::get_param(llfn, i as c_uint))
158+
.collect::<Vec<_>>();
159+
let ret = bx.call(ty, callee, &args, None);
160+
llvm::LLVMSetTailCall(ret, True);
161+
if output.is_some() {
162+
bx.ret(ret);
163+
} else {
164+
bx.ret_void()
165+
}
157166
} else {
167+
assert!(output.is_none());
158168
bx.ret_void()
159169
}
160170
}

‎compiler/rustc_codegen_ssa/src/back/symbol_export.rs

Lines changed: 1 addition & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -219,6 +219,7 @@ fn exported_symbols_provider_local<'tcx>(
219219
.chain([
220220
mangle_internal_symbol(tcx, "__rust_alloc_error_handler"),
221221
mangle_internal_symbol(tcx, OomStrategy::SYMBOL),
222+
mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
222223
])
223224
{
224225
let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, &symbol_name));
@@ -232,19 +233,6 @@ fn exported_symbols_provider_local<'tcx>(
232233
},
233234
));
234235
}
235-
236-
let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(
237-
tcx,
238-
&mangle_internal_symbol(tcx, NO_ALLOC_SHIM_IS_UNSTABLE),
239-
));
240-
symbols.push((
241-
exported_symbol,
242-
SymbolExportInfo {
243-
level: SymbolExportLevel::Rust,
244-
kind: SymbolExportKind::Data,
245-
used: false,
246-
},
247-
))
248236
}
249237

250238
if tcx.sess.instrument_coverage() || tcx.sess.opts.cg.profile_generate.enabled() {

‎compiler/rustc_symbol_mangling/src/v0.rs

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -85,10 +85,10 @@ pub fn mangle_internal_symbol<'tcx>(tcx: TyCtxt<'tcx>, item_name: &str) -> Strin
8585
if item_name == "rust_eh_personality" {
8686
// rust_eh_personality must not be renamed as LLVM hard-codes the name
8787
return "rust_eh_personality".to_owned();
88-
} else if item_name == "__rust_no_alloc_shim_is_unstable" {
88+
} else if item_name == "__rust_no_alloc_shim_is_unstable_v2" {
8989
// Temporary back compat hack to give people the chance to migrate to
9090
// include #[rustc_std_internal_symbol].
91-
return "__rust_no_alloc_shim_is_unstable".to_owned();
91+
return "__rust_no_alloc_shim_is_unstable_v2".to_owned();
9292
}
9393

9494
let prefix = "_R";

‎library/alloc/src/alloc.rs

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -31,8 +31,14 @@ unsafe extern "Rust" {
3131
#[rustc_std_internal_symbol]
3232
fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8;
3333

34+
#[rustc_nounwind]
35+
#[rustc_std_internal_symbol]
36+
#[cfg(not(bootstrap))]
37+
fn __rust_no_alloc_shim_is_unstable_v2();
3438
#[rustc_std_internal_symbol]
39+
#[cfg(bootstrap)]
3540
static __rust_no_alloc_shim_is_unstable: u8;
41+
3642
}
3743

3844
/// The global memory allocator.
@@ -88,7 +94,10 @@ pub unsafe fn alloc(layout: Layout) -> *mut u8 {
8894
unsafe {
8995
// Make sure we don't accidentally allow omitting the allocator shim in
9096
// stable code until it is actually stabilized.
97+
#[cfg(bootstrap)]
9198
core::ptr::read_volatile(&__rust_no_alloc_shim_is_unstable);
99+
#[cfg(not(bootstrap))]
100+
__rust_no_alloc_shim_is_unstable_v2();
92101

93102
__rust_alloc(layout.size(), layout.align())
94103
}
@@ -171,7 +180,10 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
171180
unsafe {
172181
// Make sure we don't accidentally allow omitting the allocator shim in
173182
// stable code until it is actually stabilized.
183+
#[cfg(bootstrap)]
174184
core::ptr::read_volatile(&__rust_no_alloc_shim_is_unstable);
185+
#[cfg(not(bootstrap))]
186+
__rust_no_alloc_shim_is_unstable_v2();
175187

176188
__rust_alloc_zeroed(layout.size(), layout.align())
177189
}

‎src/tools/miri/src/shims/extern_static.rs

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -45,10 +45,6 @@ impl<'tcx> MiriMachine<'tcx> {
4545

4646
/// Sets up the "extern statics" for this machine.
4747
pub fn init_extern_statics(ecx: &mut MiriInterpCx<'tcx>) -> InterpResult<'tcx> {
48-
// "__rust_no_alloc_shim_is_unstable"
49-
let val = ImmTy::from_int(0, ecx.machine.layouts.u8); // always 0, value does not matter
50-
Self::alloc_extern_static(ecx, "__rust_no_alloc_shim_is_unstable", val)?;
51-
5248
// "__rust_alloc_error_handler_should_panic"
5349
let val = ecx.tcx.sess.opts.unstable_opts.oom.should_panic();
5450
let val = ImmTy::from_int(val, ecx.machine.layouts.u8);

‎src/tools/miri/src/shims/foreign_items.rs

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -731,6 +731,10 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
731731
this.mem_copy(ptr_src, ptr_dest, Size::from_bytes(n), true)?;
732732
this.write_pointer(ptr_dest, dest)?;
733733
}
734+
"__rust_no_alloc_shim_is_unstable_v2" => {
735+
// This is a no-op shim that only exists to prevent making the allocator shims instantly stable.
736+
this.check_shim(abi, Conv::Rust, link_name, args)?;
737+
}
734738

735739
// math functions (note that there are also intrinsics for some other functions)
736740
#[rustfmt::skip]

‎tests/codegen/alloc-optimisation.rs

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -5,8 +5,7 @@
55
pub fn alloc_test(data: u32) {
66
// CHECK-LABEL: @alloc_test
77
// CHECK-NEXT: start:
8-
// CHECK-NEXT: {{.*}} load volatile i8, ptr @{{.*}}__rust_no_alloc_shim_is_unstable, align 1
9-
// CHECK-NEXT: ret void
8+
// CHECK-NEXT: tail call void @__rust_no_alloc_shim_is_unstable_v2()
109
let x = Box::new(data);
1110
drop(x);
1211
}

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