Auto merge of #109507 - Amanieu:panic-oom-payload, r=davidtwco

Report allocation errors as panics

OOM is now reported as a panic but with a custom payload type (`AllocErrorPanicPayload`) which holds the layout that was passed to `handle_alloc_error`.

This should be review one commit at a time:
- The first commit adds `AllocErrorPanicPayload` and changes allocation errors to always be reported as panics.
- The second commit removes `#[alloc_error_handler]` and the `alloc_error_hook` API.

ACP: https://github.com/rust-lang/libs-team/issues/192

Closes #51540
Closes #51245

example/alloc_example.rs

@@ -1,4 +1,4 @@
-#![feature(start, core_intrinsics, alloc_error_handler, lang_items)]
+#![feature(start, core_intrinsics, lang_items)]
 #![no_std]
 
 extern crate alloc;
@@ -21,11 +21,6 @@ fn panic_handler(_: &core::panic::PanicInfo) -> ! {
     core::intrinsics::abort();
 }
 
-#[alloc_error_handler]
-fn alloc_error_handler(_: alloc::alloc::Layout) -> ! {
-    core::intrinsics::abort();
-}
-
 #[lang = "eh_personality"]
 fn eh_personality() -> ! {
     loop {}

src/allocator.rs

@@ -5,11 +5,10 @@
 use rustc_middle::bug;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::OomStrategy;
-use rustc_span::symbol::sym;
 
 use crate::GccContext;
 
-pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_name: &str, kind: AllocatorKind, alloc_error_handler_kind: AllocatorKind) {
+pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_name: &str, kind: AllocatorKind) {
     let context = &mods.context;
     let usize =
         match tcx.sess.target.pointer_width {
@@ -87,37 +86,6 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_nam
         // as described in https://github.com/rust-lang/rust/commit/77a96ed5646f7c3ee8897693decc4626fe380643
     }
 
-    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);
-
-    if tcx.sess.target.default_hidden_visibility {
-        #[cfg(feature="master")]
-        func.add_attribute(FnAttribute::Visibility(gccjit::Visibility::Hidden));
-    }
-
-    let callee = alloc_error_handler_kind.fn_name(sym::oom);
-    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);
-    #[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);
-    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();

src/lib.rs

@@ -163,11 +163,11 @@ fn target_features(&self, sess: &Session, allow_unstable: bool) -> Vec<Symbol> {
 }
 
 impl ExtraBackendMethods for GccCodegenBackend {
-    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, module_name: &str, kind: AllocatorKind, alloc_error_handler_kind: AllocatorKind) -> Self::Module {
+    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, module_name: &str, kind: AllocatorKind) -> Self::Module {
         let mut mods = GccContext {
             context: Context::default(),
         };
-        unsafe { allocator::codegen(tcx, &mut mods, module_name, kind, alloc_error_handler_kind); }
+        unsafe { allocator::codegen(tcx, &mut mods, module_name, kind); }
         mods
     }