Merge commit '11a0cceab966e5ff1058ddbcab5977e8a1d6d290' into subtree-update_cg_gcc_2023-10-09

compiler/rustc_codegen_gcc/src/declare.rs

@@ -1,4 +1,6 @@
 use gccjit::{Function, FunctionType, GlobalKind, LValue, RValue, Type};
+#[cfg(feature="master")]
+use gccjit::{FnAttribute, ToRValue};
 use rustc_codegen_ssa::traits::BaseTypeMethods;
 use rustc_middle::ty::Ty;
 use rustc_span::Symbol;
@@ -114,6 +116,44 @@ fn declare_raw_fn<'gcc>(cx: &CodegenCx<'gcc, '_>, name: &str, _callconv: () /*ll
                 .collect();
             let func = cx.context.new_function(None, cx.linkage.get(), return_type, &params, mangle_name(name), variadic);
             cx.functions.borrow_mut().insert(name.to_string(), func);
+
+            #[cfg(feature="master")]
+            if name == "rust_eh_personality" {
+                // NOTE: GCC will sometimes change the personality function set on a function from
+                // rust_eh_personality to __gcc_personality_v0 as an optimization.
+                // As such, we need to create a weak alias from __gcc_personality_v0 to
+                // rust_eh_personality in order to avoid a linker error.
+                // This needs to be weak in order to still allow using the standard
+                // __gcc_personality_v0 when the linking to it.
+                // Since aliases don't work (maybe because of a bug in LTO partitioning?), we
+                // create a wrapper function that calls rust_eh_personality.
+
+                let params: Vec<_> = param_types.into_iter().enumerate()
+                    .map(|(index, param)| cx.context.new_parameter(None, *param, &format!("param{}", index))) // TODO(antoyo): set name.
+                    .collect();
+                let gcc_func = cx.context.new_function(None, FunctionType::Exported, return_type, &params, "__gcc_personality_v0", variadic);
+
+                // We need a normal extern function for the crates that access rust_eh_personality
+                // without defining it, otherwise we'll get a compiler error.
+                //
+                // For the crate defining it, that needs to be a weak alias instead.
+                gcc_func.add_attribute(FnAttribute::Weak);
+
+                let block = gcc_func.new_block("start");
+                let mut args = vec![];
+                for param in &params {
+                    args.push(param.to_rvalue());
+                }
+                let call = cx.context.new_call(None, func, &args);
+                if return_type == cx.type_void() {
+                    block.add_eval(None, call);
+                    block.end_with_void_return(None);
+                }
+                else {
+                    block.end_with_return(None, call);
+                }
+            }
+
             func
         };