Emit unwind info for main and alloc shim

Fixes rust-lang#988

Author: bjorn3

src/allocator.rs

@@ -13,22 +13,30 @@ use crate::prelude::*;
 use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
 
 /// Returns whether an allocator shim was created
-pub(crate) fn codegen(tcx: TyCtxt<'_>, module: &mut Module<impl Backend + 'static>) -> bool {
+pub(crate) fn codegen(
+    tcx: TyCtxt<'_>,
+    module: &mut Module<impl Backend + 'static>,
+    unwind_context: &mut UnwindContext<'_>,
+) -> bool {
     let any_dynamic_crate = tcx.dependency_formats(LOCAL_CRATE).iter().any(|(_, list)| {
         use rustc_middle::middle::dependency_format::Linkage;
         list.iter().any(|&linkage| linkage == Linkage::Dynamic)
     });
     if any_dynamic_crate {
         false
     } else if let Some(kind) = tcx.allocator_kind() {
-        codegen_inner(module, kind);
+        codegen_inner(module, unwind_context, kind);
         true
     } else {
         false
     }
 }
 
-fn codegen_inner(module: &mut Module<impl Backend + 'static>, kind: AllocatorKind) {
+fn codegen_inner(
+    module: &mut Module<impl Backend + 'static>,
+    unwind_context: &mut UnwindContext<'_>,
+    kind: AllocatorKind,
+) {
     let usize_ty = module.target_config().pointer_type();
 
     for method in ALLOCATOR_METHODS {
@@ -99,5 +107,6 @@ fn codegen_inner(module: &mut Module<impl Backend + 'static>, kind: AllocatorKin
             &mut ctx,
             &mut cranelift_codegen::binemit::NullTrapSink {},
         ).unwrap();
+        unwind_context.add_function(func_id, &ctx, module.isa());
     }
 }

src/driver/aot.rs

@@ -123,7 +123,7 @@ fn module_codegen(tcx: TyCtxt<'_>, cgu_name: rustc_span::Symbol) -> ModuleCodege
     let mut unwind_context = UnwindContext::new(tcx, &mut module);
 
     super::codegen_mono_items(tcx, &mut module, debug.as_mut(), &mut unwind_context, mono_items);
-    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut module);
+    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut module, &mut unwind_context);
 
     emit_module(
         tcx,
@@ -185,19 +185,21 @@ pub(super) fn run_aot(
     tcx.sess.abort_if_errors();
 
     let mut allocator_module = new_module(tcx, "allocator_shim".to_string());
-    let created_alloc_shim = crate::allocator::codegen(tcx, &mut allocator_module);
+    let mut allocator_unwind_context = UnwindContext::new(tcx, &mut allocator_module);
+    let created_alloc_shim = crate::allocator::codegen(
+        tcx,
+        &mut allocator_module,
+        &mut allocator_unwind_context,
+    );
 
     let allocator_module = if created_alloc_shim {
-        // FIXME create .eh_frame for allocator shim
-        let unwind_context = UnwindContext::new(tcx, &mut allocator_module);
-
         let ModuleCodegenResult(module, work_product) = emit_module(
             tcx,
             "allocator_shim".to_string(),
             ModuleKind::Allocator,
             allocator_module,
             None,
-            unwind_context,
+            allocator_unwind_context,
         );
         if let Some((id, product)) = work_product {
             work_products.insert(id, product);

src/driver/jit.rs

@@ -57,8 +57,8 @@ pub(super) fn run_jit(tcx: TyCtxt<'_>) -> ! {
     super::time(tcx, "codegen mono items", || {
         super::codegen_mono_items(tcx, &mut jit_module, None, &mut unwind_context, mono_items);
     });
-    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut jit_module);
-    crate::allocator::codegen(tcx, &mut jit_module);
+    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut jit_module, &mut unwind_context);
+    crate::allocator::codegen(tcx, &mut jit_module, &mut unwind_context);
 
     jit_module.finalize_definitions();
 

src/main_shim.rs

@@ -2,7 +2,11 @@ use crate::prelude::*;
 
 /// Create the `main` function which will initialize the rust runtime and call
 /// users main function.
-pub(crate) fn maybe_create_entry_wrapper(tcx: TyCtxt<'_>, module: &mut Module<impl Backend + 'static>) {
+pub(crate) fn maybe_create_entry_wrapper(
+    tcx: TyCtxt<'_>,
+    module: &mut Module<impl Backend + 'static>,
+    unwind_context: &mut UnwindContext<'_>,
+) {
     use rustc_hir::lang_items::StartFnLangItem;
     use rustc_session::config::EntryFnType;
 
@@ -22,11 +26,12 @@ pub(crate) fn maybe_create_entry_wrapper(tcx: TyCtxt<'_>, module: &mut Module<im
         return;
     }
 
-    create_entry_fn(tcx, module, main_def_id, use_start_lang_item);
+    create_entry_fn(tcx, module, unwind_context, main_def_id, use_start_lang_item);
 
     fn create_entry_fn(
         tcx: TyCtxt<'_>,
         m: &mut Module<impl Backend + 'static>,
+        unwind_context: &mut UnwindContext<'_>,
         rust_main_def_id: DefId,
         use_start_lang_item: bool,
     ) {
@@ -109,5 +114,6 @@ pub(crate) fn maybe_create_entry_wrapper(tcx: TyCtxt<'_>, module: &mut Module<im
             &mut ctx,
             &mut cranelift_codegen::binemit::NullTrapSink {},
         ).unwrap();
+        unwind_context.add_function(cmain_func_id, &ctx, m.isa());
     }
 }