Merge pull request #1575 from rust-lang/exception-handling-preparation

Preparations for exception handling support

Author: bjorn3

src/base.rs

@@ -566,7 +566,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                 );
             }
             TerminatorKind::UnwindTerminate(reason) => {
-                codegen_unwind_terminate(fx, source_info, *reason);
+                codegen_unwind_terminate(fx, Some(source_info.span), *reason);
             }
             TerminatorKind::UnwindResume => {
                 // FIXME implement unwinding
@@ -1117,18 +1117,10 @@ pub(crate) fn codegen_panic_nounwind<'tcx>(
 
 pub(crate) fn codegen_unwind_terminate<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
-    source_info: mir::SourceInfo,
+    span: Option<Span>,
     reason: UnwindTerminateReason,
 ) {
-    let args = [];
-
-    codegen_panic_inner(
-        fx,
-        reason.lang_item(),
-        &args,
-        UnwindAction::Terminate(UnwindTerminateReason::Abi),
-        Some(source_info.span),
-    );
+    codegen_panic_inner(fx, reason.lang_item(), &[], UnwindAction::Unreachable, span);
 }
 
 fn codegen_panic_inner<'tcx>(

src/compiler_builtins.rs

@@ -67,5 +67,4 @@ builtin_functions! {
     fn malloc(size: size_t) -> *mut c_void;
     fn realloc(p: *mut c_void, size: size_t) -> *mut c_void;
     fn free(p: *mut c_void) -> ();
-
 }

src/debuginfo/emit.rs

@@ -81,13 +81,36 @@ impl WriterRelocate {
     /// Perform the collected relocations to be usable for JIT usage.
     #[cfg(all(feature = "jit", not(windows)))]
     pub(super) fn relocate_for_jit(mut self, jit_module: &cranelift_jit::JITModule) -> Vec<u8> {
+        use cranelift_module::Module;
+
         for reloc in self.relocs.drain(..) {
             match reloc.name {
                 super::DebugRelocName::Section(_) => unreachable!(),
                 super::DebugRelocName::Symbol(sym) => {
-                    let addr = jit_module.get_finalized_function(
-                        cranelift_module::FuncId::from_u32(sym.try_into().unwrap()),
-                    );
+                    let addr = if sym & 1 << 31 == 0 {
+                        let func_id = FuncId::from_u32(sym.try_into().unwrap());
+                        // FIXME make JITModule::get_address public and use it here instead.
+                        // HACK rust_eh_personality is likely not defined in the same crate,
+                        // so get_finalized_function won't work. Use the rust_eh_personality
+                        // of cg_clif itself, which is likely ABI compatible.
+                        if jit_module.declarations().get_function_decl(func_id).name.as_deref()
+                            == Some("rust_eh_personality")
+                        {
+                            extern "C" {
+                                fn rust_eh_personality() -> !;
+                            }
+                            rust_eh_personality as *const u8
+                        } else {
+                            jit_module.get_finalized_function(func_id)
+                        }
+                    } else {
+                        jit_module
+                            .get_finalized_data(DataId::from_u32(
+                                u32::try_from(sym).unwrap() & !(1 << 31),
+                            ))
+                            .0
+                    };
+
                     let val = (addr as u64 as i64 + reloc.addend) as u64;
                     self.writer.write_udata_at(reloc.offset as usize, val, reloc.size).unwrap();
                 }
@@ -196,6 +219,16 @@ impl Writer for WriterRelocate {
                     });
                     self.write_udata(0, size)
                 }
+                gimli::DW_EH_PE_absptr => {
+                    self.relocs.push(DebugReloc {
+                        offset: self.len() as u32,
+                        size: size.into(),
+                        name: DebugRelocName::Symbol(symbol),
+                        addend,
+                        kind: object::RelocationKind::Absolute,
+                    });
+                    self.write_udata(0, size.into())
+                }
                 _ => Err(gimli::write::Error::UnsupportedPointerEncoding(eh_pe)),
             },
         }

src/driver/jit.rs

@@ -84,7 +84,7 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, jit_args: Vec<String>) -> ! {
 
     tcx.dcx().abort_if_errors();
 
-    jit_module.finalize_definitions();
+    let mut jit_module = jit_module.finalize_definitions();
 
     println!(
         "Rustc codegen cranelift will JIT run the executable, because -Cllvm-args=mode=jit was passed"
@@ -104,7 +104,7 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, jit_args: Vec<String>) -> ! {
         call_conv: jit_module.target_config().default_call_conv,
     };
     let start_func_id = jit_module.declare_function("main", Linkage::Import, &start_sig).unwrap();
-    let finalized_start: *const u8 = jit_module.module.get_finalized_function(start_func_id);
+    let finalized_start: *const u8 = jit_module.get_finalized_function(start_func_id);
 
     let f: extern "C" fn(c_int, *const *const c_char) -> c_int =
         unsafe { ::std::mem::transmute(finalized_start) };

src/unwind_module.rs

@@ -33,13 +33,10 @@ impl UnwindModule<ObjectModule> {
 
 #[cfg(feature = "jit")]
 impl UnwindModule<cranelift_jit::JITModule> {
-    pub(crate) fn finalize_definitions(&mut self) {
+    pub(crate) fn finalize_definitions(mut self) -> cranelift_jit::JITModule {
         self.module.finalize_definitions().unwrap();
-        let prev_unwind_context = std::mem::replace(
-            &mut self.unwind_context,
-            UnwindContext::new(&mut self.module, false),
-        );
-        unsafe { prev_unwind_context.register_jit(&self.module) };
+        unsafe { self.unwind_context.register_jit(&self.module) };
+        self.module
     }
 }