various fixes for naked_asm! implementation

- fix for divergence
- fix error message
- fix another cranelift test
- fix some cranelift things
- don't set the NORETURN option for naked asm
- fix use of naked_asm! in doc comment
- fix use of naked_asm! in run-make test
- use `span_bug` in unreachable branch

compiler/rustc_middle/src/mir/pretty.rs

@@ -4,7 +4,7 @@ use std::fs;
 use std::io::{self, Write as _};
 use std::path::{Path, PathBuf};
 
-use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
+use rustc_ast::InlineAsmTemplatePiece;
 use rustc_middle::mir::interpret::{
     AllocBytes, AllocId, Allocation, GlobalAlloc, Pointer, Provenance, alloc_range,
     read_target_uint,
@@ -1024,9 +1024,9 @@ impl<'tcx> TerminatorKind<'tcx> {
                 vec!["real".into(), "unwind".into()]
             }
             FalseUnwind { unwind: _, .. } => vec!["real".into()],
-            InlineAsm { options, ref targets, unwind, .. } => {
+            InlineAsm { asm_macro, options, ref targets, unwind, .. } => {
                 let mut vec = Vec::with_capacity(targets.len() + 1);
-                if !options.contains(InlineAsmOptions::NORETURN) {
+                if !asm_macro.diverges(options) {
                     vec.push("return".into());
                 }
                 vec.resize(targets.len(), "label".into());

compiler/rustc_middle/src/mir/syntax.rs

@@ -605,6 +605,25 @@ impl CallSource {
     }
 }
 
+#[derive(Clone, Copy, Debug, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
+#[derive(TypeFoldable, TypeVisitable)]
+/// The macro that an inline assembly block was created by
+pub enum InlineAsmMacro {
+    /// The `asm!` macro
+    Asm,
+    /// The `naked_asm!` macro
+    NakedAsm,
+}
+
+impl InlineAsmMacro {
+    pub const fn diverges(self, options: InlineAsmOptions) -> bool {
+        match self {
+            InlineAsmMacro::Asm => options.contains(InlineAsmOptions::NORETURN),
+            InlineAsmMacro::NakedAsm => true,
+        }
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////
 // Terminators
 
@@ -859,6 +878,9 @@ pub enum TerminatorKind<'tcx> {
     /// Block ends with an inline assembly block. This is a terminator since
     /// inline assembly is allowed to diverge.
     InlineAsm {
+        /// Macro used to create this inline asm: one of `asm!` or `naked_asm!`
+        asm_macro: InlineAsmMacro,
+
         /// The template for the inline assembly, with placeholders.
         template: &'tcx [InlineAsmTemplatePiece],
 
@@ -874,7 +896,7 @@ pub enum TerminatorKind<'tcx> {
 
         /// Valid targets for the inline assembly.
         /// The first element is the fallthrough destination, unless
-        /// InlineAsmOptions::NORETURN is set.
+        /// asm_macro == InlineAsmMacro::NakedAsm or InlineAsmOptions::NORETURN is set.
         targets: Box<[BasicBlock]>,
 
         /// Action to be taken if the inline assembly unwinds. This is present

compiler/rustc_middle/src/mir/terminator.rs

@@ -666,6 +666,7 @@ impl<'tcx> TerminatorKind<'tcx> {
             },
 
             InlineAsm {
+                asm_macro: _,
                 template: _,
                 ref operands,
                 options: _,

compiler/rustc_middle/src/mir/visit.rs

@@ -576,6 +576,7 @@ macro_rules! make_mir_visitor {
                     }
 
                     TerminatorKind::InlineAsm {
+                        asm_macro: _,
                         template: _,
                         operands,
                         options: _,

compiler/rustc_middle/src/thir.rs

@@ -12,7 +12,7 @@ use std::cmp::Ordering;
 use std::fmt;
 use std::ops::Index;
 
-use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
+use rustc_ast::{AsmMacro, InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{BindingMode, ByRef, HirId, MatchSource, RangeEnd};
@@ -173,6 +173,7 @@ pub struct ClosureExpr<'tcx> {
 
 #[derive(Clone, Debug, HashStable)]
 pub struct InlineAsmExpr<'tcx> {
+    pub asm_macro: AsmMacro,
     pub template: &'tcx [InlineAsmTemplatePiece],
     pub operands: Box<[InlineAsmOperand<'tcx>]>,
     pub options: InlineAsmOptions,

compiler/rustc_middle/src/thir/visit.rs

@@ -148,7 +148,13 @@ pub fn walk_expr<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
         NamedConst { def_id: _, args: _, user_ty: _ } => {}
         ConstParam { param: _, def_id: _ } => {}
         StaticRef { alloc_id: _, ty: _, def_id: _ } => {}
-        InlineAsm(box InlineAsmExpr { ref operands, template: _, options: _, line_spans: _ }) => {
+        InlineAsm(box InlineAsmExpr {
+            asm_macro: _,
+            ref operands,
+            template: _,
+            options: _,
+            line_spans: _,
+        }) => {
             for op in &**operands {
                 use InlineAsmOperand::*;
                 match op {