From 563a75b6e3201d200b975cc05b7b32d5ef2e5608 Mon Sep 17 00:00:00 2001
From: Ben Kimock <kimockb@gmail.com>
Date: Fri, 2 Sep 2022 21:22:43 -0400
Subject: [PATCH] Add a Machine hook for inline assembly

---
 compiler/rustc_const_eval/src/interpret/machine.rs  | 10 ++++++++++
 .../rustc_const_eval/src/interpret/terminator.rs    | 13 +++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index 5aabb14fba884..530e252b7c077 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -6,6 +6,7 @@ use std::borrow::{Borrow, Cow};
 use std::fmt::Debug;
 use std::hash::Hash;
 
+use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_middle::mir;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::def_id::DefId;
@@ -323,6 +324,15 @@ pub trait Machine<'mir, 'tcx>: Sized {
         kind: Option<MemoryKind<Self::MemoryKind>>,
     ) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra>>>;
 
+    fn eval_inline_asm(
+        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        _template: &'tcx [InlineAsmTemplatePiece],
+        _operands: &[mir::InlineAsmOperand<'tcx>],
+        _options: InlineAsmOptions,
+    ) -> InterpResult<'tcx> {
+        throw_unsup_format!("inline assembly is not supported")
+    }
+
     /// Hook for performing extra checks on a memory read access.
     ///
     /// Takes read-only access to the allocation so we can keep all the memory read
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index ea366eba77245..50a82aa0e72c9 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -1,5 +1,6 @@
 use std::borrow::Cow;
 
+use rustc_ast::ast::InlineAsmOptions;
 use rustc_middle::ty::layout::{FnAbiOf, LayoutOf};
 use rustc_middle::ty::Instance;
 use rustc_middle::{
@@ -166,8 +167,16 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 terminator.kind
             ),
 
-            // Inline assembly can't be interpreted.
-            InlineAsm { .. } => throw_unsup_format!("inline assembly is not supported"),
+            InlineAsm { template, ref operands, options, destination, .. } => {
+                M::eval_inline_asm(self, template, operands, options)?;
+                if options.contains(InlineAsmOptions::NORETURN) {
+                    throw_ub_format!("returned from noreturn inline assembly");
+                }
+                self.go_to_block(
+                    destination
+                        .expect("InlineAsm terminators without noreturn must have a destination"),
+                )
+            }
         }
 
         Ok(())