6 files changed, 33 insertions, 5 deletions
diff --git a/compiler/rustc_codegen_llvm/src/allocator.rs b/compiler/rustc_codegen_llvm/src/allocator.rs
index 30d91b41a8e..7680d4fd233 100644
--- a/compiler/rustc_codegen_llvm/src/allocator.rs
+++ b/compiler/rustc_codegen_llvm/src/allocator.rs
@@ -64,7 +64,7 @@ pub(crate) unsafe fn codegen(
             llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
         }
         if tcx.sess.must_emit_unwind_tables() {
-            attributes::emit_uwtable(llfn, true);
+            attributes::emit_uwtable(llfn);
         }
 
         let callee = kind.fn_name(method.name);
@@ -111,7 +111,7 @@ pub(crate) unsafe fn codegen(
         llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
     }
     if tcx.sess.must_emit_unwind_tables() {
-        attributes::emit_uwtable(llfn, true);
+        attributes::emit_uwtable(llfn);
     }
 
     let kind = if has_alloc_error_handler { AllocatorKind::Global } else { AllocatorKind::Default };
diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 2472789601e..30a52d6bd67 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -59,8 +59,11 @@ pub fn sanitize<'ll>(cx: &CodegenCx<'ll, '_>, no_sanitize: SanitizerSet, llfn: &
 
 /// Tell LLVM to emit or not emit the information necessary to unwind the stack for the function.
 #[inline]
-pub fn emit_uwtable(val: &Value, emit: bool) {
-    Attribute::UWTable.toggle_llfn(Function, val, emit);
+pub fn emit_uwtable(val: &Value) {
+    // NOTE: We should determine if we even need async unwind tables, as they
+    // take have more overhead and if we can use sync unwind tables we
+    // probably should.
+    llvm::EmitUWTableAttr(val, true);
 }
 
 /// Tell LLVM if this function should be 'naked', i.e., skip the epilogue and prologue.
@@ -275,7 +278,7 @@ pub fn from_fn_attrs<'ll, 'tcx>(
     // You can also find more info on why Windows always requires uwtables here:
     //      https://bugzilla.mozilla.org/show_bug.cgi?id=1302078
     if cx.sess().must_emit_unwind_tables() {
-        attributes::emit_uwtable(llfn, true);
+        attributes::emit_uwtable(llfn);
     }
 
     if cx.sess().opts.debugging_opts.profile_sample_use.is_some() {
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 4f62c685568..90d4367a280 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -1182,6 +1182,7 @@ extern "C" {
     pub fn LLVMRustAddByValAttr(Fn: &Value, index: c_uint, ty: &Type);
     pub fn LLVMRustAddStructRetAttr(Fn: &Value, index: c_uint, ty: &Type);
     pub fn LLVMRustAddFunctionAttribute(Fn: &Value, index: c_uint, attr: Attribute);
+    pub fn LLVMRustEmitUWTableAttr(Fn: &Value, async_: bool);
     pub fn LLVMRustAddFunctionAttrStringValue(
         Fn: &Value,
         index: c_uint,
diff --git a/compiler/rustc_codegen_llvm/src/llvm/mod.rs b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
index a1117a11fc7..8586b0466c8 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
@@ -31,6 +31,10 @@ impl LLVMRustResult {
     }
 }
 
+pub fn EmitUWTableAttr(llfn: &Value, async_: bool) {
+    unsafe { LLVMRustEmitUWTableAttr(llfn, async_) }
+}
+
 pub fn AddFunctionAttrStringValue(llfn: &Value, idx: AttributePlace, attr: &CStr, value: &CStr) {
     unsafe {
         LLVMRustAddFunctionAttrStringValue(llfn, idx.as_uint(), attr.as_ptr(), value.as_ptr())
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index fb9c5e6a527..23333199506 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -334,6 +334,17 @@ extern "C" void LLVMRustAddStructRetAttr(LLVMValueRef Fn, unsigned Index,
   AddAttribute(F, Index, Attr);
 }
 
+extern "C" void LLVMRustEmitUWTableAttr(LLVMValueRef Fn, bool Async) {
+  Function *F = unwrap<Function>(Fn);
+#if LLVM_VERSION_LT(15, 0)
+  Attribute Attr = Attribute::get(F->getContext(), Attribute::UWTable);
+#else
+  Attribute Attr = Attribute::getWithUWTableKind(
+      F->getContext(), Async ? UWTableKind::Async : UWTableKind::Sync);
+#endif
+  AddAttribute(F, AttributeList::AttrIndex::FunctionIndex, Attr);
+}
+
 extern "C" void LLVMRustAddFunctionAttrStringValue(LLVMValueRef Fn,
                                                    unsigned Index,
                                                    const char *Name,
diff --git a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
index 7f68112a427..a41956c58f0 100644
--- a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
+++ b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
@@ -185,6 +185,15 @@ pub(crate) fn emit_unescape_error(
                      version control settings",
                 );
             } else {
+                if !mode.is_bytes() {
+                    diag.span_suggestion(
+                        span_with_quotes,
+                        "if you meant to write a literal backslash (perhaps escaping in a regular expression), consider a raw string literal",
+                        format!("r\"{}\"", lit),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+
                 diag.help(
                     "for more information, visit \
                      <https://static.rust-lang.org/doc/master/reference.html#literals>",