1 files changed, 135 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/abi/comments.rs b/compiler/rustc_codegen_cranelift/src/abi/comments.rs
new file mode 100644
index 000000000..37d2679c1
--- /dev/null
+++ b/compiler/rustc_codegen_cranelift/src/abi/comments.rs
@@ -0,0 +1,135 @@
+//! Annotate the clif ir with comments describing how arguments are passed into the current function
+//! and where all locals are stored.
+
+use std::borrow::Cow;
+
+use rustc_middle::mir;
+use rustc_target::abi::call::PassMode;
+
+use cranelift_codegen::entity::EntityRef;
+
+use crate::prelude::*;
+
+pub(super) fn add_args_header_comment(fx: &mut FunctionCx<'_, '_, '_>) {
+    if fx.clif_comments.enabled() {
+        fx.add_global_comment(
+            "kind  loc.idx   param    pass mode                            ty".to_string(),
+        );
+    }
+}
+
+pub(super) fn add_arg_comment<'tcx>(
+    fx: &mut FunctionCx<'_, '_, 'tcx>,
+    kind: &str,
+    local: Option<mir::Local>,
+    local_field: Option<usize>,
+    params: &[Value],
+    arg_abi_mode: PassMode,
+    arg_layout: TyAndLayout<'tcx>,
+) {
+    if !fx.clif_comments.enabled() {
+        return;
+    }
+
+    let local = if let Some(local) = local {
+        Cow::Owned(format!("{:?}", local))
+    } else {
+        Cow::Borrowed("???")
+    };
+    let local_field = if let Some(local_field) = local_field {
+        Cow::Owned(format!(".{}", local_field))
+    } else {
+        Cow::Borrowed("")
+    };
+
+    let params = match params {
+        [] => Cow::Borrowed("-"),
+        [param] => Cow::Owned(format!("= {:?}", param)),
+        [param_a, param_b] => Cow::Owned(format!("= {:?},{:?}", param_a, param_b)),
+        params => Cow::Owned(format!(
+            "= {}",
+            params.iter().map(ToString::to_string).collect::<Vec<_>>().join(",")
+        )),
+    };
+
+    let pass_mode = format!("{:?}", arg_abi_mode);
+    fx.add_global_comment(format!(
+        "{kind:5}{local:>3}{local_field:<5} {params:10} {pass_mode:36} {ty:?}",
+        kind = kind,
+        local = local,
+        local_field = local_field,
+        params = params,
+        pass_mode = pass_mode,
+        ty = arg_layout.ty,
+    ));
+}
+
+pub(super) fn add_locals_header_comment(fx: &mut FunctionCx<'_, '_, '_>) {
+    if fx.clif_comments.enabled() {
+        fx.add_global_comment(String::new());
+        fx.add_global_comment(
+            "kind  local ty                              size align (abi,pref)".to_string(),
+        );
+    }
+}
+
+pub(super) fn add_local_place_comments<'tcx>(
+    fx: &mut FunctionCx<'_, '_, 'tcx>,
+    place: CPlace<'tcx>,
+    local: Local,
+) {
+    if !fx.clif_comments.enabled() {
+        return;
+    }
+    let TyAndLayout { ty, layout } = place.layout();
+    let rustc_target::abi::LayoutS {
+        size,
+        align,
+        abi: _,
+        variants: _,
+        fields: _,
+        largest_niche: _,
+    } = layout.0.0;
+
+    let (kind, extra) = match *place.inner() {
+        CPlaceInner::Var(place_local, var) => {
+            assert_eq!(local, place_local);
+            ("ssa", Cow::Owned(format!(",var={}", var.index())))
+        }
+        CPlaceInner::VarPair(place_local, var1, var2) => {
+            assert_eq!(local, place_local);
+            ("ssa", Cow::Owned(format!(",var=({}, {})", var1.index(), var2.index())))
+        }
+        CPlaceInner::VarLane(_local, _var, _lane) => unreachable!(),
+        CPlaceInner::Addr(ptr, meta) => {
+            let meta = if let Some(meta) = meta {
+                Cow::Owned(format!(",meta={}", meta))
+            } else {
+                Cow::Borrowed("")
+            };
+            match ptr.debug_base_and_offset() {
+                (crate::pointer::PointerBase::Addr(addr), offset) => {
+                    ("reuse", format!("storage={}{}{}", addr, offset, meta).into())
+                }
+                (crate::pointer::PointerBase::Stack(stack_slot), offset) => {
+                    ("stack", format!("storage={}{}{}", stack_slot, offset, meta).into())
+                }
+                (crate::pointer::PointerBase::Dangling(align), offset) => {
+                    ("zst", format!("align={},offset={}", align.bytes(), offset).into())
+                }
+            }
+        }
+    };
+
+    fx.add_global_comment(format!(
+        "{:<5} {:5} {:30} {:4}b {}, {}{}{}",
+        kind,
+        format!("{:?}", local),
+        format!("{:?}", ty),
+        size.bytes(),
+        align.abi.bytes(),
+        align.pref.bytes(),
+        if extra.is_empty() { "" } else { "              " },
+        extra,
+    ));
+}