From 484152d562f6babaacb3fae08cc5f70ee550e9ee Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Thu, 15 Feb 2024 19:54:37 +0000
Subject: Support tail calls in mir via `TerminatorKind::TailCall`

---
 compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs  | 1 +
 compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs | 2 ++
 compiler/rustc_mir_dataflow/src/move_paths/builder.rs     | 6 ++++++
 compiler/rustc_mir_dataflow/src/value_analysis.rs         | 3 +++
 4 files changed, 12 insertions(+)

(limited to 'compiler/rustc_mir_dataflow/src')

diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 706bb796349..574da949b0e 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -145,6 +145,7 @@ where
             | TerminatorKind::InlineAsm { .. }
             | TerminatorKind::UnwindResume
             | TerminatorKind::Return
+            | TerminatorKind::TailCall { .. }
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::Unreachable
             | TerminatorKind::Yield { .. } => {}
diff --git a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
index 29169c31263..f850a710277 100644
--- a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
@@ -288,6 +288,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
             | TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
             | TerminatorKind::Return
+            | TerminatorKind::TailCall { .. }
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::Unreachable => {}
         }
@@ -325,6 +326,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
             | TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
             | TerminatorKind::Return
+            | TerminatorKind::TailCall { .. }
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::Unreachable => {}
         }
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
index 1fb77bef3d4..7b39db821d8 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -489,6 +489,12 @@ impl<'b, 'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> Gatherer<'b, 'a, 'tcx, F> {
                     self.gather_init(destination.as_ref(), InitKind::NonPanicPathOnly);
                 }
             }
+            TerminatorKind::TailCall { ref func, ref args, .. } => {
+                self.gather_operand(func);
+                for arg in args {
+                    self.gather_operand(&arg.node);
+                }
+            }
             TerminatorKind::InlineAsm {
                 template: _,
                 ref operands,
diff --git a/compiler/rustc_mir_dataflow/src/value_analysis.rs b/compiler/rustc_mir_dataflow/src/value_analysis.rs
index 7c1ff6fda53..1582c2e8a90 100644
--- a/compiler/rustc_mir_dataflow/src/value_analysis.rs
+++ b/compiler/rustc_mir_dataflow/src/value_analysis.rs
@@ -269,6 +269,9 @@ pub trait ValueAnalysis<'tcx> {
             TerminatorKind::SwitchInt { discr, targets } => {
                 return self.handle_switch_int(discr, targets, state);
             }
+            TerminatorKind::TailCall { .. } => {
+                // FIXME(explicit_tail_calls): determine if we need to do something here (probably not)
+            }
             TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
             | TerminatorKind::UnwindTerminate(_)
-- 
cgit 1.4.1-3-g733a5