Auto merge of #76123 - tmiasko:inline-args-storage, r=wesleywiser

inliner: Emit storage markers for introduced arg temporaries

When introducing argument temporaries during inlining, emit storage
marker statements just before the assignment and in the beginning of
the return block.

This ensures that such temporaries will not be considered live across
yield points after inlining inside a generator.

Fixes #71793.

Author: bors

compiler/rustc_mir/src/transform/inline.rs

@@ -506,7 +506,7 @@ impl Inliner<'tcx> {
                 let return_block = destination.1;
 
                 // Copy the arguments if needed.
-                let args: Vec<_> = self.make_call_args(args, &callsite, caller_body);
+                let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, return_block);
 
                 let bb_len = caller_body.basic_blocks().len();
                 let mut integrator = Integrator {
@@ -553,6 +553,7 @@ impl Inliner<'tcx> {
         args: Vec<Operand<'tcx>>,
         callsite: &CallSite<'tcx>,
         caller_body: &mut Body<'tcx>,
+        return_block: BasicBlock,
     ) -> Vec<Local> {
         let tcx = self.tcx;
 
@@ -581,8 +582,18 @@ impl Inliner<'tcx> {
         // and the vector is `[closure_ref, tmp0, tmp1, tmp2]`.
         if tcx.is_closure(callsite.callee) {
             let mut args = args.into_iter();
-            let self_ = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
-            let tuple = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
+            let self_ = self.create_temp_if_necessary(
+                args.next().unwrap(),
+                callsite,
+                caller_body,
+                return_block,
+            );
+            let tuple = self.create_temp_if_necessary(
+                args.next().unwrap(),
+                callsite,
+                caller_body,
+                return_block,
+            );
             assert!(args.next().is_none());
 
             let tuple = Place::from(tuple);
@@ -602,13 +613,13 @@ impl Inliner<'tcx> {
                     Operand::Move(tcx.mk_place_field(tuple, Field::new(i), ty.expect_ty()));
 
                 // Spill to a local to make e.g., `tmp0`.
-                self.create_temp_if_necessary(tuple_field, callsite, caller_body)
+                self.create_temp_if_necessary(tuple_field, callsite, caller_body, return_block)
             });
 
             closure_ref_arg.chain(tuple_tmp_args).collect()
         } else {
             args.into_iter()
-                .map(|a| self.create_temp_if_necessary(a, callsite, caller_body))
+                .map(|a| self.create_temp_if_necessary(a, callsite, caller_body, return_block))
                 .collect()
         }
     }
@@ -620,6 +631,7 @@ impl Inliner<'tcx> {
         arg: Operand<'tcx>,
         callsite: &CallSite<'tcx>,
         caller_body: &mut Body<'tcx>,
+        return_block: BasicBlock,
     ) -> Local {
         // FIXME: Analysis of the usage of the arguments to avoid
         // unnecessary temporaries.
@@ -642,11 +654,19 @@ impl Inliner<'tcx> {
         let arg_tmp = LocalDecl::new(ty, callsite.location.span);
         let arg_tmp = caller_body.local_decls.push(arg_tmp);
 
-        let stmt = Statement {
+        caller_body[callsite.bb].statements.push(Statement {
+            source_info: callsite.location,
+            kind: StatementKind::StorageLive(arg_tmp),
+        });
+        caller_body[callsite.bb].statements.push(Statement {
             source_info: callsite.location,
             kind: StatementKind::Assign(box (Place::from(arg_tmp), arg)),
-        };
-        caller_body[callsite.bb].statements.push(stmt);
+        });
+        caller_body[return_block].statements.insert(
+            0,
+            Statement { source_info: callsite.location, kind: StatementKind::StorageDead(arg_tmp) },
+        );
+
         arg_tmp
     }
 }

src/test/mir-opt/inline/inline_any_operand.bar.Inline.after.mir

@@ -22,9 +22,13 @@ fn bar() -> bool {
                                          // + literal: Const { ty: fn(i32, i32) -> bool {foo}, val: Value(Scalar(<ZST>)) }
         StorageLive(_2);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:6
         _2 = _1;                         // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:6
+        StorageLive(_3);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
         _3 = const 1_i32;                // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
+        StorageLive(_4);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
         _4 = const -1_i32;               // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
         _0 = Eq(move _3, move _4);       // scope 2 at $DIR/inline-any-operand.rs:17:5: 17:11
+        StorageDead(_4);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
+        StorageDead(_3);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
         StorageDead(_2);                 // scope 1 at $DIR/inline-any-operand.rs:12:12: 12:13
         StorageDead(_1);                 // scope 0 at $DIR/inline-any-operand.rs:13:1: 13:2
         return;                          // scope 0 at $DIR/inline-any-operand.rs:13:2: 13:2

src/test/mir-opt/inline/inline_closure.foo.Inline.after.mir

@@ -30,9 +30,13 @@ fn foo(_1: T, _2: i32) -> i32 {
         _7 = _2;                         // scope 1 at $DIR/inline-closure.rs:12:10: 12:11
         (_5.0: i32) = move _6;           // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
         (_5.1: i32) = move _7;           // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
+        StorageLive(_8);                 // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
         _8 = move (_5.0: i32);           // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
+        StorageLive(_9);                 // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
         _9 = move (_5.1: i32);           // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
         _0 = _8;                         // scope 2 at $DIR/inline-closure.rs:11:22: 11:24
+        StorageDead(_9);                 // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
+        StorageDead(_8);                 // scope 1 at $DIR/inline-closure.rs:12:5: 12:12
         StorageDead(_7);                 // scope 1 at $DIR/inline-closure.rs:12:11: 12:12
         StorageDead(_6);                 // scope 1 at $DIR/inline-closure.rs:12:11: 12:12
         StorageDead(_5);                 // scope 1 at $DIR/inline-closure.rs:12:11: 12:12

src/test/mir-opt/inline/inline_closure_borrows_arg.foo.Inline.after.mir

@@ -33,9 +33,13 @@ fn foo(_1: T, _2: &i32) -> i32 {
         _7 = &(*_2);                     // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:10: 16:11
         (_5.0: &i32) = move _6;          // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
         (_5.1: &i32) = move _7;          // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
+        StorageLive(_8);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
         _8 = move (_5.0: &i32);          // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
+        StorageLive(_9);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
         _9 = move (_5.1: &i32);          // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
         _0 = (*_8);                      // scope 3 at $DIR/inline-closure-borrows-arg.rs:14:9: 14:18
+        StorageDead(_9);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
+        StorageDead(_8);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
         StorageDead(_7);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12
         StorageDead(_6);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12
         StorageDead(_5);                 // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12

src/test/mir-opt/inline/inline_closure_captures.foo.Inline.after.mir

@@ -38,6 +38,7 @@ fn foo(_1: T, _2: i32) -> (i32, T) {
         StorageLive(_8);                 // scope 1 at $DIR/inline-closure-captures.rs:12:7: 12:8
         _8 = _2;                         // scope 1 at $DIR/inline-closure-captures.rs:12:7: 12:8
         (_7.0: i32) = move _8;           // scope 1 at $DIR/inline-closure-captures.rs:12:5: 12:9
+        StorageLive(_11);                // scope 1 at $DIR/inline-closure-captures.rs:12:5: 12:9
         _11 = move (_7.0: i32);          // scope 1 at $DIR/inline-closure-captures.rs:12:5: 12:9
         StorageLive(_9);                 // scope 2 at $DIR/inline-closure-captures.rs:11:19: 11:20
         _9 = (*((*_6).0: &i32));         // scope 2 at $DIR/inline-closure-captures.rs:11:19: 11:20
@@ -47,6 +48,7 @@ fn foo(_1: T, _2: i32) -> (i32, T) {
         (_0.1: T) = move _10;            // scope 2 at $DIR/inline-closure-captures.rs:11:18: 11:24
         StorageDead(_10);                // scope 2 at $DIR/inline-closure-captures.rs:11:23: 11:24
         StorageDead(_9);                 // scope 2 at $DIR/inline-closure-captures.rs:11:23: 11:24
+        StorageDead(_11);                // scope 1 at $DIR/inline-closure-captures.rs:12:5: 12:9
         StorageDead(_8);                 // scope 1 at $DIR/inline-closure-captures.rs:12:8: 12:9
         StorageDead(_7);                 // scope 1 at $DIR/inline-closure-captures.rs:12:8: 12:9
         StorageDead(_6);                 // scope 1 at $DIR/inline-closure-captures.rs:12:8: 12:9

src/test/ui/mir/issue-71793-inline-args-storage.rs

@@ -0,0 +1,16 @@
+// Verifies that inliner emits StorageLive & StorageDead when introducing
+// temporaries for arguments, so that they don't become part of the generator.
+// Regression test for #71793.
+//
+// check-pass
+// edition:2018
+// compile-args: -Zmir-opt-level=2
+
+#![crate_type = "lib"]
+
+pub async fn connect() {}
+
+pub async fn connect_many() {
+    Vec::<String>::new().first().ok_or("").unwrap();
+    connect().await;
+}