Add a few dest-prop MIR tests

8 files changed, 362 insertions, 0 deletions

diff --git a/src/test/mir-opt/dest-prop/branch.rs b/src/test/mir-opt/dest-prop/branch.rs
new file mode 100644
index 00000000000..b49ecf07daa
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/branch.rs
@@ -0,0 +1,21 @@
+//! Tests that assignment in both branches of an `if` are eliminated.
+
+fn val() -> i32 {
+    1
+}
+
+fn cond() -> bool {
+    true
+}
+
+// EMIT_MIR rustc.main.DestinationPropagation.diff
+fn main() {
+    let x = val();
+
+    let y = if cond() {
+        x
+    } else {
+        val();
+        x
+    };
+}
diff --git a/src/test/mir-opt/dest-prop/branch/rustc.main.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/branch/rustc.main.DestinationPropagation.diff
new file mode 100644
index 00000000000..b8387ae4493
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/branch/rustc.main.DestinationPropagation.diff
@@ -0,0 +1,88 @@
+- // MIR for `main` before DestinationPropagation
++ // MIR for `main` after DestinationPropagation
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/branch.rs:12:11: 12:11
+      let _1: i32;                         // in scope 0 at $DIR/branch.rs:13:9: 13:10
+      let mut _3: bool;                    // in scope 0 at $DIR/branch.rs:15:16: 15:22
+      let _4: i32;                         // in scope 0 at $DIR/branch.rs:18:9: 18:14
+      scope 1 {
+-         debug x => _1;                   // in scope 1 at $DIR/branch.rs:13:9: 13:10
++         debug x => _2;                   // in scope 1 at $DIR/branch.rs:13:9: 13:10
+          let _2: i32;                     // in scope 1 at $DIR/branch.rs:15:9: 15:10
+          scope 2 {
+              debug y => _2;               // in scope 2 at $DIR/branch.rs:15:9: 15:10
+          }
+      }
+  
+      bb0: {
+-         StorageLive(_1);                 // scope 0 at $DIR/branch.rs:13:9: 13:10
+-         _1 = const val() -> bb1;         // scope 0 at $DIR/branch.rs:13:13: 13:18
++         nop;                             // scope 0 at $DIR/branch.rs:13:9: 13:10
++         _2 = const val() -> bb1;         // scope 0 at $DIR/branch.rs:13:13: 13:18
+                                           // ty::Const
+                                           // + ty: fn() -> i32 {val}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/branch.rs:13:13: 13:16
+                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb1: {
+-         StorageLive(_2);                 // scope 1 at $DIR/branch.rs:15:9: 15:10
++         nop;                             // scope 1 at $DIR/branch.rs:15:9: 15:10
+          StorageLive(_3);                 // scope 1 at $DIR/branch.rs:15:16: 15:22
+          _3 = const cond() -> bb2;        // scope 1 at $DIR/branch.rs:15:16: 15:22
+                                           // ty::Const
+                                           // + ty: fn() -> bool {cond}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/branch.rs:15:16: 15:20
+                                           // + literal: Const { ty: fn() -> bool {cond}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb2: {
+          switchInt(_3) -> [false: bb3, otherwise: bb4]; // scope 1 at $DIR/branch.rs:15:13: 20:6
+      }
+  
+      bb3: {
+          StorageLive(_4);                 // scope 1 at $DIR/branch.rs:18:9: 18:14
+          _4 = const val() -> bb5;         // scope 1 at $DIR/branch.rs:18:9: 18:14
+                                           // ty::Const
+                                           // + ty: fn() -> i32 {val}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/branch.rs:18:9: 18:12
+                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb4: {
+-         _2 = _1;                         // scope 1 at $DIR/branch.rs:16:9: 16:10
++         nop;                             // scope 1 at $DIR/branch.rs:16:9: 16:10
+          goto -> bb6;                     // scope 1 at $DIR/branch.rs:15:13: 20:6
+      }
+  
+      bb5: {
+          StorageDead(_4);                 // scope 1 at $DIR/branch.rs:18:14: 18:15
+-         _2 = _1;                         // scope 1 at $DIR/branch.rs:19:9: 19:10
++         nop;                             // scope 1 at $DIR/branch.rs:19:9: 19:10
+          goto -> bb6;                     // scope 1 at $DIR/branch.rs:15:13: 20:6
+      }
+  
+      bb6: {
+          StorageDead(_3);                 // scope 1 at $DIR/branch.rs:20:6: 20:7
+          _0 = const ();                   // scope 0 at $DIR/branch.rs:12:11: 21:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/branch.rs:12:11: 21:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+-         StorageDead(_2);                 // scope 1 at $DIR/branch.rs:21:1: 21:2
+-         StorageDead(_1);                 // scope 0 at $DIR/branch.rs:21:1: 21:2
++         nop;                             // scope 1 at $DIR/branch.rs:21:1: 21:2
++         nop;                             // scope 0 at $DIR/branch.rs:21:1: 21:2
+          return;                          // scope 0 at $DIR/branch.rs:21:2: 21:2
+      }
+  }
+  
diff --git a/src/test/mir-opt/dest-prop/cycle.rs b/src/test/mir-opt/dest-prop/cycle.rs
new file mode 100644
index 00000000000..d55d527bc65
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/cycle.rs
@@ -0,0 +1,15 @@
+//! Tests that cyclic assignments don't hang DestinationPropagation, and result in reasonable code.
+
+fn val() -> i32 {
+    1
+}
+
+// EMIT_MIR rustc.main.DestinationPropagation.diff
+fn main() {
+    let mut x = val();
+    let y = x;
+    let z = y;
+    x = z;
+
+    drop(x);
+}
diff --git a/src/test/mir-opt/dest-prop/cycle/rustc.main.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/cycle/rustc.main.DestinationPropagation.diff
new file mode 100644
index 00000000000..5189b665acf
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/cycle/rustc.main.DestinationPropagation.diff
@@ -0,0 +1,91 @@
+- // MIR for `main` before DestinationPropagation
++ // MIR for `main` after DestinationPropagation
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/cycle.rs:8:11: 8:11
+      let mut _1: i32;                     // in scope 0 at $DIR/cycle.rs:9:9: 9:14
+      let mut _4: i32;                     // in scope 0 at $DIR/cycle.rs:12:9: 12:10
+      let _5: ();                          // in scope 0 at $DIR/cycle.rs:14:5: 14:12
+      let mut _6: i32;                     // in scope 0 at $DIR/cycle.rs:14:10: 14:11
+      scope 1 {
+-         debug x => _1;                   // in scope 1 at $DIR/cycle.rs:9:9: 9:14
++         debug x => _4;                   // in scope 1 at $DIR/cycle.rs:9:9: 9:14
+          let _2: i32;                     // in scope 1 at $DIR/cycle.rs:10:9: 10:10
+          scope 2 {
+-             debug y => _2;               // in scope 2 at $DIR/cycle.rs:10:9: 10:10
++             debug y => _4;               // in scope 2 at $DIR/cycle.rs:10:9: 10:10
+              let _3: i32;                 // in scope 2 at $DIR/cycle.rs:11:9: 11:10
+              scope 3 {
+-                 debug z => _3;           // in scope 3 at $DIR/cycle.rs:11:9: 11:10
++                 debug z => _4;           // in scope 3 at $DIR/cycle.rs:11:9: 11:10
+                  scope 4 {
+                      debug _x => _6;      // in scope 4 at $SRC_DIR/libcore/mem/mod.rs:LL:COL
+                  }
+              }
+          }
+      }
+  
+      bb0: {
+-         StorageLive(_1);                 // scope 0 at $DIR/cycle.rs:9:9: 9:14
+-         _1 = const val() -> bb1;         // scope 0 at $DIR/cycle.rs:9:17: 9:22
++         nop;                             // scope 0 at $DIR/cycle.rs:9:9: 9:14
++         _4 = const val() -> bb1;         // scope 0 at $DIR/cycle.rs:9:17: 9:22
+                                           // ty::Const
+                                           // + ty: fn() -> i32 {val}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/cycle.rs:9:17: 9:20
+                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb1: {
+-         StorageLive(_2);                 // scope 1 at $DIR/cycle.rs:10:9: 10:10
+-         _2 = _1;                         // scope 1 at $DIR/cycle.rs:10:13: 10:14
+-         StorageLive(_3);                 // scope 2 at $DIR/cycle.rs:11:9: 11:10
+-         _3 = _2;                         // scope 2 at $DIR/cycle.rs:11:13: 11:14
+-         StorageLive(_4);                 // scope 3 at $DIR/cycle.rs:12:9: 12:10
+-         _4 = _3;                         // scope 3 at $DIR/cycle.rs:12:9: 12:10
+-         _1 = move _4;                    // scope 3 at $DIR/cycle.rs:12:5: 12:10
+-         StorageDead(_4);                 // scope 3 at $DIR/cycle.rs:12:9: 12:10
++         nop;                             // scope 1 at $DIR/cycle.rs:10:9: 10:10
++         nop;                             // scope 1 at $DIR/cycle.rs:10:13: 10:14
++         nop;                             // scope 2 at $DIR/cycle.rs:11:9: 11:10
++         nop;                             // scope 2 at $DIR/cycle.rs:11:13: 11:14
++         nop;                             // scope 3 at $DIR/cycle.rs:12:9: 12:10
++         nop;                             // scope 3 at $DIR/cycle.rs:12:9: 12:10
++         nop;                             // scope 3 at $DIR/cycle.rs:12:5: 12:10
++         nop;                             // scope 3 at $DIR/cycle.rs:12:9: 12:10
+          StorageLive(_5);                 // scope 3 at $DIR/cycle.rs:14:5: 14:12
+          StorageLive(_6);                 // scope 3 at $DIR/cycle.rs:14:10: 14:11
+-         _6 = _1;                         // scope 3 at $DIR/cycle.rs:14:10: 14:11
++         _6 = _4;                         // scope 3 at $DIR/cycle.rs:14:10: 14:11
+          _5 = const ();                   // scope 4 at $SRC_DIR/libcore/mem/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/mem/mod.rs:LL:COL
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          drop(_6) -> bb2;                 // scope 4 at $SRC_DIR/libcore/mem/mod.rs:LL:COL
+      }
+  
+      bb2: {
+          StorageDead(_6);                 // scope 3 at $DIR/cycle.rs:14:11: 14:12
+          StorageDead(_5);                 // scope 3 at $DIR/cycle.rs:14:12: 14:13
+          _0 = const ();                   // scope 0 at $DIR/cycle.rs:8:11: 15:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/cycle.rs:8:11: 15:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+-         StorageDead(_3);                 // scope 2 at $DIR/cycle.rs:15:1: 15:2
+-         StorageDead(_2);                 // scope 1 at $DIR/cycle.rs:15:1: 15:2
+-         StorageDead(_1);                 // scope 0 at $DIR/cycle.rs:15:1: 15:2
++         nop;                             // scope 2 at $DIR/cycle.rs:15:1: 15:2
++         nop;                             // scope 1 at $DIR/cycle.rs:15:1: 15:2
++         nop;                             // scope 0 at $DIR/cycle.rs:15:1: 15:2
+          return;                          // scope 0 at $DIR/cycle.rs:15:2: 15:2
+      }
+  }
+  
diff --git a/src/test/mir-opt/dest-prop/simple.rs b/src/test/mir-opt/dest-prop/simple.rs
new file mode 100644
index 00000000000..add821eafe0
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/simple.rs
@@ -0,0 +1,14 @@
+//! Copy of `nrvo-simple.rs`, to ensure that full dest-prop handles it too.
+
+// EMIT_MIR rustc.nrvo.DestinationPropagation.diff
+fn nrvo(init: fn(&mut [u8; 1024])) -> [u8; 1024] {
+    let mut buf = [0; 1024];
+    init(&mut buf);
+    buf
+}
+
+fn main() {
+    let _ = nrvo(|buf| {
+        buf[4] = 4;
+    });
+}
diff --git a/src/test/mir-opt/dest-prop/simple/rustc.nrvo.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/simple/rustc.nrvo.DestinationPropagation.diff
new file mode 100644
index 00000000000..d59e1f3c0c9
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/simple/rustc.nrvo.DestinationPropagation.diff
@@ -0,0 +1,56 @@
+- // MIR for `nrvo` before DestinationPropagation
++ // MIR for `nrvo` after DestinationPropagation
+  
+  fn nrvo(_1: for<'r> fn(&'r mut [u8; 1024])) -> [u8; 1024] {
+      debug init => _1;                    // in scope 0 at $DIR/simple.rs:4:9: 4:13
+      let mut _0: [u8; 1024];              // return place in scope 0 at $DIR/simple.rs:4:39: 4:49
+      let mut _2: [u8; 1024];              // in scope 0 at $DIR/simple.rs:5:9: 5:16
+      let _3: ();                          // in scope 0 at $DIR/simple.rs:6:5: 6:19
+      let mut _4: for<'r> fn(&'r mut [u8; 1024]); // in scope 0 at $DIR/simple.rs:6:5: 6:9
+      let mut _5: &mut [u8; 1024];         // in scope 0 at $DIR/simple.rs:6:10: 6:18
+      let mut _6: &mut [u8; 1024];         // in scope 0 at $DIR/simple.rs:6:10: 6:18
+      scope 1 {
+-         debug buf => _2;                 // in scope 1 at $DIR/simple.rs:5:9: 5:16
++         debug buf => _0;                 // in scope 1 at $DIR/simple.rs:5:9: 5:16
+      }
+  
+      bb0: {
+-         StorageLive(_2);                 // scope 0 at $DIR/simple.rs:5:9: 5:16
+-         _2 = [const 0u8; 1024];          // scope 0 at $DIR/simple.rs:5:19: 5:28
++         nop;                             // scope 0 at $DIR/simple.rs:5:9: 5:16
++         _0 = [const 0u8; 1024];          // scope 0 at $DIR/simple.rs:5:19: 5:28
+                                           // ty::Const
+                                           // + ty: u8
+                                           // + val: Value(Scalar(0x00))
+                                           // mir::Constant
+                                           // + span: $DIR/simple.rs:5:20: 5:21
+                                           // + literal: Const { ty: u8, val: Value(Scalar(0x00)) }
+          StorageLive(_3);                 // scope 1 at $DIR/simple.rs:6:5: 6:19
+          StorageLive(_4);                 // scope 1 at $DIR/simple.rs:6:5: 6:9
+          _4 = _1;                         // scope 1 at $DIR/simple.rs:6:5: 6:9
+-         StorageLive(_5);                 // scope 1 at $DIR/simple.rs:6:10: 6:18
+-         StorageLive(_6);                 // scope 1 at $DIR/simple.rs:6:10: 6:18
+-         _6 = &mut _2;                    // scope 1 at $DIR/simple.rs:6:10: 6:18
+-         _5 = move _6;                    // scope 1 at $DIR/simple.rs:6:10: 6:18
++         nop;                             // scope 1 at $DIR/simple.rs:6:10: 6:18
++         nop;                             // scope 1 at $DIR/simple.rs:6:10: 6:18
++         _5 = &mut _0;                    // scope 1 at $DIR/simple.rs:6:10: 6:18
++         nop;                             // scope 1 at $DIR/simple.rs:6:10: 6:18
+          _3 = move _4(move _5) -> bb1;    // scope 1 at $DIR/simple.rs:6:5: 6:19
+      }
+  
+      bb1: {
+-         StorageDead(_5);                 // scope 1 at $DIR/simple.rs:6:18: 6:19
++         nop;                             // scope 1 at $DIR/simple.rs:6:18: 6:19
+          StorageDead(_4);                 // scope 1 at $DIR/simple.rs:6:18: 6:19
+-         StorageDead(_6);                 // scope 1 at $DIR/simple.rs:6:19: 6:20
++         nop;                             // scope 1 at $DIR/simple.rs:6:19: 6:20
+          StorageDead(_3);                 // scope 1 at $DIR/simple.rs:6:19: 6:20
+-         _0 = _2;                         // scope 1 at $DIR/simple.rs:7:5: 7:8
+-         StorageDead(_2);                 // scope 0 at $DIR/simple.rs:8:1: 8:2
++         nop;                             // scope 1 at $DIR/simple.rs:7:5: 7:8
++         nop;                             // scope 0 at $DIR/simple.rs:8:1: 8:2
+          return;                          // scope 0 at $DIR/simple.rs:8:2: 8:2
+      }
+  }
+  
diff --git a/src/test/mir-opt/dest-prop/union.rs b/src/test/mir-opt/dest-prop/union.rs
new file mode 100644
index 00000000000..ea836412404
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/union.rs
@@ -0,0 +1,16 @@
+//! Tests that projections through unions cancel `DestinationPropagation`.
+
+fn val() -> u32 {
+    1
+}
+
+// EMIT_MIR rustc.main.DestinationPropagation.diff
+fn main() {
+    union Un {
+        us: u32,
+    }
+
+    let un = Un { us: val() };
+
+    drop(unsafe { un.us });
+}
diff --git a/src/test/mir-opt/dest-prop/union/rustc.main.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/union/rustc.main.DestinationPropagation.diff
new file mode 100644
index 00000000000..f6ebb6cb940
--- /dev/null
+++ b/src/test/mir-opt/dest-prop/union/rustc.main.DestinationPropagation.diff
@@ -0,0 +1,61 @@
+- // MIR for `main` before DestinationPropagation
++ // MIR for `main` after DestinationPropagation
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/union.rs:8:11: 8:11
+      let _1: main::Un;                    // in scope 0 at $DIR/union.rs:13:9: 13:11
+      let mut _2: u32;                     // in scope 0 at $DIR/union.rs:13:23: 13:28
+      let _3: ();                          // in scope 0 at $DIR/union.rs:15:5: 15:27
+      let mut _4: u32;                     // in scope 0 at $DIR/union.rs:15:10: 15:26
+      scope 1 {
+          debug un => _1;                  // in scope 1 at $DIR/union.rs:13:9: 13:11
+          scope 2 {
+          }
+          scope 3 {
+              debug _x => _4;              // in scope 3 at $SRC_DIR/libcore/mem/mod.rs:LL:COL
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);                 // scope 0 at $DIR/union.rs:13:9: 13:11
+          StorageLive(_2);                 // scope 0 at $DIR/union.rs:13:23: 13:28
+          _2 = const val() -> bb1;         // scope 0 at $DIR/union.rs:13:23: 13:28
+                                           // ty::Const
+                                           // + ty: fn() -> u32 {val}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/union.rs:13:23: 13:26
+                                           // + literal: Const { ty: fn() -> u32 {val}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb1: {
+          (_1.0: u32) = move _2;           // scope 0 at $DIR/union.rs:13:14: 13:30
+          StorageDead(_2);                 // scope 0 at $DIR/union.rs:13:29: 13:30
+          StorageLive(_3);                 // scope 1 at $DIR/union.rs:15:5: 15:27
+          StorageLive(_4);                 // scope 1 at $DIR/union.rs:15:10: 15:26
+          _4 = (_1.0: u32);                // scope 2 at $DIR/union.rs:15:19: 15:24
+          _3 = const ();                   // scope 3 at $SRC_DIR/libcore/mem/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/mem/mod.rs:LL:COL
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          drop(_4) -> bb2;                 // scope 3 at $SRC_DIR/libcore/mem/mod.rs:LL:COL
+      }
+  
+      bb2: {
+          StorageDead(_4);                 // scope 1 at $DIR/union.rs:15:26: 15:27
+          StorageDead(_3);                 // scope 1 at $DIR/union.rs:15:27: 15:28
+          _0 = const ();                   // scope 0 at $DIR/union.rs:8:11: 16:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/union.rs:8:11: 16:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_1);                 // scope 0 at $DIR/union.rs:16:1: 16:2
+          return;                          // scope 0 at $DIR/union.rs:16:2: 16:2
+      }
+  }
+