Codegen fewer instructions in `mem::replace`

1 files changed, 10 insertions, 22 deletions

diff --git a/tests/mir-opt/pre-codegen/mem_replace.mem_replace.PreCodegen.after.mir b/tests/mir-opt/pre-codegen/mem_replace.mem_replace.PreCodegen.after.mir
index 19e79e0a2f0..50e0538c133 100644
--- a/tests/mir-opt/pre-codegen/mem_replace.mem_replace.PreCodegen.after.mir
+++ b/tests/mir-opt/pre-codegen/mem_replace.mem_replace.PreCodegen.after.mir
@@ -9,29 +9,26 @@ fn mem_replace(_1: &mut u32, _2: u32) -> u32 {
         debug src => _2;                 // in scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         let mut _3: *const u32;          // in scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         let mut _4: *mut u32;            // in scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        let mut _5: u32;                 // in scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         scope 2 {
             scope 3 {
                 debug result => _0;      // in scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
                 scope 7 (inlined std::ptr::write::<u32>) { // at $SRC_DIR/core/src/mem/mod.rs:LL:COL
                     debug dst => _4;     // in scope 7 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                    debug src => _5;     // in scope 7 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                    let mut _7: *const u32; // in scope 7 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                    let _8: &u32;        // in scope 7 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                    let mut _9: *mut u32; // in scope 7 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+                    debug src => _2;     // in scope 7 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+                    let mut _6: *mut u32; // in scope 7 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
                     scope 8 {
                         scope 9 (inlined std::ptr::write::runtime::<u32>) { // at $SRC_DIR/core/src/intrinsics.rs:LL:COL
-                            debug dst => _9; // in scope 9 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+                            debug dst => _6; // in scope 9 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
                         }
                     }
                 }
             }
             scope 4 (inlined std::ptr::read::<u32>) { // at $SRC_DIR/core/src/mem/mod.rs:LL:COL
                 debug src => _3;         // in scope 4 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                let mut _6: *const u32;  // in scope 4 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+                let mut _5: *const u32;  // in scope 4 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
                 scope 5 {
                     scope 6 (inlined std::ptr::read::runtime::<u32>) { // at $SRC_DIR/core/src/intrinsics.rs:LL:COL
-                        debug src => _6; // in scope 6 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+                        debug src => _5; // in scope 6 at $SRC_DIR/core/src/intrinsics.rs:LL:COL
                     }
                 }
             }
@@ -41,24 +38,15 @@ fn mem_replace(_1: &mut u32, _2: u32) -> u32 {
     bb0: {
         StorageLive(_3);                 // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         _3 = &raw const (*_1);           // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        StorageLive(_6);                 // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
+        StorageLive(_5);                 // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         _0 = (*_3);                      // scope 5 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        StorageDead(_6);                 // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
+        StorageDead(_5);                 // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         StorageDead(_3);                 // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         StorageLive(_4);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         _4 = &raw mut (*_1);             // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        StorageLive(_5);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        _5 = _2;                         // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        StorageLive(_9);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        StorageLive(_7);                 // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        StorageLive(_8);                 // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        _8 = &_5;                        // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        _7 = &raw const (*_8);           // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        copy_nonoverlapping(dst = _4, src = move _7, count = const 1_usize); // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        StorageDead(_7);                 // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        StorageDead(_8);                 // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-        StorageDead(_9);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
-        StorageDead(_5);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
+        StorageLive(_6);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
+        (*_4) = _2;                      // scope 8 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+        StorageDead(_6);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         StorageDead(_4);                 // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
         return;                          // scope 0 at $DIR/mem_replace.rs:+2:2: +2:2
     }