- // MIR for `main` before GVN
+ // MIR for `main` after GVN
  
  fn main() -> () {
      let mut _0: ();
      let _1: std::alloc::Layout;
      let mut _2: std::option::Option<std::alloc::Layout>;
      let mut _3: *mut u8;
      let mut _4: *mut [u8];
      let mut _5: std::ptr::NonNull<[u8]>;
      let mut _6: std::result::Result<std::ptr::NonNull<[u8]>, std::alloc::AllocError>;
      let mut _7: &std::alloc::Global;
      let mut _8: std::alloc::Layout;
      scope 1 {
          debug layout => _1;
          let mut _9: &std::alloc::Global;
          scope 2 {
              debug ptr => _3;
          }
          scope 5 (inlined <std::alloc::Global as Allocator>::allocate) {
              debug self => _9;
              debug layout => _8;
          }
          scope 6 (inlined #[track_caller] Result::<NonNull<[u8]>, std::alloc::AllocError>::unwrap) {
              debug self => _6;
              let mut _12: isize;
              let _13: std::alloc::AllocError;
              let mut _14: !;
              let _15: &str;
              let mut _16: &dyn std::fmt::Debug;
              let mut _17: &std::alloc::AllocError;
              scope 7 {
                  debug t => _5;
              }
              scope 8 {
                  debug e => const std::alloc::AllocError;
              }
          }
          scope 9 (inlined NonNull::<[u8]>::as_ptr) {
              debug self => _5;
              let mut _18: *const [u8];
          }
      }
      scope 3 (inlined #[track_caller] Option::<Layout>::unwrap) {
          debug self => _2;
          let mut _10: isize;
          let mut _11: !;
          scope 4 {
              debug val => _1;
          }
      }
  
      bb0: {
-         StorageLive(_1);
+         nop;
          StorageLive(_2);
-         _2 = Option::<Layout>::None;
+         _2 = const Option::<Layout>::None;
          StorageLive(_10);
-         _10 = discriminant(_2);
-         switchInt(move _10) -> [0: bb2, 1: bb3, otherwise: bb1];
+         _10 = const 0_isize;
+         switchInt(const 0_isize) -> [0: bb2, 1: bb3, otherwise: bb1];
      }
  
      bb1: {
          unreachable;
      }
  
      bb2: {
          _11 = option::unwrap_failed() -> unwind unreachable;
      }
  
      bb3: {
-         _1 = move ((_2 as Some).0: std::alloc::Layout);
+         _1 = const Layout {{ size: Indirect { alloc_id: ALLOC0, offset: Size(4 bytes) }: usize, align: std::ptr::Alignment(Scalar(0x00000000): std::ptr::alignment::AlignmentEnum) }};
          StorageDead(_10);
          StorageDead(_2);
          StorageLive(_3);
          StorageLive(_4);
          StorageLive(_5);
          StorageLive(_6);
          StorageLive(_7);
          _9 = const main::promoted[0];
-         _7 = _9;
+         _7 = const {ALLOC1<imm>: &std::alloc::Global};
          StorageLive(_8);
-         _8 = _1;
-         _6 = std::alloc::Global::alloc_impl(move _7, move _8, const false) -> [return: bb4, unwind unreachable];
+         _8 = const Layout {{ size: Indirect { alloc_id: ALLOC0, offset: Size(4 bytes) }: usize, align: std::ptr::Alignment(Scalar(0x00000000): std::ptr::alignment::AlignmentEnum) }};
+         _6 = std::alloc::Global::alloc_impl(const {ALLOC1<imm>: &std::alloc::Global}, const Layout {{ size: Indirect { alloc_id: ALLOC0, offset: Size(4 bytes) }: usize, align: std::ptr::Alignment(Scalar(0x00000000): std::ptr::alignment::AlignmentEnum) }}, const false) -> [return: bb4, unwind unreachable];
      }
  
      bb4: {
          StorageDead(_8);
          StorageDead(_7);
          StorageLive(_12);
          StorageLive(_15);
          _12 = discriminant(_6);
          switchInt(move _12) -> [0: bb6, 1: bb5, otherwise: bb1];
      }
  
      bb5: {
          _15 = const "called `Result::unwrap()` on an `Err` value";
          StorageLive(_16);
          StorageLive(_17);
          _17 = &_13;
          _16 = move _17 as &dyn std::fmt::Debug (PointerCoercion(Unsize));
          StorageDead(_17);
          _14 = result::unwrap_failed(move _15, move _16) -> unwind unreachable;
      }
  
      bb6: {
          _5 = move ((_6 as Ok).0: std::ptr::NonNull<[u8]>);
          StorageDead(_15);
          StorageDead(_12);
          StorageDead(_6);
-         StorageLive(_18);
+         nop;
          _18 = (_5.0: *const [u8]);
-         _4 = move _18 as *mut [u8] (PtrToPtr);
-         StorageDead(_18);
+         _4 = _18 as *mut [u8] (PtrToPtr);
+         nop;
          StorageDead(_5);
-         _3 = move _4 as *mut u8 (PtrToPtr);
+         _3 = _18 as *mut u8 (PtrToPtr);
          StorageDead(_4);
          StorageDead(_3);
-         StorageDead(_1);
+         nop;
          return;
      }
  }
+ 
+ ALLOC0 (size: 8, align: 4) {
+     00 00 00 00 __ __ __ __                         │ ....░░░░
+ }
+ 
+ ALLOC1 (size: 0, align: 1) {}