More GVN for PtrMetadata

`PtrMetadata` doesn't care about `*const`/`*mut`/`&`/`&mut`, so GVN away those casts in its argument.

This includes updating MIR to allow calling PtrMetadata on references too, not just raw pointers.  That means that `[T]::len` can be just `_0 = PtrMetadata(_1)`, for example.

# Conflicts:
#	tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-abort.mir
#	tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-unwind.mir

9 files changed, 218 insertions, 62 deletions

diff --git a/tests/mir-opt/gvn.array_len.GVN.panic-abort.diff b/tests/mir-opt/gvn.array_len.GVN.panic-abort.diff
new file mode 100644
index 00000000000..90654e05662
--- /dev/null
+++ b/tests/mir-opt/gvn.array_len.GVN.panic-abort.diff
@@ -0,0 +1,31 @@
+- // MIR for `array_len` before GVN
++ // MIR for `array_len` after GVN
+  
+  fn array_len(_1: &mut [i32; 42]) -> usize {
+      debug x => _1;
+      let mut _0: usize;
+      let _2: &[i32];
+      let mut _3: &[i32; 42];
+      let mut _4: *const [i32];
+      scope 1 {
+          debug x => _2;
+      }
+  
+      bb0: {
+-         StorageLive(_2);
++         nop;
+          StorageLive(_3);
+          _3 = &(*_1);
+          _2 = move _3 as &[i32] (PointerCoercion(Unsize));
+          StorageDead(_3);
+          StorageLive(_4);
+          _4 = &raw const (*_2);
+-         _0 = PtrMetadata(move _4);
++         _0 = const 42_usize;
+          StorageDead(_4);
+-         StorageDead(_2);
++         nop;
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/gvn.array_len.GVN.panic-unwind.diff b/tests/mir-opt/gvn.array_len.GVN.panic-unwind.diff
new file mode 100644
index 00000000000..90654e05662
--- /dev/null
+++ b/tests/mir-opt/gvn.array_len.GVN.panic-unwind.diff
@@ -0,0 +1,31 @@
+- // MIR for `array_len` before GVN
++ // MIR for `array_len` after GVN
+  
+  fn array_len(_1: &mut [i32; 42]) -> usize {
+      debug x => _1;
+      let mut _0: usize;
+      let _2: &[i32];
+      let mut _3: &[i32; 42];
+      let mut _4: *const [i32];
+      scope 1 {
+          debug x => _2;
+      }
+  
+      bb0: {
+-         StorageLive(_2);
++         nop;
+          StorageLive(_3);
+          _3 = &(*_1);
+          _2 = move _3 as &[i32] (PointerCoercion(Unsize));
+          StorageDead(_3);
+          StorageLive(_4);
+          _4 = &raw const (*_2);
+-         _0 = PtrMetadata(move _4);
++         _0 = const 42_usize;
+          StorageDead(_4);
+-         StorageDead(_2);
++         nop;
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/gvn.fn_pointers.GVN.panic-abort.diff b/tests/mir-opt/gvn.fn_pointers.GVN.panic-abort.diff
index 25d0e5ccf49..0c49e706c9e 100644
--- a/tests/mir-opt/gvn.fn_pointers.GVN.panic-abort.diff
+++ b/tests/mir-opt/gvn.fn_pointers.GVN.panic-abort.diff
@@ -8,10 +8,10 @@
       let mut _3: fn(u8) -> u8;
       let _5: ();
       let mut _6: fn(u8) -> u8;
-      let mut _9: {closure@$DIR/gvn.rs:612:19: 612:21};
+      let mut _9: {closure@$DIR/gvn.rs:614:19: 614:21};
       let _10: ();
       let mut _11: fn();
-      let mut _13: {closure@$DIR/gvn.rs:612:19: 612:21};
+      let mut _13: {closure@$DIR/gvn.rs:614:19: 614:21};
       let _14: ();
       let mut _15: fn();
       scope 1 {
@@ -19,7 +19,7 @@
           let _4: fn(u8) -> u8;
           scope 2 {
               debug g => _4;
-              let _7: {closure@$DIR/gvn.rs:612:19: 612:21};
+              let _7: {closure@$DIR/gvn.rs:614:19: 614:21};
               scope 3 {
                   debug closure => _7;
                   let _8: fn();
@@ -62,16 +62,16 @@
           StorageDead(_6);
           StorageDead(_5);
 -         StorageLive(_7);
--         _7 = {closure@$DIR/gvn.rs:612:19: 612:21};
+-         _7 = {closure@$DIR/gvn.rs:614:19: 614:21};
 -         StorageLive(_8);
 +         nop;
-+         _7 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21};
++         _7 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
 +         nop;
           StorageLive(_9);
 -         _9 = _7;
 -         _8 = move _9 as fn() (PointerCoercion(ClosureFnPointer(Safe)));
-+         _9 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21};
-+         _8 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
++         _9 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
++         _8 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
           StorageDead(_9);
           StorageLive(_10);
           StorageLive(_11);
@@ -88,8 +88,8 @@
           StorageLive(_13);
 -         _13 = _7;
 -         _12 = move _13 as fn() (PointerCoercion(ClosureFnPointer(Safe)));
-+         _13 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21};
-+         _12 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
++         _13 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
++         _12 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
           StorageDead(_13);
           StorageLive(_14);
           StorageLive(_15);
diff --git a/tests/mir-opt/gvn.fn_pointers.GVN.panic-unwind.diff b/tests/mir-opt/gvn.fn_pointers.GVN.panic-unwind.diff
index 3c5fd944d6b..e5f865b74b9 100644
--- a/tests/mir-opt/gvn.fn_pointers.GVN.panic-unwind.diff
+++ b/tests/mir-opt/gvn.fn_pointers.GVN.panic-unwind.diff
@@ -8,10 +8,10 @@
       let mut _3: fn(u8) -> u8;
       let _5: ();
       let mut _6: fn(u8) -> u8;
-      let mut _9: {closure@$DIR/gvn.rs:612:19: 612:21};
+      let mut _9: {closure@$DIR/gvn.rs:614:19: 614:21};
       let _10: ();
       let mut _11: fn();
-      let mut _13: {closure@$DIR/gvn.rs:612:19: 612:21};
+      let mut _13: {closure@$DIR/gvn.rs:614:19: 614:21};
       let _14: ();
       let mut _15: fn();
       scope 1 {
@@ -19,7 +19,7 @@
           let _4: fn(u8) -> u8;
           scope 2 {
               debug g => _4;
-              let _7: {closure@$DIR/gvn.rs:612:19: 612:21};
+              let _7: {closure@$DIR/gvn.rs:614:19: 614:21};
               scope 3 {
                   debug closure => _7;
                   let _8: fn();
@@ -62,16 +62,16 @@
           StorageDead(_6);
           StorageDead(_5);
 -         StorageLive(_7);
--         _7 = {closure@$DIR/gvn.rs:612:19: 612:21};
+-         _7 = {closure@$DIR/gvn.rs:614:19: 614:21};
 -         StorageLive(_8);
 +         nop;
-+         _7 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21};
++         _7 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
 +         nop;
           StorageLive(_9);
 -         _9 = _7;
 -         _8 = move _9 as fn() (PointerCoercion(ClosureFnPointer(Safe)));
-+         _9 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21};
-+         _8 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
++         _9 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
++         _8 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
           StorageDead(_9);
           StorageLive(_10);
           StorageLive(_11);
@@ -88,8 +88,8 @@
           StorageLive(_13);
 -         _13 = _7;
 -         _12 = move _13 as fn() (PointerCoercion(ClosureFnPointer(Safe)));
-+         _13 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21};
-+         _12 = const ZeroSized: {closure@$DIR/gvn.rs:612:19: 612:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
++         _13 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21};
++         _12 = const ZeroSized: {closure@$DIR/gvn.rs:614:19: 614:21} as fn() (PointerCoercion(ClosureFnPointer(Safe)));
           StorageDead(_13);
           StorageLive(_14);
           StorageLive(_15);
diff --git a/tests/mir-opt/gvn.manual_slice_mut_len.GVN.panic-abort.diff b/tests/mir-opt/gvn.manual_slice_mut_len.GVN.panic-abort.diff
new file mode 100644
index 00000000000..c877d8a3c0e
--- /dev/null
+++ b/tests/mir-opt/gvn.manual_slice_mut_len.GVN.panic-abort.diff
@@ -0,0 +1,41 @@
+- // MIR for `manual_slice_mut_len` before GVN
++ // MIR for `manual_slice_mut_len` after GVN
+  
+  fn manual_slice_mut_len(_1: &mut [i32]) -> usize {
+      debug x => _1;
+      let mut _0: usize;
+      let _2: *mut [i32];
+      let mut _4: *mut [i32];
+      let mut _5: *const [i32];
+      scope 1 {
+          debug x => _2;
+          let _3: *const [i32];
+          scope 2 {
+              debug x => _3;
+          }
+      }
+  
+      bb0: {
+-         StorageLive(_2);
++         nop;
+          _2 = &raw mut (*_1);
+-         StorageLive(_3);
++         nop;
+          StorageLive(_4);
+          _4 = _2;
+-         _3 = move _4 as *const [i32] (PtrToPtr);
++         _3 = _2 as *const [i32] (PtrToPtr);
+          StorageDead(_4);
+          StorageLive(_5);
+          _5 = _3;
+-         _0 = PtrMetadata(move _5);
++         _0 = PtrMetadata(_1);
+          StorageDead(_5);
+-         StorageDead(_3);
+-         StorageDead(_2);
++         nop;
++         nop;
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/gvn.manual_slice_mut_len.GVN.panic-unwind.diff b/tests/mir-opt/gvn.manual_slice_mut_len.GVN.panic-unwind.diff
new file mode 100644
index 00000000000..c877d8a3c0e
--- /dev/null
+++ b/tests/mir-opt/gvn.manual_slice_mut_len.GVN.panic-unwind.diff
@@ -0,0 +1,41 @@
+- // MIR for `manual_slice_mut_len` before GVN
++ // MIR for `manual_slice_mut_len` after GVN
+  
+  fn manual_slice_mut_len(_1: &mut [i32]) -> usize {
+      debug x => _1;
+      let mut _0: usize;
+      let _2: *mut [i32];
+      let mut _4: *mut [i32];
+      let mut _5: *const [i32];
+      scope 1 {
+          debug x => _2;
+          let _3: *const [i32];
+          scope 2 {
+              debug x => _3;
+          }
+      }
+  
+      bb0: {
+-         StorageLive(_2);
++         nop;
+          _2 = &raw mut (*_1);
+-         StorageLive(_3);
++         nop;
+          StorageLive(_4);
+          _4 = _2;
+-         _3 = move _4 as *const [i32] (PtrToPtr);
++         _3 = _2 as *const [i32] (PtrToPtr);
+          StorageDead(_4);
+          StorageLive(_5);
+          _5 = _3;
+-         _0 = PtrMetadata(move _5);
++         _0 = PtrMetadata(_1);
+          StorageDead(_5);
+-         StorageDead(_3);
+-         StorageDead(_2);
++         nop;
++         nop;
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/gvn.rs b/tests/mir-opt/gvn.rs
index 720018f112e..74f1849c42a 100644
--- a/tests/mir-opt/gvn.rs
+++ b/tests/mir-opt/gvn.rs
@@ -7,7 +7,9 @@
 #![feature(custom_mir)]
 #![feature(core_intrinsics)]
 #![feature(freeze)]
+#![allow(ambiguous_wide_pointer_comparisons)]
 #![allow(unconditional_panic)]
+#![allow(unused)]
 
 use std::intrinsics::mir::*;
 use std::marker::Freeze;
@@ -816,6 +818,22 @@ fn casts_before_aggregate_raw_ptr(x: *const u32) -> *const [u8] {
     std::intrinsics::aggregate_raw_ptr(x, 4)
 }
 
+fn manual_slice_mut_len(x: &mut [i32]) -> usize {
+    // CHECK-LABEL: fn manual_slice_mut_len
+    // CHECK: _0 = PtrMetadata(_1);
+    let x: *mut [i32] = x;
+    let x: *const [i32] = x;
+    std::intrinsics::ptr_metadata(x)
+}
+
+// `.len()` on arrays ends up being something like this
+fn array_len(x: &mut [i32; 42]) -> usize {
+    // CHECK-LABEL: fn array_len
+    // CHECK: _0 = const 42_usize;
+    let x: &[i32] = x;
+    std::intrinsics::ptr_metadata(x)
+}
+
 fn main() {
     subexpression_elimination(2, 4, 5);
     wrap_unwrap(5);
@@ -880,3 +898,5 @@ fn identity<T>(x: T) -> T {
 // EMIT_MIR gvn.meta_of_ref_to_slice.GVN.diff
 // EMIT_MIR gvn.slice_from_raw_parts_as_ptr.GVN.diff
 // EMIT_MIR gvn.casts_before_aggregate_raw_ptr.GVN.diff
+// EMIT_MIR gvn.manual_slice_mut_len.GVN.diff
+// EMIT_MIR gvn.array_len.GVN.diff
diff --git a/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-abort.mir
index 41cca811922..2f13cfa4dab 100644
--- a/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-abort.mir
@@ -8,25 +8,24 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
     let mut _4: usize;
     scope 1 (inlined core::slice::<impl [u32]>::get_unchecked_mut::<std::ops::Range<usize>>) {
         let mut _5: *mut [u32];
-        let mut _12: *mut [u32];
+        let mut _11: *mut [u32];
         scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut) {
-            let mut _7: usize;
-            let _8: ();
-            let _9: usize;
+            let mut _6: usize;
+            let _7: ();
+            let _8: usize;
             scope 3 {
                 scope 6 (inlined core::slice::index::get_offset_len_mut_noubcheck::<u32>) {
-                    let _11: *mut u32;
+                    let _10: *mut u32;
                     scope 7 {
                     }
                     scope 8 (inlined core::slice::index::get_mut_noubcheck::<u32>) {
-                        let _10: *mut u32;
+                        let _9: *mut u32;
                         scope 9 {
                         }
                     }
                 }
             }
             scope 4 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::len) {
-                let mut _6: *const [u32];
                 scope 5 (inlined std::ptr::metadata::<[u32]>) {
                 }
             }
@@ -38,28 +37,25 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
         _4 = move (_2.1: usize);
         StorageLive(_5);
         _5 = &raw mut (*_1);
-        StorageLive(_9);
-        StorageLive(_7);
+        StorageLive(_8);
         StorageLive(_6);
-        _6 = _5 as *const [u32] (PtrToPtr);
-        _7 = PtrMetadata(_6);
-        StorageDead(_6);
-        _8 = <std::ops::Range<usize> as SliceIndex<[T]>>::get_unchecked_mut::precondition_check(_3, _4, move _7) -> [return: bb1, unwind unreachable];
+        _6 = PtrMetadata(_1);
+        _7 = <std::ops::Range<usize> as SliceIndex<[T]>>::get_unchecked_mut::precondition_check(_3, _4, move _6) -> [return: bb1, unwind unreachable];
     }
 
     bb1: {
-        StorageDead(_7);
-        _9 = SubUnchecked(_4, _3);
-        StorageLive(_11);
+        StorageDead(_6);
+        _8 = SubUnchecked(_4, _3);
         StorageLive(_10);
-        _10 = _5 as *mut u32 (PtrToPtr);
-        _11 = Offset(_10, _3);
-        StorageDead(_10);
-        _12 = *mut [u32] from (_11, _9);
-        StorageDead(_11);
+        StorageLive(_9);
+        _9 = _5 as *mut u32 (PtrToPtr);
+        _10 = Offset(_9, _3);
         StorageDead(_9);
+        _11 = *mut [u32] from (_10, _8);
+        StorageDead(_10);
+        StorageDead(_8);
         StorageDead(_5);
-        _0 = &mut (*_12);
+        _0 = &mut (*_11);
         return;
     }
 }
diff --git a/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-unwind.mir
index 41cca811922..2f13cfa4dab 100644
--- a/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-unwind.mir
@@ -8,25 +8,24 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
     let mut _4: usize;
     scope 1 (inlined core::slice::<impl [u32]>::get_unchecked_mut::<std::ops::Range<usize>>) {
         let mut _5: *mut [u32];
-        let mut _12: *mut [u32];
+        let mut _11: *mut [u32];
         scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut) {
-            let mut _7: usize;
-            let _8: ();
-            let _9: usize;
+            let mut _6: usize;
+            let _7: ();
+            let _8: usize;
             scope 3 {
                 scope 6 (inlined core::slice::index::get_offset_len_mut_noubcheck::<u32>) {
-                    let _11: *mut u32;
+                    let _10: *mut u32;
                     scope 7 {
                     }
                     scope 8 (inlined core::slice::index::get_mut_noubcheck::<u32>) {
-                        let _10: *mut u32;
+                        let _9: *mut u32;
                         scope 9 {
                         }
                     }
                 }
             }
             scope 4 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::len) {
-                let mut _6: *const [u32];
                 scope 5 (inlined std::ptr::metadata::<[u32]>) {
                 }
             }
@@ -38,28 +37,25 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
         _4 = move (_2.1: usize);
         StorageLive(_5);
         _5 = &raw mut (*_1);
-        StorageLive(_9);
-        StorageLive(_7);
+        StorageLive(_8);
         StorageLive(_6);
-        _6 = _5 as *const [u32] (PtrToPtr);
-        _7 = PtrMetadata(_6);
-        StorageDead(_6);
-        _8 = <std::ops::Range<usize> as SliceIndex<[T]>>::get_unchecked_mut::precondition_check(_3, _4, move _7) -> [return: bb1, unwind unreachable];
+        _6 = PtrMetadata(_1);
+        _7 = <std::ops::Range<usize> as SliceIndex<[T]>>::get_unchecked_mut::precondition_check(_3, _4, move _6) -> [return: bb1, unwind unreachable];
     }
 
     bb1: {
-        StorageDead(_7);
-        _9 = SubUnchecked(_4, _3);
-        StorageLive(_11);
+        StorageDead(_6);
+        _8 = SubUnchecked(_4, _3);
         StorageLive(_10);
-        _10 = _5 as *mut u32 (PtrToPtr);
-        _11 = Offset(_10, _3);
-        StorageDead(_10);
-        _12 = *mut [u32] from (_11, _9);
-        StorageDead(_11);
+        StorageLive(_9);
+        _9 = _5 as *mut u32 (PtrToPtr);
+        _10 = Offset(_9, _3);
         StorageDead(_9);
+        _11 = *mut [u32] from (_10, _8);
+        StorageDead(_10);
+        StorageDead(_8);
         StorageDead(_5);
-        _0 = &mut (*_12);
+        _0 = &mut (*_11);
         return;
     }
 }