JumpThreading: Add test for incorrect Not behaviour

tests/mir-opt/jump_threading.not_int.JumpThreading.panic-abort.diff

@@ -0,0 +1,46 @@
+- // MIR for `not_int` before JumpThreading
++ // MIR for `not_int` after JumpThreading
+
+  fn not_int() -> i32 {
+      let mut _0: i32;
+      let _1: i32;
+      let mut _2: bool;
+      let mut _3: i32;
+      let mut _4: i32;
+      scope 1 {
+          debug a => _1;
+      }
+
+      bb0: {
+          StorageLive(_1);
+          _1 = const 1_i32;
+          StorageLive(_2);
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = copy _1;
+          _3 = Not(move _4);
+          StorageDead(_4);
+          _2 = Eq(move _3, const 0_i32);
+-         switchInt(move _2) -> [0: bb2, otherwise: bb1];
++         goto -> bb1;
+      }
+
+      bb1: {
+          StorageDead(_3);
+          _0 = const 1_i32;
+          goto -> bb3;
+      }
+
+      bb2: {
+          StorageDead(_3);
+          _0 = const 0_i32;
+          goto -> bb3;
+      }
+
+      bb3: {
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+

tests/mir-opt/jump_threading.not_int.JumpThreading.panic-unwind.diff

@@ -0,0 +1,46 @@
+- // MIR for `not_int` before JumpThreading
++ // MIR for `not_int` after JumpThreading
+
+  fn not_int() -> i32 {
+      let mut _0: i32;
+      let _1: i32;
+      let mut _2: bool;
+      let mut _3: i32;
+      let mut _4: i32;
+      scope 1 {
+          debug a => _1;
+      }
+
+      bb0: {
+          StorageLive(_1);
+          _1 = const 1_i32;
+          StorageLive(_2);
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = copy _1;
+          _3 = Not(move _4);
+          StorageDead(_4);
+          _2 = Eq(move _3, const 0_i32);
+-         switchInt(move _2) -> [0: bb2, otherwise: bb1];
++         goto -> bb1;
+      }
+
+      bb1: {
+          StorageDead(_3);
+          _0 = const 1_i32;
+          goto -> bb3;
+      }
+
+      bb2: {
+          StorageDead(_3);
+          _0 = const 0_i32;
+          goto -> bb3;
+      }
+
+      bb3: {
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+

tests/mir-opt/jump_threading.rs

@@ -531,6 +531,15 @@ fn floats() -> u32 {
     if x == 0.0 { 0 } else { 1 }
 }
 
+fn not_int() -> i32 {
+    // CHECK-LABEL: fn not_int(
+
+    // Test for issue #131195, where !a == b is assumed to be equivalent to a != b
+    // This is only the case for bools
+    let a = 1;
+    if !a == 0 { 1 } else { 0 }
+}
+
 fn main() {
     // CHECK-LABEL: fn main(
     too_complex(Ok(0));
@@ -546,6 +555,7 @@ fn main() {
     aggregate(7);
     assume(7, false);
     floats();
+    not_int();
 }
 
 // EMIT_MIR jump_threading.too_complex.JumpThreading.diff
@@ -562,3 +572,4 @@ fn main() {
 // EMIT_MIR jump_threading.assume.JumpThreading.diff
 // EMIT_MIR jump_threading.aggregate_copy.JumpThreading.diff
 // EMIT_MIR jump_threading.floats.JumpThreading.diff
+// EMIT_MIR jump_threading.not_int.JumpThreading.diff