Squashed implementation of the pass

2 files changed, 77 insertions, 0 deletions

diff --git a/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff b/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
new file mode 100644
index 00000000000..d2056ac13a7
--- /dev/null
+++ b/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
@@ -0,0 +1,63 @@
+- // MIR for `bound` before LowerSliceLenCalls
++ // MIR for `bound` after LowerSliceLenCalls
+  
+  fn bound(_1: usize, _2: &[u8]) -> u8 {
+      debug index => _1;                   // in scope 0 at $DIR/lower_slice_len.rs:4:14: 4:19
+      debug slice => _2;                   // in scope 0 at $DIR/lower_slice_len.rs:4:28: 4:33
+      let mut _0: u8;                      // return place in scope 0 at $DIR/lower_slice_len.rs:4:45: 4:47
+      let mut _3: bool;                    // in scope 0 at $DIR/lower_slice_len.rs:5:8: 5:27
+      let mut _4: usize;                   // in scope 0 at $DIR/lower_slice_len.rs:5:8: 5:13
+      let mut _5: usize;                   // in scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
+      let mut _6: &[u8];                   // in scope 0 at $DIR/lower_slice_len.rs:5:16: 5:21
+      let _7: usize;                       // in scope 0 at $DIR/lower_slice_len.rs:6:15: 6:20
+      let mut _8: usize;                   // in scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
+      let mut _9: bool;                    // in scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
+  
+      bb0: {
+          StorageLive(_3);                 // scope 0 at $DIR/lower_slice_len.rs:5:8: 5:27
+          StorageLive(_4);                 // scope 0 at $DIR/lower_slice_len.rs:5:8: 5:13
+          _4 = _1;                         // scope 0 at $DIR/lower_slice_len.rs:5:8: 5:13
+          StorageLive(_5);                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
+          StorageLive(_6);                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:21
+          _6 = &(*_2);                     // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:21
+-         _5 = core::slice::<impl [u8]>::len(move _6) -> bb1; // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
+-                                          // mir::Constant
+-                                          // + span: $DIR/lower_slice_len.rs:5:22: 5:25
+-                                          // + literal: Const { ty: for<'r> fn(&'r [u8]) -> usize {core::slice::<impl [u8]>::len}, val: Value(Scalar(<ZST>)) }
++         _5 = Len((*_6));                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
++         goto -> bb1;                     // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
+      }
+  
+      bb1: {
+          StorageDead(_6);                 // scope 0 at $DIR/lower_slice_len.rs:5:26: 5:27
+          _3 = Lt(move _4, move _5);       // scope 0 at $DIR/lower_slice_len.rs:5:8: 5:27
+          StorageDead(_5);                 // scope 0 at $DIR/lower_slice_len.rs:5:26: 5:27
+          StorageDead(_4);                 // scope 0 at $DIR/lower_slice_len.rs:5:26: 5:27
+          switchInt(move _3) -> [false: bb3, otherwise: bb2]; // scope 0 at $DIR/lower_slice_len.rs:5:5: 9:6
+      }
+  
+      bb2: {
+          StorageLive(_7);                 // scope 0 at $DIR/lower_slice_len.rs:6:15: 6:20
+          _7 = _1;                         // scope 0 at $DIR/lower_slice_len.rs:6:15: 6:20
+          _8 = Len((*_2));                 // scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
+          _9 = Lt(_7, _8);                 // scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
+          assert(move _9, "index out of bounds: the length is {} but the index is {}", move _8, _7) -> bb4; // scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
+      }
+  
+      bb3: {
+          _0 = const 42_u8;                // scope 0 at $DIR/lower_slice_len.rs:8:9: 8:11
+          goto -> bb5;                     // scope 0 at $DIR/lower_slice_len.rs:5:5: 9:6
+      }
+  
+      bb4: {
+          _0 = (*_2)[_7];                  // scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
+          StorageDead(_7);                 // scope 0 at $DIR/lower_slice_len.rs:7:5: 7:6
+          goto -> bb5;                     // scope 0 at $DIR/lower_slice_len.rs:5:5: 9:6
+      }
+  
+      bb5: {
+          StorageDead(_3);                 // scope 0 at $DIR/lower_slice_len.rs:9:5: 9:6
+          return;                          // scope 0 at $DIR/lower_slice_len.rs:10:2: 10:2
+      }
+  }
+  
diff --git a/src/test/mir-opt/lower_slice_len.rs b/src/test/mir-opt/lower_slice_len.rs
new file mode 100644
index 00000000000..f2438e69749
--- /dev/null
+++ b/src/test/mir-opt/lower_slice_len.rs
@@ -0,0 +1,14 @@
+// compile-flags: -Z mir-opt-level=3
+
+// EMIT_MIR lower_slice_len.bound.LowerSliceLenCalls.diff
+pub fn bound(index: usize, slice: &[u8]) -> u8 {
+    if index < slice.len() {
+        slice[index]
+    } else {
+        42
+    }
+}
+
+fn main() {
+    let _ = bound(1, &[1, 2, 3]);
+}