Special case deref projections in SsaVisitor.

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/mir-opt/copy-prop/reborrow.rs b/tests/mir-opt/copy-prop/reborrow.rs
new file mode 100644
index 00000000000..a1624215feb
--- /dev/null
+++ b/tests/mir-opt/copy-prop/reborrow.rs
@@ -0,0 +1,39 @@
+// Check that CopyProp considers reborrows as not mutating the pointer.
+// unit-test: CopyProp
+
+#![feature(raw_ref_op)]
+
+// EMIT_MIR reborrow.remut.CopyProp.diff
+fn remut(mut x: u8) {
+    let a = &mut x;
+    let b = &mut *a; //< this cannot mutate a.
+    let c = a; //< so `c` and `a` can be merged.
+}
+
+// EMIT_MIR reborrow.reraw.CopyProp.diff
+fn reraw(mut x: u8) {
+    let a = &mut x;
+    let b = &raw mut *a; //< this cannot mutate a.
+    let c = a; //< so `c` and `a` can be merged.
+}
+
+// EMIT_MIR reborrow.miraw.CopyProp.diff
+fn miraw(mut x: u8) {
+    let a = &raw mut x;
+    let b = unsafe { &raw mut *a }; //< this cannot mutate a.
+    let c = a; //< so `c` and `a` can be merged.
+}
+
+// EMIT_MIR reborrow.demiraw.CopyProp.diff
+fn demiraw(mut x: u8) {
+    let a = &raw mut x;
+    let b = unsafe { &mut *a }; //< this cannot mutate a.
+    let c = a; //< so `c` and `a` can be merged.
+}
+
+fn main() {
+    remut(0);
+    reraw(0);
+    miraw(0);
+    demiraw(0);
+}