Add codegen test for branchy bool match

Author: clubby789

Diff for: tests/codegen/issues/issue-108395-branchy-bool-match.rs

@@ -0,0 +1,27 @@
+//@ compile-flags: -O -Zmerge-functions=disabled
+//! Test for <https://github.com/rust-lang/rust/issues/108395>. Check that
+//! matching on two bools with wildcards does not produce branches.
+#![crate_type = "lib"]
+
+// CHECK-LABEL: @wildcard(
+#[no_mangle]
+pub fn wildcard(a: u16, b: u16, v: u16) -> u16 {
+    // CHECK-NOT: br
+    match (a == v, b == v) {
+        (true, false) => 0,
+        (false, true) => u16::MAX,
+        _ => 1 << 15, // half
+    }
+}
+
+// CHECK-LABEL: @exhaustive(
+#[no_mangle]
+pub fn exhaustive(a: u16, b: u16, v: u16) -> u16 {
+    // CHECK-NOT: br
+    match (a == v, b == v) {
+        (true, false) => 0,
+        (false, true) => u16::MAX,
+        (true, true) => 1 << 15,
+        (false, false) => 1 << 15,
+    }
+}