Fix checker: after moving edge-moves to prior to last branch of block (for simpler semantics for library user), we can no longer check blockparams; but this is fine because they do not exist in post-regalloc code.

src/checker.rs

@@ -549,6 +549,11 @@ impl<'a, F: Function> Checker<'a, F> {
                     self.bb_insts.get_mut(&block).unwrap().push(checkinst);
                 }
 
+                // Skip if this is a branch: the blockparams do not
+                // exist in post-regalloc code, and the edge-moves
+                // have to be inserted before the branch rather than
+                // after.
+                if !self.f.is_branch(inst) {
                     // Instruction itself.
                     let operands: Vec<_> = self.f.inst_operands(inst).iter().cloned().collect();
                     let allocs: Vec<_> = out.inst_allocs(inst).iter().cloned().collect();
@@ -561,6 +566,7 @@ impl<'a, F: Function> Checker<'a, F> {
                     };
                     debug!("checker: adding inst {:?}", checkinst);
                     self.bb_insts.get_mut(&block).unwrap().push(checkinst);
+                }
 
                 // Any inserted edits after instruction.
                 self.handle_edits(block, out, &mut insert_idx, ProgPoint::after(inst));