adjust to the :enter IR changes made in JuliaLang/julia#52300 (#599)

I don't expect this commit to fix the CI on 🔥, but since these
changes are straightforward, we should be able to go ahead and merge
this as is.

src/interpret.jl

@@ -370,7 +370,6 @@ function maybe_assign!(frame, @nospecialize(stmt), @nospecialize(val))
 end
 maybe_assign!(frame, @nospecialize(val)) = maybe_assign!(frame, pc_expr(frame), val)
 
-
 function eval_rhs(@nospecialize(recurse), frame, node::Expr)
     head = node.head
     if head === :new
@@ -399,6 +398,7 @@ function eval_rhs(@nospecialize(recurse), frame, node::Expr)
         val = (node.args[1]::QuoteNode).value
         return isa(val, Expr) ? copy(val) : val
     elseif head === :enter
+        # XXX This seems to be dead code
         return length(frame.framedata.exception_frames)
     elseif head === :boundscheck
         return true
@@ -565,6 +565,9 @@ function step_expr!(@nospecialize(recurse), frame, @nospecialize(node), istoplev
         elseif istoplevel && isa(node, LineNumberNode)
         elseif istoplevel && isa(node, Symbol)
             rhs = getfield(moduleof(frame), node)
+        elseif @static (isdefined(Core.IR, :EnterNode) && true) && isa(node, Core.IR.EnterNode)
+            rhs = node.catch_dest
+            push!(data.exception_frames, rhs)
         else
             rhs = @lookup(frame, node)
         end

src/optimize.jl

@@ -54,12 +54,10 @@ function renumber_ssa!(stmts::Vector{Any}, ssalookup)
             stmts[i] = SSAValue(ssalookup[stmt.id])
         elseif isa(stmt, NewSSAValue)
             stmts[i] = SSAValue(stmt.id)
+        elseif isexpr(stmt, :enter)
+            stmt.args[end] = jumplookup(ssalookup, stmt.args[1]::Int)
         elseif isa(stmt, Expr)
-            stmt = replace_ssa(stmt, ssalookup)
-            if stmt.head === :enter
-                stmt.args[end] = jumplookup(ssalookup, stmt.args[1]::Int)
-            end
-            stmts[i] = stmt
+            stmts[i] = replace_ssa(stmt, ssalookup)
         elseif isa(stmt, GotoIfNot)
             cond = stmt.cond
             if isa(cond, SSAValue)
@@ -71,6 +69,8 @@ function renumber_ssa!(stmts::Vector{Any}, ssalookup)
             if isa(val, SSAValue)
                 stmts[i] = ReturnNode(SSAValue(ssalookup[val.id]))
             end
+        elseif @static (isdefined(Core.IR, :EnterNode) && true) && isa(stmt, Core.IR.EnterNode)
+            stmts[i] = Core.IR.EnterNode(jumplookup(ssalookup, stmt.catch_dest))
         end
     end
     return stmts