ir: Add version of compute_trycatch for IRCode (JuliaLang#54035)

For ir transform passes that need to be aware of current_scope.
Currently no users in Base, but available for external absint.

---------

Co-authored-by: Shuhei Kadowaki <[email protected]>

base/compiler/inferencestate.jl

@@ -368,7 +368,21 @@ is_inferred(result::InferenceResult) = result.result !== nothing
 
 was_reached(sv::InferenceState, pc::Int) = sv.ssavaluetypes[pc] !== NOT_FOUND
 
-function compute_trycatch(code::Vector{Any}, ip::BitSet)
+compute_trycatch(ir::IRCode, ip::BitSet) = compute_trycatch(ir.stmts.stmt, ip, ir.cfg.blocks)
+
+"""
+ compute_trycatch(code, ip [, bbs]) -> (handler_at, handlers)
+
+Given the code of a function, compute, at every statement, the current
+try/catch handler, and the current exception stack top. This function returns
+a tuple of:
+
+ 1. `handler_at`: A statement length vector of tuples `(catch_handler, exception_stack)`,
+ which are indices into `handlers`
+
+ 2. `handlers`: A `TryCatchFrame` vector of handlers
+"""
+function compute_trycatch(code::Vector{Any}, ip::BitSet, bbs::Union{Vector{BasicBlock}, Nothing}=nothing)
  # The goal initially is to record the frame like this for the state at exit:
  # 1: (enter 3) # == 0
  # 3: (expr) # == 1
@@ -388,6 +402,7 @@ function compute_trycatch(code::Vector{Any}, ip::BitSet)
  stmt = code[pc]
  if isa(stmt, EnterNode)
  l = stmt.catch_dest
+ (bbs !== nothing) && (l = first(bbs[l].stmts))
  push!(handlers, TryCatchFrame(Bottom, isdefined(stmt, :scope) ? Bottom : nothing, pc))
  handler_id = length(handlers)
  handler_at[pc + 1] = (handler_id, 0)
@@ -412,8 +427,10 @@ function compute_trycatch(code::Vector{Any}, ip::BitSet)
  stmt = code[pc]
  if isa(stmt, GotoNode)
  pc´ = stmt.label
+ (bbs !== nothing) && (pc´ = first(bbs[pc´].stmts))
  elseif isa(stmt, GotoIfNot)
  l = stmt.dest::Int
+ (bbs !== nothing) && (l = first(bbs[l].stmts))
  if handler_at[l] != cur_stacks
  @assert handler_at[l][1] == 0 || handler_at[l][1] == cur_stacks[1] "unbalanced try/catch"
  handler_at[l] = cur_stacks
@@ -424,6 +441,7 @@ function compute_trycatch(code::Vector{Any}, ip::BitSet)
  break
  elseif isa(stmt, EnterNode)
  l = stmt.catch_dest
+ (bbs !== nothing) && (l = first(bbs[l].stmts))
  # We assigned a handler number above. Here we just merge that
  # with out current handler information.
  if l != 0