Make :enter a proper node type

This is a prepratory commit in anticipation of giving :enter additional
responsibilities of entering and restoring dynamic scopes for ScopedValue
(c.f. #51352). This commit simply turns `:enter` into its own node type
(like the other terminators). The changes are largely mechanical from
the `Expr` version, but will make it easier to add additional semantics
in a follow up PR.

Author: Keno

base/boot.jl

@@ -459,6 +459,7 @@ eval(Core, quote
     ReturnNode(@nospecialize val) = $(Expr(:new, :ReturnNode, :val))
     ReturnNode() = $(Expr(:new, :ReturnNode)) # unassigned val indicates unreachable
     GotoIfNot(@nospecialize(cond), dest::Int) = $(Expr(:new, :GotoIfNot, :cond, :dest))
+    EnterNode(dest::Int) = $(Expr(:new, :EnterNode, :dest))
     LineNumberNode(l::Int) = $(Expr(:new, :LineNumberNode, :l, nothing))
     function LineNumberNode(l::Int, @nospecialize(f))
         isa(f, String) && (f = Symbol(f))
@@ -626,12 +627,12 @@ module IR
 export CodeInfo, MethodInstance, CodeInstance, GotoNode, GotoIfNot, ReturnNode,
     NewvarNode, SSAValue, SlotNumber, Argument,
     PiNode, PhiNode, PhiCNode, UpsilonNode, LineInfoNode,
-    Const, PartialStruct, InterConditional
+    Const, PartialStruct, InterConditional, EnterNode
 
 using Core: CodeInfo, MethodInstance, CodeInstance, GotoNode, GotoIfNot, ReturnNode,
     NewvarNode, SSAValue, SlotNumber, Argument,
     PiNode, PhiNode, PhiCNode, UpsilonNode, LineInfoNode,
-    Const, PartialStruct, InterConditional
+    Const, PartialStruct, InterConditional, EnterNode
 
 end # module IR
 
@@ -965,4 +966,7 @@ arraysize(a::Array) = a.size
 arraysize(a::Array, i::Int) = sle_int(i, nfields(a.size)) ? getfield(a.size, i) : 1
 export arrayref, arrayset, arraysize, const_arrayref
 
+# For convenience
+EnterNode(old::EnterNode, new_dest::Int) = EnterNode(new_dest)
+
 ccall(:jl_set_istopmod, Cvoid, (Any, Bool), Core, true)

base/compiler/abstractinterpretation.jl

@@ -3102,8 +3102,8 @@ function update_exc_bestguess!(@nospecialize(exct), frame::InferenceState, 𝕃
         handler_frame = frame.handlers[cur_hand]
         if !⊑(𝕃ₚ, exct, handler_frame.exct)
             handler_frame.exct = tmerge(𝕃ₚ, handler_frame.exct, exct)
-            enter = frame.src.code[handler_frame.enter_idx]::Expr
-            exceptbb = block_for_inst(frame.cfg, enter.args[1]::Int)
+            enter = frame.src.code[handler_frame.enter_idx]::EnterNode
+            exceptbb = block_for_inst(frame.cfg, enter.catch_dest)
             push!(frame.ip, exceptbb)
         end
     end
@@ -3114,8 +3114,8 @@ function propagate_to_error_handler!(currstate::VarTable, frame::InferenceState,
     # exception handler, BEFORE applying any state changes.
     cur_hand = frame.handler_at[frame.currpc][1]
     if cur_hand != 0
-        enter = frame.src.code[frame.handlers[cur_hand].enter_idx]::Expr
-        exceptbb = block_for_inst(frame.cfg, enter.args[1]::Int)
+        enter = frame.src.code[frame.handlers[cur_hand].enter_idx]::EnterNode
+        exceptbb = block_for_inst(frame.cfg, enter.catch_dest)
         if update_bbstate!(𝕃ᵢ, frame, exceptbb, currstate)
             push!(frame.ip, exceptbb)
         end
@@ -3256,8 +3256,9 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
                     end
                     ssavaluetypes[frame.currpc] = Any
                     @goto find_next_bb
-                elseif isexpr(stmt, :enter)
+                elseif isa(stmt, EnterNode)
                     ssavaluetypes[currpc] = Any
+                    add_curr_ssaflag!(frame, IR_FLAG_NOTHROW)
                     @goto fallthrough
                 elseif isexpr(stmt, :leave)
                     ssavaluetypes[currpc] = Any

base/compiler/inferencestate.jl

@@ -362,8 +362,8 @@ function compute_trycatch(code::Vector{Any}, ip::BitSet)
     # start from all :enter statements and record the location of the try
     for pc = 1:n
         stmt = code[pc]
-        if isexpr(stmt, :enter)
-            l = stmt.args[1]::Int
+        if isa(stmt, EnterNode)
+            l = stmt.catch_dest
             push!(handlers, TryCatchFrame(Bottom, pc))
             handler_id = length(handlers)
             handler_at[pc + 1] = (handler_id, 0)
@@ -396,15 +396,15 @@ function compute_trycatch(code::Vector{Any}, ip::BitSet)
             elseif isa(stmt, ReturnNode)
                 @assert !isdefined(stmt, :val) || cur_stacks[1] == 0 "unbalanced try/catch"
                 break
+            elseif isa(stmt, EnterNode)
+                l = stmt.catch_dest
+                # We assigned a handler number above. Here we just merge that
+                # with out current handler information.
+                handler_at[l] = (cur_stacks[1], handler_at[l][2])
+                cur_stacks = (handler_at[pc´][1], cur_stacks[2])
             elseif isa(stmt, Expr)
                 head = stmt.head
-                if head === :enter
-                    l = stmt.args[1]::Int
-                    # We assigned a handler number above. Here we just merge that
-                    # with out current handler information.
-                    handler_at[l] = (cur_stacks[1], handler_at[l][2])
-                    cur_stacks = (handler_at[pc´][1], cur_stacks[2])
-                elseif head === :leave
+                if head === :leave
                     l = 0
                     for j = 1:length(stmt.args)
                         arg = stmt.args[j]
@@ -415,7 +415,7 @@ function compute_trycatch(code::Vector{Any}, ip::BitSet)
                             if enter_stmt === nothing
                                 continue
                             end
-                            @assert isexpr(enter_stmt, :enter) "malformed :leave"
+                            @assert isa(enter_stmt, EnterNode) "malformed :leave"
                         end
                         l += 1
                     end

base/compiler/optimize.jl

@@ -270,6 +270,7 @@ function stmt_effect_flags(𝕃ₒ::AbstractLattice, @nospecialize(stmt), @nospe
     isa(stmt, PiNode) && return (true, true, true)
     isa(stmt, PhiNode) && return (true, true, true)
     isa(stmt, ReturnNode) && return (true, false, true)
+    isa(stmt, EnterNode) && return (true, false, true)
     isa(stmt, GotoNode) && return (true, false, true)
     isa(stmt, GotoIfNot) && return (true, false, ⊑(𝕃ₒ, argextype(stmt.cond, src), Bool))
     if isa(stmt, GlobalRef)
@@ -761,7 +762,7 @@ end
 function ((; sv)::ScanStmt)(inst::Instruction, lstmt::Int, bb::Int)
     stmt = inst[:stmt]
 
-    if isexpr(stmt, :enter)
+    if isa(stmt, EnterNode)
         # try/catch not yet modeled
         give_up_refinements!(sv)
         return nothing
@@ -971,8 +972,8 @@ function convert_to_ircode(ci::CodeInfo, sv::OptimizationState)
                     expr = nothing
                 end
                 code[i] = expr
-            elseif isexpr(expr, :enter)
-                catchdest = expr.args[1]::Int
+            elseif isa(expr, EnterNode)
+                catchdest = expr.catch_dest
                 if catchdest in sv.unreachable
                     cfg_delete_edge!(sv.cfg, block_for_inst(sv.cfg, i), block_for_inst(sv.cfg, catchdest))
                     code[i] = nothing
@@ -1239,12 +1240,6 @@ function statement_cost(ex::Expr, line::Int, src::Union{CodeInfo, IRCode}, sptyp
         return cost
     elseif head === :copyast
         return 100
-    elseif head === :enter
-        # try/catch is a couple function calls,
-        # but don't inline functions with try/catch
-        # since these aren't usually performance-sensitive functions,
-        # and llvm is more likely to miscompile them when these functions get large
-        return typemax(Int)
     end
     return 0
 end
@@ -1263,6 +1258,12 @@ function statement_or_branch_cost(@nospecialize(stmt), line::Int, src::Union{Cod
         thiscost = dst(stmt.label) < line ? 40 : 0
     elseif stmt isa GotoIfNot
         thiscost = dst(stmt.dest) < line ? 40 : 0
+    elseif stmt isa EnterNode
+        # try/catch is a couple function calls,
+        # but don't inline functions with try/catch
+        # since these aren't usually performance-sensitive functions,
+        # and llvm is more likely to miscompile them when these functions get large
+        thiscost = typemax(Int)
     end
     return thiscost
 end
@@ -1359,19 +1360,19 @@ function renumber_ir_elements!(body::Vector{Any}, ssachangemap::Vector{Int}, lab
                     i += 1
                 end
             end
+        elseif isa(el, EnterNode)
+            tgt = el.catch_dest
+            was_deleted = labelchangemap[tgt] == typemin(Int)
+            if was_deleted
+                body[i] = nothing
+            else
+                body[i] = EnterNode(el, tgt + labelchangemap[tgt])
+            end
         elseif isa(el, Expr)
             if el.head === :(=) && el.args[2] isa Expr
                 el = el.args[2]::Expr
             end
-            if el.head === :enter
-                tgt = el.args[1]::Int
-                was_deleted = labelchangemap[tgt] == typemin(Int)
-                if was_deleted
-                    body[i] = nothing
-                else
-                    el.args[1] = tgt + labelchangemap[tgt]
-                end
-            elseif !is_meta_expr_head(el.head)
+            if !is_meta_expr_head(el.head)
                 args = el.args
                 for i = 1:length(args)
                     el = args[i]

base/compiler/ssair/EscapeAnalysis/EscapeAnalysis.jl

@@ -652,7 +652,7 @@ function analyze_escapes(ir::IRCode, nargs::Int, 𝕃ₒ::AbstractLattice, get_e
                 elseif is_meta_expr_head(head)
                     # meta expressions doesn't account for any usages
                     continue
-                elseif head === :enter || head === :leave || head === :the_exception || head === :pop_exception
+                elseif head === :leave || head === :the_exception || head === :pop_exception
                     # ignore these expressions since escapes via exceptions are handled by `escape_exception!`
                     # `escape_exception!` conservatively propagates `AllEscape` anyway,
                     # and so escape information imposed on `:the_exception` isn't computed
@@ -666,6 +666,9 @@ function analyze_escapes(ir::IRCode, nargs::Int, 𝕃ₒ::AbstractLattice, get_e
                 else
                     add_conservative_changes!(astate, pc, stmt.args)
                 end
+            elseif isa(stmt, EnterNode)
+                # Handled via escape_exception!
+                continue
             elseif isa(stmt, ReturnNode)
                 if isdefined(stmt, :val)
                     add_escape_change!(astate, stmt.val, ReturnEscape(pc))
@@ -728,10 +731,10 @@ function compute_frameinfo(ir::IRCode)
     for idx in 1:nstmts+nnewnodes
         inst = ir[SSAValue(idx)]
         stmt = inst[:stmt]
-        if isexpr(stmt, :enter)
+        if isa(stmt, EnterNode)
             @assert idx ≤ nstmts "try/catch inside new_nodes unsupported"
             tryregions === nothing && (tryregions = UnitRange{Int}[])
-            leave_block = stmt.args[1]::Int
+            leave_block = stmt.catch_dest
             leave_pc = first(ir.cfg.blocks[leave_block].stmts)
             push!(tryregions, idx:leave_pc)
         elseif arrayinfo !== nothing

base/compiler/ssair/inlining.jl

@@ -459,8 +459,8 @@ function ir_inline_item!(compact::IncrementalCompact, idx::Int, argexprs::Vector
                 end
             elseif isa(stmt′, GotoNode)
                 stmt′ = GotoNode(stmt′.label + bb_offset)
-            elseif isa(stmt′, Expr) && stmt′.head === :enter
-                stmt′ = Expr(:enter, stmt′.args[1]::Int + bb_offset)
+            elseif isa(stmt′, EnterNode)
+                stmt′ = EnterNode(stmt′, stmt′.catch_dest + bb_offset)
             elseif isa(stmt′, GotoIfNot)
                 stmt′ = GotoIfNot(stmt′.cond, stmt′.dest + bb_offset)
             elseif isa(stmt′, PhiNode)
@@ -710,8 +710,8 @@ function batch_inline!(ir::IRCode, todo::Vector{Pair{Int,Any}}, propagate_inboun
                 end
             elseif isa(stmt, GotoNode)
                 compact[idx] = GotoNode(state.bb_rename[stmt.label])
-            elseif isa(stmt, Expr) && stmt.head === :enter
-                compact[idx] = Expr(:enter, state.bb_rename[stmt.args[1]::Int])
+            elseif isa(stmt, EnterNode)
+                compact[idx] = EnterNode(stmt, state.bb_rename[stmt.catch_dest])
             elseif isa(stmt, GotoIfNot)
                 compact[idx] = GotoIfNot(stmt.cond, state.bb_rename[stmt.dest])
             elseif isa(stmt, PhiNode)

base/compiler/ssair/ir.jl

@@ -2,7 +2,7 @@
 
 Core.PhiNode() = Core.PhiNode(Int32[], Any[])
 
-isterminator(@nospecialize(stmt)) = isa(stmt, GotoNode) || isa(stmt, GotoIfNot) || isa(stmt, ReturnNode)
+isterminator(@nospecialize(stmt)) = isa(stmt, GotoNode) || isa(stmt, GotoIfNot) || isa(stmt, ReturnNode) || isa(stmt, EnterNode)
 
 struct CFG
     blocks::Vector{BasicBlock}
@@ -60,16 +60,16 @@ block_for_inst(cfg::CFG, inst::Int) = block_for_inst(cfg.index, inst)
             # This is a fake dest to force the next stmt to start a bb
             idx < length(stmts) && push!(jump_dests, idx+1)
             push!(jump_dests, stmt.label)
+        elseif isa(stmt, EnterNode)
+            # :enter starts/ends a BB
+            push!(jump_dests, idx)
+            push!(jump_dests, idx+1)
+            # The catch block is a jump dest
+            push!(jump_dests, stmt.catch_dest)
         elseif isa(stmt, Expr)
             if stmt.head === :leave
                 # :leave terminates a BB
                 push!(jump_dests, idx+1)
-            elseif stmt.head === :enter
-                # :enter starts/ends a BB
-                push!(jump_dests, idx)
-                push!(jump_dests, idx+1)
-                # The catch block is a jump dest
-                push!(jump_dests, stmt.args[1]::Int)
             end
         end
         if isa(stmt, PhiNode)
@@ -125,11 +125,11 @@ function compute_basic_blocks(stmts::Vector{Any})
                 push!(blocks[block′].preds, num)
                 push!(b.succs, block′)
             end
-        elseif isexpr(terminator, :enter)
+        elseif isa(terminator, EnterNode)
             # :enter gets a virtual edge to the exception handler and
             # the exception handler gets a virtual edge from outside
             # the function.
-            block′ = block_for_inst(basic_block_index, terminator.args[1]::Int)
+            block′ = block_for_inst(basic_block_index, terminator.catch_dest)
             push!(blocks[block′].preds, num)
             push!(blocks[block′].preds, 0)
             push!(b.succs, block′)
@@ -456,6 +456,10 @@ struct UndefToken end; const UNDEF_TOKEN = UndefToken()
         isdefined(stmt, :val) || return OOB_TOKEN
         op == 1 || return OOB_TOKEN
         return stmt.val
+    elseif isa(stmt, EnterNode)
+        isdefined(stmt, :scope) || return OOB_TOKEN
+        op == 1 || return OOB_TOKEN
+        return stmt.scope
     elseif isa(stmt, PiNode)
         isdefined(stmt, :val) || return OOB_TOKEN
         op == 1 || return OOB_TOKEN
@@ -510,6 +514,9 @@ end
     elseif isa(stmt, GotoIfNot)
         op == 1 || throw(BoundsError())
         stmt = GotoIfNot(v, stmt.dest)
+    elseif isa(stmt, EnterNode)
+        op == 1 || throw(BoundsError())
+        stmt = EnterNode(stmt.catch_dest, v)
     elseif isa(stmt, ReturnNode)
         op == 1 || throw(BoundsError())
         stmt = typeof(stmt)(v)
@@ -544,7 +551,7 @@ end
 function userefs(@nospecialize(x))
     relevant = (isa(x, Expr) && is_relevant_expr(x)) ||
         isa(x, GotoIfNot) || isa(x, ReturnNode) || isa(x, SSAValue) || isa(x, NewSSAValue) ||
-        isa(x, PiNode) || isa(x, PhiNode) || isa(x, PhiCNode) || isa(x, UpsilonNode)
+        isa(x, PiNode) || isa(x, PhiNode) || isa(x, PhiCNode) || isa(x, UpsilonNode) || isa(x, EnterNode)
     return UseRefIterator(x, relevant)
 end
 
@@ -1379,13 +1386,15 @@ function process_node!(compact::IncrementalCompact, result_idx::Int, inst::Instr
             result[result_idx][:stmt] = GotoIfNot(cond, label)
             result_idx += 1
         end
+    elseif cfg_transforms_enabled && isa(stmt, EnterNode)
+        label = bb_rename_succ[stmt.catch_dest]
+        @assert label > 0
+        ssa_rename[idx] = SSAValue(result_idx)
+        result[result_idx][:stmt] = EnterNode(stmt, label)
+        result_idx += 1
     elseif isa(stmt, Expr)
         stmt = renumber_ssa2!(stmt, ssa_rename, used_ssas, new_new_used_ssas, late_fixup, result_idx, do_rename_ssa, mark_refined!)::Expr
-        if cfg_transforms_enabled && isexpr(stmt, :enter)
-            label = bb_rename_succ[stmt.args[1]::Int]
-            @assert label > 0
-            stmt.args[1] = label
-        elseif isexpr(stmt, :throw_undef_if_not)
+        if isexpr(stmt, :throw_undef_if_not)
             cond = stmt.args[2]
             if isa(cond, Bool) && cond === true
                 # cond was folded to true - this statement
@@ -1445,7 +1454,7 @@ function process_node!(compact::IncrementalCompact, result_idx::Int, inst::Instr
         ssa_rename[idx] = SSAValue(result_idx)
         result[result_idx][:stmt] = stmt
         result_idx += 1
-    elseif isa(stmt, ReturnNode) || isa(stmt, UpsilonNode) || isa(stmt, GotoIfNot)
+    elseif isa(stmt, ReturnNode) || isa(stmt, UpsilonNode) || isa(stmt, GotoIfNot) || isa(stmt, EnterNode)
         ssa_rename[idx] = SSAValue(result_idx)
         result[result_idx][:stmt] = renumber_ssa2!(stmt, ssa_rename, used_ssas, new_new_used_ssas, late_fixup, result_idx, do_rename_ssa, mark_refined!)
         result_idx += 1

base/compiler/ssair/irinterp.jl

@@ -96,7 +96,7 @@ function kill_terminator_edges!(irsv::IRInterpretationState, term_idx::Int, bb::
     elseif isa(stmt, ReturnNode)
         # Nothing to do
     else
-        @assert !isexpr(stmt, :enter)
+        @assert !isa(stmt, EnterNode)
         kill_edge!(irsv, bb, bb+1)
     end
 end
@@ -222,8 +222,8 @@ function process_terminator!(@nospecialize(stmt), bb::Int, bb_ip::BitSetBoundedM
         backedge || push!(bb_ip, stmt.dest)
         push!(bb_ip, bb+1)
         return backedge
-    elseif isexpr(stmt, :enter)
-        dest = stmt.args[1]::Int
+    elseif isa(stmt, EnterNode)
+        dest = stmt.catch_dest
         @assert dest > bb
         push!(bb_ip, dest)
         push!(bb_ip, bb+1)
@@ -329,8 +329,7 @@ function _ir_abstract_constant_propagation(interp::AbstractInterpreter, irsv::IR
             delete!(ssa_refined, idx)
         end
         check_ret!(stmt, idx)
-        is_terminator_or_phi = (isa(stmt, PhiNode) || isa(stmt, GotoNode) ||
-            isa(stmt, GotoIfNot) || isa(stmt, ReturnNode) || isexpr(stmt, :enter))
+        is_terminator_or_phi = (isa(stmt, PhiNode) || isterminator(stmt))
         if typ === Bottom && !(idx == lstmt && is_terminator_or_phi)
             return true
         end