irinterp: Fix accidentally introduced deletion of effectful statement

I moved around some code in #49692 that broadened the replacement of
statements by their const results. This is fine for how we're currently
using irinterp in base, because we're requiring some fairly strong
effects, but some downstream pipelines (and potentially Base in the future)
want to use irinterp on code with arbitrary effects, so put in an
appropriate check.

Author: Keno

base/compiler/abstractinterpretation.jl

@@ -2544,6 +2544,7 @@ end
 function abstract_eval_statement(interp::AbstractInterpreter, @nospecialize(e), vtypes::VarTable, sv::InferenceState)
     if !isa(e, Expr)
         if isa(e, PhiNode)
+            add_curr_ssaflag!(sv, IR_FLAG_EFFECT_FREE)
             return abstract_eval_phi(interp, e, vtypes, sv)
         end
         return abstract_eval_special_value(interp, e, vtypes, sv)

base/compiler/ssair/irinterp.jl

@@ -128,16 +128,12 @@ function reprocess_instruction!(interp::AbstractInterpreter, idx::Int, bb::Union
         end
         return propagate_control_effects!(interp, idx, inst, irsv, extra_reprocess)
     end
-
     rt = nothing
     if isa(inst, Expr)
         head = inst.head
         if head === :call || head === :foreigncall || head === :new || head === :splatnew
             (; rt, effects) = abstract_eval_statement_expr(interp, inst, nothing, irsv)
             ir.stmts[idx][:flag] |= flags_for_effects(effects)
-            if is_foldable(effects) && isa(rt, Const) && is_inlineable_constant(rt.val)
-                ir.stmts[idx][:inst] = quoted(rt.val)
-            end
         elseif head === :invoke
             rt, nothrow = concrete_eval_invoke(interp, inst, inst.args[1]::MethodInstance, irsv)
             if nothrow
@@ -167,7 +163,7 @@ function reprocess_instruction!(interp::AbstractInterpreter, idx::Int, bb::Union
     if rt !== nothing
         if isa(rt, Const)
             ir.stmts[idx][:type] = rt
-            if is_inlineable_constant(rt.val)
+            if is_inlineable_constant(rt.val) && (ir.stmts[idx][:flag] & IR_FLAG_EFFECT_FREE) != 0
                 ir.stmts[idx][:inst] = quoted(rt.val)
             end
             return true