optimizer: handle GlobalRef based on assume_bindings_static

Following up #53750.
External abstract interpreters with `assume_bindings_static` enabled
assume nothrow-ness of defined `GlobalRef`s no matter if they are
constant during abstract interpretation. However, post-#53750, the
optimizer’s verification switched to stricter checks, causing errors
in such interpreters. This commit makes `IRCode` hold
`assume_bindings_static::Bool` info to ensure that inlining and
verification behaviors are synced with abstract interpretation.

base/compiler/abstractinterpretation.jl

@@ -2842,7 +2842,7 @@ function abstract_eval_globalref(interp::AbstractInterpreter, g::GlobalRef, sv::
     rt = abstract_eval_globalref_type(g)
     consistent = inaccessiblememonly = ALWAYS_FALSE
     nothrow = false
-    if isa(rt, Const)
+    if isa(rt, Const) # implies `isdefinedconst_globalref(g) === true`
         consistent = ALWAYS_TRUE
         nothrow = true
         if is_mutation_free_argtype(rt)
@@ -2855,8 +2855,6 @@ function abstract_eval_globalref(interp::AbstractInterpreter, g::GlobalRef, sv::
         else
             rt = Union{}
         end
-    elseif isdefinedconst_globalref(g)
-        nothrow = true
     end
     return RTEffects(rt, nothrow ? Union{} : UndefVarError, Effects(EFFECTS_TOTAL; consistent, nothrow, inaccessiblememonly))
 end

base/compiler/optimize.jl

@@ -286,6 +286,9 @@ function new_expr_effect_flags(𝕃ₒ::AbstractLattice, args::Vector{Any}, src:
     return (false, true, true)
 end
 
+assume_bindings_static(ir::IRCode) = ir.assume_bindings_static
+assume_bindings_static(compact::IncrementalCompact) = assume_bindings_static(compact.ir)
+
 """
     stmt_effect_flags(stmt, rt, src::Union{IRCode,IncrementalCompact}) ->
         (consistent::Bool, removable::Bool, nothrow::Bool)
@@ -301,7 +304,12 @@ function stmt_effect_flags(𝕃ₒ::AbstractLattice, @nospecialize(stmt), @nospe
     isa(stmt, GotoNode) && return (true, false, true)
     isa(stmt, GotoIfNot) && return (true, false, ⊑(𝕃ₒ, argextype(stmt.cond, src), Bool))
     if isa(stmt, GlobalRef)
-        nothrow = consistent = isdefinedconst_globalref(stmt)
+        if assume_bindings_static(src)
+            nothrow = isdefined_globalref(stmt)
+            consistent = nothrow & isconst(stmt)
+        else
+            nothrow = consistent = isdefinedconst_globalref(stmt)
+        end
         return (consistent, nothrow, nothrow)
     elseif isa(stmt, Expr)
         (; head, args) = stmt
@@ -1131,7 +1139,6 @@ function convert_to_ircode(ci::CodeInfo, sv::OptimizationState)
     # Go through and add an unreachable node after every
     # Union{} call. Then reindex labels.
     stmtinfo = sv.stmt_info
-    meta = Expr[]
     idx = 1
     oldidx = 1
     nstmts = length(code)
@@ -1231,9 +1238,7 @@ function convert_to_ircode(ci::CodeInfo, sv::OptimizationState)
         renumber_cfg_stmts!(sv.cfg, blockchangemap)
     end
 
-    for i = 1:length(code)
-        code[i] = process_meta!(meta, code[i])
-    end
+    meta = process_meta!(code)
     strip_trailing_junk!(code, ssavaluetypes, ssaflags, di, sv.cfg, stmtinfo)
     types = Any[]
     stmts = InstructionStream(code, types, stmtinfo, codelocs, ssaflags)
@@ -1244,12 +1249,16 @@ function convert_to_ircode(ci::CodeInfo, sv::OptimizationState)
     return IRCode(stmts, sv.cfg, di, argtypes, meta, sv.sptypes)
 end
 
-function process_meta!(meta::Vector{Expr}, @nospecialize stmt)
-    if isexpr(stmt, :meta) && length(stmt.args) ≥ 1
-        push!(meta, stmt)
-        return nothing
+function process_meta!(code::Vector{Any})
+    meta = Expr[]
+    for i = 1:length(code)
+        stmt = code[i]
+        if isexpr(stmt, :meta) && length(stmt.args) ≥ 1
+            push!(meta, stmt)
+            code[i] = nothing
+        end
     end
-    return stmt
+    return meta
 end
 
 function slot2reg(ir::IRCode, ci::CodeInfo, sv::OptimizationState)

base/compiler/ssair/ir.jl

@@ -428,22 +428,26 @@ struct IRCode
     cfg::CFG
     new_nodes::NewNodeStream
     meta::Vector{Expr}
+    assume_bindings_static::Bool # XXX propagate `interp::AbstractInterpreter` here?
 
-    function IRCode(stmts::InstructionStream, cfg::CFG, debuginfo::DebugInfoStream, argtypes::Vector{Any}, meta::Vector{Expr}, sptypes::Vector{VarState})
-        return new(stmts, argtypes, sptypes, debuginfo, cfg, NewNodeStream(), meta)
+    function IRCode(stmts::InstructionStream, cfg::CFG, debuginfo::DebugInfoStream,
+                    argtypes::Vector{Any}, meta::Vector{Expr}, sptypes::Vector{VarState},
+                    assume_bindings_static::Bool=false)
+        return new(stmts, argtypes, sptypes, debuginfo, cfg, NewNodeStream(), meta, assume_bindings_static)
     end
     function IRCode(ir::IRCode, stmts::InstructionStream, cfg::CFG, new_nodes::NewNodeStream)
         di = ir.debuginfo
         @assert di.codelocs === stmts.line
-        return new(stmts, ir.argtypes, ir.sptypes, di, cfg, new_nodes, ir.meta)
+        return new(stmts, ir.argtypes, ir.sptypes, di, cfg, new_nodes, ir.meta, ir.assume_bindings_static)
     end
     global function copy(ir::IRCode)
         di = ir.debuginfo
         stmts = copy(ir.stmts)
         di = copy(di)
         di.edges = copy(di.edges)
         di.codelocs = stmts.line
-        return new(stmts, copy(ir.argtypes), copy(ir.sptypes), di, copy(ir.cfg), copy(ir.new_nodes), copy(ir.meta))
+        return new(stmts, copy(ir.argtypes), copy(ir.sptypes), di, copy(ir.cfg),
+                   copy(ir.new_nodes), copy(ir.meta), ir.assume_bindings_static)
     end
 end
 

base/compiler/ssair/verify.jl

@@ -56,7 +56,7 @@ function check_op(ir::IRCode, domtree::DomTree, @nospecialize(op), use_bb::Int,
             error("")
         end
     elseif isa(op, GlobalRef)
-        if !isdefined(op.mod, op.name) || !isconst(op.mod, op.name)
+        if !(assume_bindings_static(ir) ? isdefined_globalref(op) : isdefinedconst_globalref(op))
             @verify_error "Unbound GlobalRef not allowed in value position"
             error("")
         end