codegen: remove readonly from abstract type calling convention

Fix some misuses of `jl_is_immutable_datatype`, and rename it to
indicate it is not a guarantee of immutable.

Refs: #58070

The cfunction code difference isn't normally emitted by codegen since it
is just a fallback, but can be observed with various code_llvm type
signatures for various combinations of abstract/union/concrete/mutable:

   f(x::T) where {T} = @cfunction identity Ref{T} (Ref{T},)
   code_llvm(f, (Any,), dump_module=true, raw=true)
   code_llvm(f, (Number,), dump_module=true, raw=true)
   code_llvm(f, (Union{Int32,Int64},), dump_module=true, raw=true)
   code_llvm(f, (Complex,), dump_module=true, raw=true)
   code_llvm(f, (Ref{Int},), dump_module=true, raw=true)

Author: vtjnash

Compiler/test/codegen.jl

@@ -1033,3 +1033,7 @@ end
 const x57872 = "Hello"
 f57872() = (Core.isdefinedglobal(@__MODULE__, Base.compilerbarrier(:const, :x57872)), x57872) # Extra globalref here to force world age bounds
 @test f57872() == (true, "Hello")
+
+@noinline f_mutateany(@nospecialize x) = x[] = 1
+g_mutateany() = (y = Ref(0); f_mutateany(y); y[])
+@test g_mutateany() === 1

src/cgutils.cpp

@@ -1479,6 +1479,7 @@ static Value *emit_sizeof(jl_codectx_t &ctx, const jl_cgval_t &p)
         return dyn_size;
     }
 }
+*/
 
 static Value *emit_datatype_mutabl(jl_codectx_t &ctx, Value *dt)
 {
@@ -1493,7 +1494,6 @@ static Value *emit_datatype_mutabl(jl_codectx_t &ctx, Value *dt)
     mutabl = ctx.builder.CreateLShr(mutabl, 1);
     return ctx.builder.CreateTrunc(mutabl, getInt1Ty(ctx.builder.getContext()));
 }
-*/
 
 static Value *emit_datatype_isprimitivetype(jl_codectx_t &ctx, Value *typ)
 {

src/codegen.cpp

@@ -1600,7 +1600,7 @@ static MDNode *best_tbaa(jl_tbaacache_t &tbaa_cache, jl_value_t *jt) {
 // note that this includes jl_isbits, although codegen should work regardless
 static bool jl_is_concrete_immutable(jl_value_t* t)
 {
-    return jl_is_immutable_datatype(t) && ((jl_datatype_t*)t)->isconcretetype;
+    return jl_may_be_immutable_datatype(t) && ((jl_datatype_t*)t)->isconcretetype;
 }
 
 static bool jl_is_pointerfree(jl_value_t* t)
@@ -7385,8 +7385,8 @@ static Function *gen_cfun_wrapper(
                     inputarg = mark_julia_type(ctx, val, false, jargty);
                 }
             }
-            else if (static_at || (!jl_is_typevar(jargty) && !jl_is_immutable_datatype(jargty))) {
-                // must be a jl_value_t* (because it's mutable or contains gc roots)
+            else if (static_at || (!jl_is_typevar(jargty) && (!jl_is_datatype(jargty) || jl_is_abstracttype(jargty) || jl_is_mutable_datatype(jargty)))) {
+                // must be a jl_value_t* (because it is mutable or abstract)
                 inputarg = mark_julia_type(ctx, maybe_decay_untracked(ctx, val), true, jargty_proper);
             }
             else {
@@ -7400,31 +7400,36 @@ static Function *gen_cfun_wrapper(
                         emit_ptrgep(ctx, nestPtr, jl_array_nrows(*closure_types) * ctx.types().sizeof_ptr),
                         Align(sizeof(void*)));
                 BasicBlock *boxedBB = BasicBlock::Create(ctx.builder.getContext(), "isboxed", cw);
-                BasicBlock *loadBB = BasicBlock::Create(ctx.builder.getContext(), "need-load", cw);
+                BasicBlock *notanyBB = BasicBlock::Create(ctx.builder.getContext(), "not-any", cw);
                 BasicBlock *unboxedBB = BasicBlock::Create(ctx.builder.getContext(), "maybe-unboxed", cw);
                 BasicBlock *isanyBB = BasicBlock::Create(ctx.builder.getContext(), "any", cw);
                 BasicBlock *afterBB = BasicBlock::Create(ctx.builder.getContext(), "after", cw);
-                Value *isrtboxed = ctx.builder.CreateIsNull(val); // XXX: this is the wrong condition and should be inspecting runtime_dt instead
-                ctx.builder.CreateCondBr(isrtboxed, boxedBB, loadBB);
-                ctx.builder.SetInsertPoint(boxedBB);
-                Value *p1 = val;
-                p1 = track_pjlvalue(ctx, p1);
-                ctx.builder.CreateBr(afterBB);
-                ctx.builder.SetInsertPoint(loadBB);
                 Value *isrtany = ctx.builder.CreateICmpEQ(
-                        literal_pointer_val(ctx, (jl_value_t*)jl_any_type), val);
-                ctx.builder.CreateCondBr(isrtany, isanyBB, unboxedBB);
+                        track_pjlvalue(ctx,literal_pointer_val(ctx, (jl_value_t*)jl_any_type)), runtime_dt);
+                ctx.builder.CreateCondBr(isrtany, isanyBB, notanyBB);
                 ctx.builder.SetInsertPoint(isanyBB);
-                Value *p2 = ctx.builder.CreateAlignedLoad(ctx.types().T_prjlvalue, val, Align(sizeof(void*)));
+                Value *p1 = ctx.builder.CreateAlignedLoad(ctx.types().T_prjlvalue, val, Align(sizeof(void*)));
+                ctx.builder.CreateBr(afterBB);
+                isanyBB = ctx.builder.GetInsertBlock(); // could have changed
+                ctx.builder.SetInsertPoint(notanyBB);
+                jl_cgval_t runtime_dt_val = mark_julia_type(ctx, runtime_dt, true, jl_any_type);
+                Value *isrtboxed = // (!jl_is_datatype(runtime_dt) || !jl_is_concrete_datatype(runtime_dt) || jl_is_mutable_datatype(runtime_dt))
+                    emit_guarded_test(ctx, emit_exactly_isa(ctx, runtime_dt_val, jl_datatype_type), true, [&] {
+                            return ctx.builder.CreateOr(ctx.builder.CreateNot(emit_isconcrete(ctx, runtime_dt)), emit_datatype_mutabl(ctx, runtime_dt));
+                    });
+                ctx.builder.CreateCondBr(isrtboxed, boxedBB, unboxedBB);
+                ctx.builder.SetInsertPoint(boxedBB);
+                Value *p2 = track_pjlvalue(ctx, val);
                 ctx.builder.CreateBr(afterBB);
+                boxedBB = ctx.builder.GetInsertBlock(); // could have changed
                 ctx.builder.SetInsertPoint(unboxedBB);
                 Value *p3 = emit_new_bits(ctx, runtime_dt, val);
                 unboxedBB = ctx.builder.GetInsertBlock(); // could have changed
                 ctx.builder.CreateBr(afterBB);
                 ctx.builder.SetInsertPoint(afterBB);
                 PHINode *p = ctx.builder.CreatePHI(ctx.types().T_prjlvalue, 3);
-                p->addIncoming(p1, boxedBB);
-                p->addIncoming(p2, isanyBB);
+                p->addIncoming(p1, isanyBB);
+                p->addIncoming(p2, boxedBB);
                 p->addIncoming(p3, unboxedBB);
                 inputarg = mark_julia_type(ctx, p, true, jargty_proper);
             }
@@ -7975,7 +7980,7 @@ static jl_returninfo_t get_specsig_function(jl_codegen_params_t &params, Module
             param.addAttribute(Attribute::ReadOnly);
             ty = PointerType::get(M->getContext(), AddressSpace::Derived);
         }
-        else if (isboxed && jl_is_immutable_datatype(jt)) {
+        else if (isboxed && jl_may_be_immutable_datatype(jt) && !jl_is_abstracttype(jt)) {
             param.addAttribute(Attribute::ReadOnly);
         }
         else if (jl_is_primitivetype(jt) && ty->isIntegerTy()) {

src/julia.h

@@ -1620,7 +1620,7 @@ static inline int jl_field_isconst(jl_datatype_t *st, int i) JL_NOTSAFEPOINT
 #define jl_is_mutable(t)     (((jl_datatype_t*)t)->name->mutabl)
 #define jl_is_mutable_datatype(t) (jl_is_datatype(t) && (((jl_datatype_t*)t)->name->mutabl))
 #define jl_is_immutable(t)   (!((jl_datatype_t*)t)->name->mutabl)
-#define jl_is_immutable_datatype(t) (jl_is_datatype(t) && (!((jl_datatype_t*)t)->name->mutabl))
+#define jl_may_be_immutable_datatype(t) (jl_is_datatype(t) && (!((jl_datatype_t*)t)->name->mutabl))
 #define jl_is_uniontype(v)   jl_typetagis(v,jl_uniontype_tag<<4)
 #define jl_is_typevar(v)     jl_typetagis(v,jl_tvar_tag<<4)
 #define jl_is_unionall(v)    jl_typetagis(v,jl_unionall_tag<<4)