add the ability to specify the external name of a ccallable (#57763)

This will allow exporting julia `main` as something else so a separate
native `main` can be written to handle initialization. I'm sure it will
have lots of other uses too though.

Author: JeffBezanson

Compiler/src/typeinfer.jl

@@ -1371,8 +1371,7 @@ function typeinf_ext_toplevel(methods::Vector{Any}, worlds::Vector{UInt}, trim_m
                 end
                 # additionally enqueue the ccallable entrypoint / adapter, which implicitly
                 # invokes the above ci
-                push!(codeinfos, rt)
-                push!(codeinfos, sig)
+                push!(codeinfos, item)
             end
         end
         while !isempty(tocompile)

Compiler/src/verifytrim.jl

@@ -256,7 +256,7 @@ function get_verify_typeinf_trim(codeinfos::Vector{Any})
     caches = IdDict{MethodInstance,CodeInstance}()
     errors = ErrorList()
     parents = ParentMap()
-    for i = 1:2:length(codeinfos)
+    for i = 1:length(codeinfos)
         item = codeinfos[i]
         if item isa CodeInstance
             push!(inspected, item)
@@ -268,14 +268,14 @@ function get_verify_typeinf_trim(codeinfos::Vector{Any})
             end
         end
     end
-    for i = 1:2:length(codeinfos)
+    for i = 1:length(codeinfos)
         item = codeinfos[i]
         if item isa CodeInstance
             src = codeinfos[i + 1]::CodeInfo
             verify_codeinstance!(item, src, inspected, caches, parents, errors)
-        else
-            rt = item::Type
-            sig = codeinfos[i + 1]::Type
+        elseif item isa SimpleVector
+            rt = item[1]::Type
+            sig = item[2]::Type
             ptr = ccall(:jl_get_specialization1,
                         #= MethodInstance =# Ptr{Cvoid}, (Any, Csize_t, Cint),
                         sig, this_world, #= mt_cache =# 0)

Compiler/test/verifytrim.jl

@@ -44,8 +44,8 @@ let infos = typeinf_ext_toplevel(Any[Core.svec(Base.SecretBuffer, Tuple{Type{Bas
 
             $""", repr)
 
-    resize!(infos, 2)
-    @test infos[1] isa Type && infos[2] isa Type
+    resize!(infos, 1)
+    @test infos[1] isa Core.SimpleVector && infos[1][1] isa Type && infos[1][2] isa Type
     errors, parents = get_verify_typeinf_trim(infos)
     desc = only(errors)
     @test !desc.first

base/c.jl

@@ -203,11 +203,11 @@ function exit_on_sigint(on::Bool)
     ccall(:jl_exit_on_sigint, Cvoid, (Cint,), on)
 end
 
-function _ccallable(rt::Type, sigt::Type)
-    ccall(:jl_extern_c, Cvoid, (Any, Any), rt, sigt)
+function _ccallable(name::Union{Nothing, String}, rt::Type, sigt::Type)
+    ccall(:jl_extern_c, Cvoid, (Any, Any, Any), name, rt, sigt)
 end
 
-function expand_ccallable(rt, def)
+function expand_ccallable(name, rt, def)
     if isa(def,Expr) && (def.head === :(=) || def.head === :function)
         sig = def.args[1]
         if sig.head === :(::)
@@ -235,24 +235,30 @@ function expand_ccallable(rt, def)
             end
             return quote
                 @__doc__ $(esc(def))
-                _ccallable($(esc(rt)), $(Expr(:curly, :Tuple, esc(f), map(esc, at)...)))
+                _ccallable($name, $(esc(rt)), $(Expr(:curly, :Tuple, esc(f), map(esc, at)...)))
             end
         end
     end
     error("expected method definition in @ccallable")
 end
 
 """
-    @ccallable(def)
+    @ccallable ["name"] function f(...)::RetType ... end
 
 Make the annotated function be callable from C using its name. This can, for example,
-be used to expose functionality as a C-API when creating a custom Julia sysimage.
+be used to expose functionality as a C API when creating a custom Julia sysimage.
+
+If the first argument is a string, it is used as the external name of the function.
 """
 macro ccallable(def)
-    expand_ccallable(nothing, def)
+    expand_ccallable(nothing, nothing, def)
 end
 macro ccallable(rt, def)
-    expand_ccallable(rt, def)
+    if rt isa String
+        expand_ccallable(rt, nothing, def)
+    else
+        expand_ccallable(nothing, rt, def)
+    end
 end
 
 # @ccall implementation

src/aotcompile.cpp

@@ -784,9 +784,12 @@ void *jl_emit_native_impl(jl_array_t *codeinfos, LLVMOrcThreadSafeModuleRef llvm
                 compiled_functions[codeinst] = {std::move(result_m), std::move(decls)};
         }
         else {
-            jl_value_t *sig = jl_array_ptr_ref(codeinfos, ++i);
-            assert(jl_is_type(item) && jl_is_type(sig));
-            jl_generate_ccallable(clone.getModuleUnlocked(), nullptr, item, sig, params);
+            assert(jl_is_simplevector(item));
+            jl_value_t *rt = jl_svecref(item, 0);
+            jl_value_t *sig = jl_svecref(item, 1);
+            jl_value_t *nameval = jl_svec_len(item) == 2 ? jl_nothing : jl_svecref(item, 2);
+            assert(jl_is_type(rt) && jl_is_type(sig));
+            jl_generate_ccallable(clone.getModuleUnlocked(), nameval, rt, sig, params);
         }
     }
     // finally, make sure all referenced methods get fixed up, particularly if the user declined to compile them

src/codegen-stubs.c

@@ -70,7 +70,7 @@ JL_DLLEXPORT uint32_t jl_get_LLVM_VERSION_fallback(void)
     return 0;
 }
 
-JL_DLLEXPORT int jl_compile_extern_c_fallback(LLVMOrcThreadSafeModuleRef llvmmod, void *params, void *sysimg, jl_value_t *declrt, jl_value_t *sigt)
+JL_DLLEXPORT int jl_compile_extern_c_fallback(LLVMOrcThreadSafeModuleRef llvmmod, void *params, void *sysimg, jl_value_t *name, jl_value_t *declrt, jl_value_t *sigt)
 {
     // Assume we were able to register the ccallable with the JIT. The
     // fact that we didn't is not observable since we cannot compile

src/codegen.cpp

@@ -7709,14 +7709,14 @@ static jl_cgval_t emit_cfunction(jl_codectx_t &ctx, jl_value_t *output_type, con
 
 // do codegen to create a C-callable alias/wrapper, or if sysimg_handle is set,
 // restore one from a loaded system image.
-const char *jl_generate_ccallable(Module *llvmmod, void *sysimg_handle, jl_value_t *declrt, jl_value_t *sigt, jl_codegen_params_t &params)
+const char *jl_generate_ccallable(Module *llvmmod, jl_value_t *nameval, jl_value_t *declrt, jl_value_t *sigt, jl_codegen_params_t &params)
 {
     ++GeneratedCCallables;
     jl_datatype_t *ft = (jl_datatype_t*)jl_tparam0(sigt);
     assert(jl_is_datatype(ft));
     jl_value_t *ff = ft->instance;
     assert(ff);
-    const char *name = jl_symbol_name(ft->name->mt->name);
+    const char *name = !jl_is_string(nameval) ? jl_symbol_name(ft->name->mt->name) : jl_string_data(nameval);
     jl_value_t *crt = declrt;
     if (jl_is_abstract_ref_type(declrt)) {
         declrt = jl_tparam0(declrt);
@@ -7738,25 +7738,12 @@ const char *jl_generate_ccallable(Module *llvmmod, void *sysimg_handle, jl_value
         function_sig_t sig("cfunction", lcrt, crt, toboxed, false,
                            argtypes, NULL, false, CallingConv::C, false, &params);
         if (sig.err_msg.empty()) {
-            if (sysimg_handle) {
-                // restore a ccallable from the system image
-                void *addr;
-                int found = jl_dlsym(sysimg_handle, name, &addr, 0);
-                if (found)
-                    add_named_global(name, addr);
-                else {
-                    err = jl_get_exceptionf(jl_errorexception_type, "%s not found in sysimg", name);
-                    jl_throw(err);
-                }
-            }
-            else {
-                //Safe b/c params holds context lock
-                Function *cw = gen_cfun_wrapper(llvmmod, params, sig, ff, name, declrt, sigt, NULL, NULL, NULL);
-                auto alias = GlobalAlias::create(cw->getValueType(), cw->getType()->getAddressSpace(),
-                                    GlobalValue::ExternalLinkage, name, cw, llvmmod);
-                if (params.TargetTriple.isOSBinFormatCOFF()) {
-                    alias->setDLLStorageClass(GlobalValue::DLLStorageClassTypes::DLLExportStorageClass);
-                }
+            //Safe b/c params holds context lock
+            Function *cw = gen_cfun_wrapper(llvmmod, params, sig, ff, name, declrt, sigt, NULL, NULL, NULL);
+            auto alias = GlobalAlias::create(cw->getValueType(), cw->getType()->getAddressSpace(),
+                                GlobalValue::ExternalLinkage, name, cw, llvmmod);
+            if (params.TargetTriple.isOSBinFormatCOFF()) {
+                alias->setDLLStorageClass(GlobalValue::DLLStorageClassTypes::DLLExportStorageClass);
             }
             JL_GC_POP();
             return name;

src/gf.c

@@ -4596,7 +4596,7 @@ JL_DLLEXPORT void jl_typeinf_timing_end(uint64_t start, int is_recompile)
 }
 
 // declare a C-callable entry point; called during code loading from the toplevel
-JL_DLLEXPORT void jl_extern_c(jl_value_t *declrt, jl_tupletype_t *sigt)
+JL_DLLEXPORT void jl_extern_c(jl_value_t *name, jl_value_t *declrt, jl_tupletype_t *sigt)
 {
     // validate arguments. try to do as many checks as possible here to avoid
     // throwing errors later during codegen.
@@ -4627,7 +4627,10 @@ JL_DLLEXPORT void jl_extern_c(jl_value_t *declrt, jl_tupletype_t *sigt)
     if (!jl_is_method(meth))
         jl_error("@ccallable: could not find requested method");
     JL_GC_PUSH1(&meth);
-    meth->ccallable = jl_svec2(declrt, (jl_value_t*)sigt);
+    if (name == jl_nothing)
+        meth->ccallable = jl_svec2(declrt, (jl_value_t*)sigt);
+    else
+        meth->ccallable = jl_svec3(declrt, (jl_value_t*)sigt, name);
     jl_gc_wb(meth, meth->ccallable);
     JL_GC_POP();
 }

src/jitlayers.h

@@ -284,7 +284,7 @@ struct jl_codegen_params_t {
     ~jl_codegen_params_t() JL_NOTSAFEPOINT JL_NOTSAFEPOINT_LEAVE = default;
 };
 
-const char *jl_generate_ccallable(Module *llvmmod, void *sysimg_handle, jl_value_t *declrt, jl_value_t *sigt, jl_codegen_params_t &params);
+const char *jl_generate_ccallable(Module *llvmmod, jl_value_t *nameval, jl_value_t *declrt, jl_value_t *sigt, jl_codegen_params_t &params);
 
 jl_llvm_functions_t jl_emit_code(
         orc::ThreadSafeModule &M,

src/julia.h

@@ -1925,6 +1925,7 @@ JL_DLLEXPORT jl_method_instance_t *jl_new_method_instance_uninit(void);
 JL_DLLEXPORT jl_svec_t *jl_svec(size_t n, ...) JL_MAYBE_UNROOTED;
 JL_DLLEXPORT jl_svec_t *jl_svec1(void *a);
 JL_DLLEXPORT jl_svec_t *jl_svec2(void *a, void *b);
+JL_DLLEXPORT jl_svec_t *jl_svec3(void *a, void *b, void *c);
 JL_DLLEXPORT jl_svec_t *jl_alloc_svec(size_t n);
 JL_DLLEXPORT jl_svec_t *jl_alloc_svec_uninit(size_t n);
 JL_DLLEXPORT jl_svec_t *jl_svec_copy(jl_svec_t *a);