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stage1: Disambiguate Wasm imports with same name

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Closes #7088
This commit is contained in:
LemonBoy 2020-11-12 20:16:58 +01:00 committed by Andrew Kelley
parent c4fd3fc270
commit 211feea914
1 changed files with 33 additions and 6 deletions
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39
src/stage1/codegen.cpp
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@ -380,9 +380,36 @@ static LLVMValueRef make_fn_llvm_value(CodeGen *g, ZigFn *fn) {
LLVMTypeRef fn_llvm_type = fn->raw_type_ref;
LLVMValueRef llvm_fn = nullptr;
if (fn->body_node == nullptr) {
assert(fn->proto_node->type == NodeTypeFnProto);
AstNodeFnProto *fn_proto = &fn->proto_node->data.fn_proto;
const unsigned fn_addrspace = ZigLLVMDataLayoutGetProgramAddressSpace(g->target_data_ref);
// The compiler tries to deduplicate extern definitions by looking up
// their name, this was introduced to allow the declaration of the same
// extern function with differing prototypes.
// When Wasm is targeted this check becomes a problem as the user may
// declare two (or more) extern functions sharing the same name but
// imported from different modules!
// To overcome this problem we generate a mangled identifier out of the
// import and the function name, this name is only visible within the
// compiler as we're telling LLVM (using 'wasm-import-name' and
// 'wasm-import-name') what the real function name is and where to find
// it.
const bool use_mangled_name = target_is_wasm(g->zig_target) &&
fn_proto->is_extern && fn_proto->lib_name != nullptr;
// Pick a weird name to avoid collisions...
// This whole function should be burned to the ground.
Buf *mangled_symbol_buf = use_mangled_name ?
buf_sprintf("%s|%s", unmangled_name, buf_ptr(fn_proto->lib_name)) :
nullptr;
symbol_name = use_mangled_name ?
buf_ptr(mangled_symbol_buf) : unmangled_name;
LLVMValueRef existing_llvm_fn = LLVMGetNamedFunction(g->module, symbol_name);
if (existing_llvm_fn) {
if (mangled_symbol_buf) buf_destroy(mangled_symbol_buf);
return LLVMConstBitCast(existing_llvm_fn, LLVMPointerType(fn_llvm_type, fn_addrspace));
} else {
Buf *buf_symbol_name = buf_create_from_str(symbol_name);
@ -392,12 +419,9 @@ static LLVMValueRef make_fn_llvm_value(CodeGen *g, ZigFn *fn) {
if (entry == nullptr) {
llvm_fn = LLVMAddFunction(g->module, symbol_name, fn_llvm_type);
if (target_is_wasm(g->zig_target)) {
assert(fn->proto_node->type == NodeTypeFnProto);
AstNodeFnProto *fn_proto = &fn->proto_node->data.fn_proto;
if (fn_proto-> is_extern && fn_proto->lib_name != nullptr ) {
addLLVMFnAttrStr(llvm_fn, "wasm-import-module", buf_ptr(fn_proto->lib_name));
}
if (use_mangled_name) {
addLLVMFnAttrStr(llvm_fn, "wasm-import-name", unmangled_name);
addLLVMFnAttrStr(llvm_fn, "wasm-import-module", buf_ptr(fn_proto->lib_name));
}
} else {
assert(entry->value->id == TldIdFn);
@ -407,8 +431,11 @@ static LLVMValueRef make_fn_llvm_value(CodeGen *g, ZigFn *fn) {
tld_fn->fn_entry->llvm_value = LLVMAddFunction(g->module, symbol_name,
tld_fn->fn_entry->raw_type_ref);
llvm_fn = LLVMConstBitCast(tld_fn->fn_entry->llvm_value, LLVMPointerType(fn_llvm_type, fn_addrspace));
if (mangled_symbol_buf) buf_destroy(mangled_symbol_buf);
return llvm_fn;
}
if (mangled_symbol_buf) buf_destroy(mangled_symbol_buf);
}
} else {
if (llvm_fn == nullptr) {