diff options
| -rw-r--r-- | src/wasm/wasm-emscripten.cpp | 29 | ||||
| -rw-r--r-- | test/lld/shared.wast.out | 6 |
2 files changed, 28 insertions, 7 deletions
diff --git a/src/wasm/wasm-emscripten.cpp b/src/wasm/wasm-emscripten.cpp index 875212c44..95566f5b9 100644 --- a/src/wasm/wasm-emscripten.cpp +++ b/src/wasm/wasm-emscripten.cpp @@ -48,9 +48,19 @@ void addExportedFunction(Module& wasm, Function* function) { wasm.addExport(export_); } +// TODO(sbc): There should probably be a better way to do this. +bool isExported(Module& wasm, Name name) { + for (auto& ex : wasm.exports) { + if (ex->value == name) { + return true; + } + } + return false; +} + Global* EmscriptenGlueGenerator::getStackPointerGlobal() { // Assumption: The stack pointer is either imported as __stack_pointer or - // its the first non-imported global. + // its the first non-imported and non-exported global. // TODO(sbc): Find a better way to discover the stack pointer. Perhaps the // linker could export it by name? for (auto& g : wasm.globals) { @@ -58,7 +68,7 @@ Global* EmscriptenGlueGenerator::getStackPointerGlobal() { if (g->base == "__stack_pointer") { return g.get(); } - } else { + } else if (!isExported(wasm, g->name)) { return g.get(); } } @@ -172,6 +182,17 @@ static Function* ensureFunctionImport(Module* module, Name name, std::string sig return import; } +// Convert LLVM PIC ABI to emscripten ABI +// +// When generating -fPIC code llvm will generate imports call GOT.mem and +// GOT.func in order to access the addresses of external global data and +// functions. +// +// However emscripten uses a different ABI where function and data addresses +// are available at runtime via special `g$foo` and `fp$bar` function calls. +// +// Here we internalize all such wasm globals and generte code that sets their +// value based on the result of call `g$foo` and `fp$bar` functions at runtime. Function* EmscriptenGlueGenerator::generateAssignGOTEntriesFunction() { std::vector<Global*> got_entries_func; std::vector<Global*> got_entries_mem; @@ -209,7 +230,7 @@ Function* EmscriptenGlueGenerator::generateAssignGOTEntriesFunction() { } for (Global* g : got_entries_func) { - Name getter(std::string("f$") + g->base.c_str()); + Name getter(std::string("fp$") + g->base.c_str()); if (auto* f = wasm.getFunctionOrNull(g->base)) { getter.set((getter.c_str() + std::string("$") + getSig(f)).c_str(), false); } @@ -244,7 +265,7 @@ void EmscriptenGlueGenerator::generatePostInstantiateFunction() { if (Function* F = generateAssignGOTEntriesFunction()) { // call __assign_got_enties from post_instantiate Expression* call = builder.makeCall(F->name, {}, none); - post_instantiate->body = builder.blockify(call); + post_instantiate->body = builder.blockify(post_instantiate->body, call); } // The names of standard imports/exports used by lld doesn't quite match that diff --git a/test/lld/shared.wast.out b/test/lld/shared.wast.out index 597d7086d..965ba326b 100644 --- a/test/lld/shared.wast.out +++ b/test/lld/shared.wast.out @@ -11,7 +11,7 @@ (import "env" "__table_base" (global $gimport$3 i32)) (import "env" "puts" (func $puts (param i32) (result i32))) (import "env" "g$external_var" (func $g$external_var (result i32))) - (import "env" "f$puts$ii" (func $f$puts$ii (result i32))) + (import "env" "fp$puts$ii" (func $fp$puts$ii (result i32))) (global $gimport$5 (mut i32) (i32.const 0)) (global $gimport$6 (mut i32) (i32.const 0)) (export "print_message" (func $print_message)) @@ -42,7 +42,7 @@ (call $g$external_var) ) (global.set $gimport$5 - (call $f$puts$ii) + (call $fp$puts$ii) ) ) ) @@ -54,7 +54,7 @@ "declares": [ "puts", "g$external_var", - "f$puts$ii" + "fp$puts$ii" ], "externs": [ "___memory_base", |