wasm-emscripten-finalize: import env.STACKTOP, like asm2wasm does

src/tools/wasm-emscripten-finalize.cpp

@@ -187,6 +187,7 @@ int main(int argc, const char *argv[]) {
   } else {
     generator.generateRuntimeFunctions();
     generator.generateMemoryGrowthFunction();
+    generator.generateStackInitialization();
     // emscripten calls this by default for side libraries so we only need
     // to include in as a static ctor for main module case.
     if (wasm.getExportOrNull("__post_instantiate")) {

src/wasm-emscripten.h

@@ -36,6 +36,7 @@ class EmscriptenGlueGenerator {
 
   void generateRuntimeFunctions();
   Function* generateMemoryGrowthFunction();
+  void generateStackInitialization();
 
   // Create thunks for use with emscripten Runtime.dynCall. Creates one for each
   // signature in the indirect function table.

src/wasm/wasm-emscripten.cpp

@@ -36,6 +36,7 @@ cashew::IString EM_JS_PREFIX("__em_js__");
 static Name STACK_SAVE("stackSave"),
             STACK_RESTORE("stackRestore"),
             STACK_ALLOC("stackAlloc"),
+            STACK_INIT("stack$init"),
             DUMMY_FUNC("__wasm_nullptr");
 
 void addExportedFunction(Module& wasm, Function* function) {
@@ -155,6 +156,21 @@ Function* EmscriptenGlueGenerator::generateMemoryGrowthFunction() {
   return growFunction;
 }
 
+void EmscriptenGlueGenerator::generateStackInitialization() {
+  // Replace a global with a constant initial value with an imported
+  // initial value, which emscripten JS will send us.
+  // TODO: with mutable imported globals, we can avoid adding another
+  //       global for the import.
+  Builder builder(wasm);
+  auto* import = builder.makeGlobal(STACK_INIT, i32, nullptr, Builder::Immutable);
+  import->module = ENV;
+  import->base = STACKTOP;
+  wasm.addGlobal(import);
+  auto* stackPointer = getStackPointerGlobal();
+  assert(stackPointer->init->is<Const>());
+  stackPointer->init = builder.makeGetGlobal(import->name, i32);
+}
+
 static bool hasI64ResultOrParam(FunctionType* ft) {
   if (ft->result == i64) return true;
   for (auto ty : ft->params) {
@@ -227,18 +243,18 @@ static Function* ensureFunctionImport(Module* module, Name name, std::string sig
 }
 
 struct RemoveStackPointer : public PostWalker<RemoveStackPointer> {
-  RemoveStackPointer(Global* StackPointer) : StackPointer(StackPointer) {}
+  RemoveStackPointer(Global* stackPointer) : stackPointer(stackPointer) {}
 
   void visitGetGlobal(GetGlobal* curr) {
-    if (getModule()->getGlobalOrNull(curr->name) == StackPointer) {
+    if (getModule()->getGlobalOrNull(curr->name) == stackPointer) {
       ensureFunctionImport(getModule(), STACK_SAVE, "i");
       if (!builder) builder = make_unique<Builder>(*getModule());
       replaceCurrent(builder->makeCall(STACK_SAVE, {}, i32));
     }
   }
 
   void visitSetGlobal(SetGlobal* curr) {
-    if (getModule()->getGlobalOrNull(curr->name) == StackPointer) {
+    if (getModule()->getGlobalOrNull(curr->name) == stackPointer) {
       ensureFunctionImport(getModule(), STACK_RESTORE, "vi");
       if (!builder) builder = make_unique<Builder>(*getModule());
       replaceCurrent(builder->makeCall(STACK_RESTORE, {curr->value}, none));
@@ -247,7 +263,7 @@ struct RemoveStackPointer : public PostWalker<RemoveStackPointer> {
 
 private:
   std::unique_ptr<Builder> builder;
-  Global* StackPointer;
+  Global* stackPointer;
 };
 
 void EmscriptenGlueGenerator::replaceStackPointerGlobal() {
@@ -833,7 +849,9 @@ std::string EmscriptenGlueGenerator::generateEmscriptenMetadata(
   meta << "  \"externs\": [";
   commaFirst = true;
   ModuleUtils::iterImportedGlobals(wasm, [&](Global* import) {
-    meta << nextElement() << "\"_" << import->base.str << '"';
+    if (!(import->module == ENV && import->name == STACK_INIT)) {
+      meta << nextElement() << "\"_" << import->base.str << '"';
+    }
   });
   meta << "\n  ],\n";
 

test/lld/duplicate_imports.wast.out

@@ -9,14 +9,15 @@
  (type $legaltype$puts2 (func (param i32 i32) (result i32)))
  (type $legaltype$invoke_ffd (func (param i32 f64 f64) (result f64)))
  (type $legaltype$invoke_ffd2 (func (param i32 f64 f64) (result f64)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "puts" (func $puts1 (param i32) (result i32)))
  (import "env" "puts" (func $legalimport$puts2 (param i32 i32) (result i32)))
  (import "env" "invoke_ffd" (func $legalimport$invoke_ffd (param i32 f64 f64) (result f64)))
  (import "env" "invoke_ffd" (func $legalimport$invoke_ffd2 (param i32 f64 f64) (result f64)))
  (memory $0 2)
  (data (i32.const 568) "Hello, world\00")
  (table $0 1 1 anyfunc)
- (global $global$0 (mut i32) (i32.const 66128))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

test/lld/em_asm.wast.out

@@ -7,13 +7,14 @@
  (type $FUNCSIG$ii (func (param i32) (result i32)))
  (type $FUNCSIG$iiii (func (param i32 i32 i32) (result i32)))
  (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "emscripten_asm_const_i" (func $emscripten_asm_const_i (param i32) (result i32)))
  (import "env" "emscripten_asm_const_iii" (func $emscripten_asm_const_iii (param i32 i32 i32) (result i32)))
  (import "env" "emscripten_asm_const_ii" (func $emscripten_asm_const_ii (param i32 i32) (result i32)))
  (memory $0 2)
  (data (i32.const 568) "{ Module.print(\"Hello world\"); }\00{ return $0 + $1; }\00{ Module.print(\"Got \" + $0); }\00")
  (table $0 1 1 anyfunc)
- (global $global$0 (mut i32) (i32.const 66192))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66192))
  (global $global$2 i32 (i32.const 652))
  (export "memory" (memory $0))

test/lld/em_asm_table.wast.out

@@ -4,11 +4,12 @@
  (type $FUNCSIG$vii (func (param i32 i32)))
  (type $FUNCSIG$iiii (func (param i32 i32 i32) (result i32)))
  (import "env" "memory" (memory $0 8192))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "emscripten_log" (func $fimport$0 (param i32 i32)))
  (import "env" "emscripten_asm_const_iii" (func $emscripten_asm_const_iii (param i32 i32 i32) (result i32)))
  (table $0 159609 anyfunc)
  (elem (i32.const 1) $fimport$0 $emscripten_asm_const_iii)
- (global $global$0 (mut i32) (i32.const 1024))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 1048))
  (export "__data_end" (global $global$1))
  (export "stackSave" (func $stackSave))

test/lld/hello_world.wast.mem.out

@@ -3,10 +3,11 @@
  (type $1 (func (result i32)))
  (type $2 (func))
  (type $FUNCSIG$ii (func (param i32) (result i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "puts" (func $puts (param i32) (result i32)))
  (memory $0 2)
  (table $0 1 1 anyfunc)
- (global $global$0 (mut i32) (i32.const 66128))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

test/lld/hello_world.wast.out

@@ -3,11 +3,12 @@
  (type $1 (func (result i32)))
  (type $2 (func))
  (type $FUNCSIG$ii (func (param i32) (result i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "puts" (func $puts (param i32) (result i32)))
  (memory $0 2)
  (data (i32.const 568) "Hello, world\00")
  (table $0 1 1 anyfunc)
- (global $global$0 (mut i32) (i32.const 66128))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

test/lld/init.wast.out

@@ -1,10 +1,11 @@
 (module
  (type $0 (func))
  (type $1 (func (result i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (memory $0 2)
  (data (i32.const 568) "\00\00\00\00\00\00\00\00")
  (table $0 1 1 anyfunc)
- (global $global$0 (mut i32) (i32.const 66112))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66112))
  (global $global$2 i32 (i32.const 576))
  (export "memory" (memory $0))

test/lld/recursive.wast.out

@@ -3,11 +3,12 @@
  (type $1 (func (result i32)))
  (type $2 (func))
  (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "printf" (func $printf (param i32 i32) (result i32)))
  (memory $0 2)
  (data (i32.const 568) "%d:%d\n\00Result: %d\n\00")
  (table $0 1 1 anyfunc)
- (global $global$0 (mut i32) (i32.const 66128))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 587))
  (export "memory" (memory $0))

test/lld/reserved_func_ptr.wast.jscall.out

@@ -18,6 +18,7 @@
  (type $FUNCSIG$v (func))
  (type $FUNCSIG$vii (func (param i32 i32)))
  (type $FUNCSIG$viiii (func (param i32 i32 i32 i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "_Z4atoiPKc" (func $_Z4atoiPKc (param i32) (result i32)))
  (import "env" "jsCall_ddi" (func $jsCall_ddi (param i32 f64 i32) (result f64)))
  (import "env" "jsCall_fffi" (func $jsCall_fffi (param i32 f32 f32 i32) (result f32)))
@@ -28,7 +29,7 @@
  (memory $0 2)
  (table $0 21 21 anyfunc)
  (elem (i32.const 1) $_Z18address_taken_funciii $_Z19address_taken_func2iii $jsCall_ddi_0 $jsCall_ddi_1 $jsCall_ddi_2 $jsCall_fffi_0 $jsCall_fffi_1 $jsCall_fffi_2 $jsCall_iii_0 $jsCall_iii_1 $jsCall_iii_2 $jsCall_v_0 $jsCall_v_1 $jsCall_v_2 $jsCall_vi_0 $jsCall_vi_1 $jsCall_vi_2 $jsCall_viii_0 $jsCall_viii_1 $jsCall_viii_2)
- (global $global$0 (mut i32) (i32.const 66112))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66112))
  (global $global$2 i32 (i32.const 568))
  (export "memory" (memory $0))

test/lld/reserved_func_ptr.wast.out

@@ -8,11 +8,12 @@
  (type $6 (func (param i32) (result i32)))
  (type $FUNCSIG$ii (func (param i32) (result i32)))
  (type $FUNCSIG$viii (func (param i32 i32 i32)))
+ (import "env" "STACKTOP" (global $stack$init i32))
  (import "env" "_Z4atoiPKc" (func $_Z4atoiPKc (param i32) (result i32)))
  (memory $0 2)
  (table $0 3 3 anyfunc)
  (elem (i32.const 1) $_Z18address_taken_funciii $_Z19address_taken_func2iii)
- (global $global$0 (mut i32) (i32.const 66112))
+ (global $global$0 (mut i32) (get_global $stack$init))
  (global $global$1 i32 (i32.const 66112))
  (global $global$2 i32 (i32.const 568))
  (export "memory" (memory $0))