Ignore --initial-stack-pointer arg to wasm-emscripten-finalize (#2201)

We were passing bad value in --initial-stack-pointer which did not
include the STATIC_BUMP (since STATIC_BUMP is determinted by the output
of finalize).

If emscripten wants to set the stack pointer position it can do
so by calling the stackRestore() function at startup.

This argument will be removed completely once we stop passing it on the
emscripten side.

See emscripten-core/emscripten#8905

Author: sbc100

CHANGELOG.md

@@ -15,6 +15,12 @@ full changeset diff at the end of each section.
 Current Trunk
 -------------
 
+v85
+---
+
+- The --initial-stack-pointer argument to wasm-emscripten-finalize no longer
+  has any effect.  It will be removed completely in future release.
+
 - Wast file parsing rules now don't allow a few invalid formats for typeuses
   that were previously allowed. Typeuse entries should follow this format,
   meaning they should have (type) -> (param) -> (result) order if more than one

scripts/test/lld.py

@@ -25,7 +25,7 @@ def args_for_finalize(filename):
    if 'shared' in filename:
      return ['--side-module']
    else:
-     return ['--global-base=568', '--initial-stack-pointer=16384']
+     return ['--global-base=568']
 
 
 def test_wasm_emscripten_finalize():

src/tools/wasm-emscripten-finalize.cpp

@@ -49,7 +49,6 @@ int main(int argc, const char* argv[]) {
   bool isSideModule = false;
   bool legalizeJavaScriptFFI = true;
   uint64_t globalBase = INVALID_BASE;
-  uint64_t initialStackPointer = INVALID_BASE;
   ToolOptions options("wasm-emscripten-finalize",
                       "Performs Emscripten-specific transforms on .wasm files");
   options
@@ -78,13 +77,13 @@ int main(int argc, const char* argv[]) {
          [&globalBase](Options*, const std::string& argument) {
            globalBase = std::stoull(argument);
          })
+    // TODO(sbc): Remove this one this argument is no longer passed by
+    // emscripten. See https://github.com/emscripten-core/emscripten/issues/8905
     .add("--initial-stack-pointer",
          "",
-         "The initial location of the stack pointer",
+         "ignored - will be removed in a future release",
          Options::Arguments::One,
-         [&initialStackPointer](Options*, const std::string& argument) {
-           initialStackPointer = std::stoull(argument);
-         })
+         [](Options*, const std::string& argument) {})
     .add("--side-module",
          "",
          "Input is an emscripten side module",
@@ -169,9 +168,6 @@ int main(int argc, const char* argv[]) {
     if (globalBase == INVALID_BASE) {
       Fatal() << "globalBase must be set";
     }
-    if (initialStackPointer == INVALID_BASE) {
-      Fatal() << "initialStackPointer must be set";
-    }
     Export* dataEndExport = wasm.getExport("__data_end");
     if (dataEndExport == nullptr) {
       Fatal() << "__data_end export not found";
@@ -210,7 +206,6 @@ int main(int argc, const char* argv[]) {
   } else {
     generator.generateRuntimeFunctions();
     generator.generateMemoryGrowthFunction();
-    generator.generateStackInitialization(initialStackPointer);
     // For side modules these gets called via __post_instantiate
     if (Function* F = generator.generateAssignGOTEntriesFunction()) {
       auto* ex = new Export();

src/wasm-emscripten.h

@@ -34,7 +34,6 @@ class EmscriptenGlueGenerator {
   void generateRuntimeFunctions();
   Function* generateMemoryGrowthFunction();
   Function* generateAssignGOTEntriesFunction();
-  void generateStackInitialization(Address addr);
   void generatePostInstantiateFunction();
 
   // Create thunks for use with emscripten Runtime.dynCall. Creates one for each

src/wasm/wasm-emscripten.cpp

@@ -311,15 +311,6 @@ Function* EmscriptenGlueGenerator::generateMemoryGrowthFunction() {
   return growFunction;
 }
 
-void EmscriptenGlueGenerator::generateStackInitialization(Address addr) {
-  auto* stackPointer = getStackPointerGlobal();
-  assert(!stackPointer->imported());
-  if (!stackPointer->init || !stackPointer->init->is<Const>()) {
-    Fatal() << "stack pointer global is not assignable";
-  }
-  stackPointer->init->cast<Const>()->value = Literal(int32_t(addr));
-}
-
 inline void exportFunction(Module& wasm, Name name, bool must_export) {
   if (!wasm.getFunctionOrNull(name)) {
     assert(!must_export);

test/lld/duplicate_imports.wast.out

@@ -13,7 +13,7 @@
  (memory $0 2)
  (data (i32.const 568) "Hello, world\00")
  (table $0 1 1 funcref)
- (global $global$0 (mut i32) (i32.const 16384))
+ (global $global$0 (mut i32) (i32.const 66128))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

test/lld/em_asm.wast.mem.out

@@ -10,7 +10,7 @@
  (import "env" "emscripten_asm_const_iii" (func $emscripten_asm_const_iii (param i32 i32 i32) (result i32)))
  (memory $0 2)
  (table $0 1 1 funcref)
- (global $global$0 (mut i32) (i32.const 16384))
+ (global $global$0 (mut i32) (i32.const 66192))
  (global $global$1 i32 (i32.const 66192))
  (global $global$2 i32 (i32.const 652))
  (export "memory" (memory $0))

test/lld/em_asm.wast.out

@@ -11,7 +11,7 @@
  (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 funcref)
- (global $global$0 (mut i32) (i32.const 16384))
+ (global $global$0 (mut i32) (i32.const 66192))
  (global $global$1 i32 (i32.const 66192))
  (global $global$2 i32 (i32.const 652))
  (export "memory" (memory $0))

test/lld/em_asm_O0.wast.out

@@ -13,7 +13,7 @@
  (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 funcref)
- (global $global$0 (mut i32) (i32.const 16384))
+ (global $global$0 (mut i32) (i32.const 66192))
  (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

@@ -8,7 +8,7 @@
  (import "env" "emscripten_asm_const_iii" (func $emscripten_asm_const_iii (param i32 i32 i32) (result i32)))
  (table $0 159609 funcref)
  (elem (i32.const 1) $fimport$0 $emscripten_asm_const_iii)
- (global $global$0 (mut i32) (i32.const 16384))
+ (global $global$0 (mut i32) (i32.const 1024))
  (global $global$1 i32 (i32.const 1048))
  (export "__data_end" (global $global$1))
  (export "stackSave" (func $stackSave))