Emscripten stack simplification (#1870)

This takes advantage of the recent memory simplification in emscripten, where JS static allocation is done at compile time. That means we know the stack's initial location at compile time, and can apply it. This is the binaryen side of that: * asm2wasm support for asm.js globals with an initial value var X = Y; where Y is not 0 (which is what the stack now is). * wasm-emscripten-finalize support for a flag --initial-stack-pointer=X, and remove the old code to import the stack's initial location.
WebAssembly · Jan 16, 2019 · 777d33d · 777d33d
1 parent cbb24eb
commit 777d33d
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Showing 22 changed files with 82 additions and 40 deletions.
diff --git a/auto_update_tests.py b/auto_update_tests.py
@@ -87,7 +87,7 @@ def update_lld_tests():
       if ext != '.out' and not os.path.exists(out_path):
         continue
       cmd = (WASM_EMSCRIPTEN_FINALIZE +
-             [wast_path, '-S', '--global-base=568'] + ext_args)
+             [wast_path, '-S', '--global-base=568', '--initial-stack-pointer=16384'] + ext_args)
       actual = run_command(cmd)
       with open(out_path, 'w') as o:
         o.write(actual)

diff --git a/scripts/test/lld.py b/scripts/test/lld.py
@@ -38,7 +38,7 @@ def test_wasm_emscripten_finalize():
         continue
 
       cmd = (WASM_EMSCRIPTEN_FINALIZE +
-             [wast_path, '-S', '--global-base=568'] + ext_args)
+             [wast_path, '-S', '--global-base=568', '--initial-stack-pointer=16384'] + ext_args)
       actual = run_command(cmd)
 
       if not os.path.exists(expected_file):

diff --git a/src/asm2wasm.h b/src/asm2wasm.h
@@ -426,13 +426,16 @@ class Asm2WasmBuilder {
   std::map<IString, MappedGlobal> mappedGlobals;
 
 private:
-  void allocateGlobal(IString name, Type type) {
+  void allocateGlobal(IString name, Type type, Literal value=Literal()) {
     assert(mappedGlobals.find(name) == mappedGlobals.end());
+    if (value.type == none) {
+      value = Literal::makeZero(type);
+    }
     mappedGlobals.emplace(name, MappedGlobal(type));
     wasm.addGlobal(builder.makeGlobal(
       name,
       type,
-      LiteralUtils::makeZero(type, wasm),
+      builder.makeConst(value),
       Builder::Mutable
     ));
   }
@@ -986,8 +989,7 @@ void Asm2WasmBuilder::processAsm(Ref ast) {
         Ref value = pair[1];
         if (value->isNumber()) {
           // global int
-          assert(value->getNumber() == 0);
-          allocateGlobal(name, Type::i32);
+          allocateGlobal(name, Type::i32, Literal(int32_t(value->getInteger())));
         } else if (value[0] == BINARY) {
           // int import
           assert(value[1] == OR && value[3]->isNumber() && value[3]->getNumber() == 0);

diff --git a/src/tools/wasm-emscripten-finalize.cpp b/src/tools/wasm-emscripten-finalize.cpp
@@ -36,6 +36,8 @@ using namespace cashew;
 using namespace wasm;
 
 int main(int argc, const char *argv[]) {
+  const uint64_t INVALID_BASE = -1;
+
   std::string infile;
   std::string outfile;
   std::string inputSourceMapFilename;
@@ -46,7 +48,8 @@ int main(int argc, const char *argv[]) {
   bool debugInfo = false;
   bool legalizeJavaScriptFFI = true;
   unsigned numReservedFunctionPointers = 0;
-  uint64_t globalBase;
+  uint64_t globalBase = INVALID_BASE;
+  uint64_t initialStackPointer = INVALID_BASE;
   Options options("wasm-emscripten-finalize",
                   "Performs Emscripten-specific transforms on .wasm files");
   options
@@ -75,11 +78,16 @@ int main(int argc, const char *argv[]) {
                                           const std::string &argument) {
              numReservedFunctionPointers = std::stoi(argument);
            })
-      .add("--global-base", "", "Where lld started to place globals",
+      .add("--global-base", "", "The address at which static globals were placed",
            Options::Arguments::One,
            [&globalBase](Options*, const std::string&argument ) {
              globalBase = std::stoull(argument);
            })
+      .add("--initial-stack-pointer", "", "The initial location of the stack pointer",
+           Options::Arguments::One,
+           [&initialStackPointer](Options*, const std::string&argument ) {
+             initialStackPointer = std::stoull(argument);
+           })
 
       .add("--input-source-map", "-ism", "Consume source map from the specified file",
            Options::Arguments::One,
@@ -141,6 +149,12 @@ int main(int argc, const char *argv[]) {
   uint32_t dataSize = 0;
 
   if (!isSideModule) {
+    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";
@@ -189,7 +203,7 @@ int main(int argc, const char *argv[]) {
   } else {
     generator.generateRuntimeFunctions();
     generator.generateMemoryGrowthFunction();
-    generator.generateStackInitialization();
+    generator.generateStackInitialization(initialStackPointer);
     // 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")) {

diff --git a/src/wasm-emscripten.h b/src/wasm-emscripten.h
@@ -36,7 +36,7 @@ class EmscriptenGlueGenerator {
 
   void generateRuntimeFunctions();
   Function* generateMemoryGrowthFunction();
-  void generateStackInitialization();
+  void generateStackInitialization(Address addr);
 
   // Create thunks for use with emscripten Runtime.dynCall. Creates one for each
   // signature in the indirect function table.

diff --git a/src/wasm/wasm-emscripten.cpp b/src/wasm/wasm-emscripten.cpp
@@ -156,19 +156,9 @@ 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);
+void EmscriptenGlueGenerator::generateStackInitialization(Address addr) {
   auto* stackPointer = getStackPointerGlobal();
-  assert(stackPointer->init->is<Const>());
-  stackPointer->init = builder.makeGetGlobal(import->name, i32);
+  stackPointer->init->cast<Const>()->value = Literal(int32_t(addr));
 }
 
 static bool hasI64ResultOrParam(FunctionType* ft) {

diff --git a/test/lld/duplicate_imports.wast.out b/test/lld/duplicate_imports.wast.out
@@ -9,15 +9,14 @@
  (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 funcref)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

diff --git a/test/lld/em_asm.wast.out b/test/lld/em_asm.wast.out
@@ -7,14 +7,13 @@
  (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 funcref)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66192))
  (global $global$2 i32 (i32.const 652))
  (export "memory" (memory $0))

diff --git a/test/lld/em_asm_table.wast.out b/test/lld/em_asm_table.wast.out
@@ -4,12 +4,11 @@
  (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 funcref)
  (elem (i32.const 1) $fimport$0 $emscripten_asm_const_iii)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 1048))
  (export "__data_end" (global $global$1))
  (export "stackSave" (func $stackSave))

diff --git a/test/lld/hello_world.wast.mem.out b/test/lld/hello_world.wast.mem.out
@@ -3,11 +3,10 @@
  (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 funcref)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

diff --git a/test/lld/hello_world.wast.out b/test/lld/hello_world.wast.out
@@ -3,12 +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)
  (data (i32.const 568) "Hello, world\00")
  (table $0 1 1 funcref)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 581))
  (export "memory" (memory $0))

diff --git a/test/lld/init.wast.out b/test/lld/init.wast.out
@@ -1,11 +1,10 @@
 (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 funcref)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66112))
  (global $global$2 i32 (i32.const 576))
  (export "memory" (memory $0))

diff --git a/test/lld/recursive.wast.out b/test/lld/recursive.wast.out
@@ -3,12 +3,11 @@
  (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 funcref)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66128))
  (global $global$2 i32 (i32.const 587))
  (export "memory" (memory $0))

diff --git a/test/lld/reserved_func_ptr.wast.jscall.out b/test/lld/reserved_func_ptr.wast.jscall.out
@@ -18,7 +18,6 @@
  (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)))
@@ -29,7 +28,7 @@
  (memory $0 2)
  (table $0 21 21 funcref)
  (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) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66112))
  (global $global$2 i32 (i32.const 568))
  (export "memory" (memory $0))

diff --git a/test/lld/reserved_func_ptr.wast.out b/test/lld/reserved_func_ptr.wast.out
@@ -8,12 +8,11 @@
  (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 funcref)
  (elem (i32.const 1) $_Z18address_taken_funciii $_Z19address_taken_func2iii)
- (global $global$0 (mut i32) (global.get $stack$init))
+ (global $global$0 (mut i32) (i32.const 16384))
  (global $global$1 i32 (i32.const 66112))
  (global $global$2 i32 (i32.const 568))
  (export "memory" (memory $0))

diff --git a/test/unit.asm.js b/test/unit.asm.js
@@ -30,6 +30,8 @@ function asm(global, env, buffer) {
   var HEAPF32 = new global.Float32Array(buffer);
   var HEAPF64 = new global.Float64Array(buffer);
 
+  var nonZero = 1337;
+
   function big_negative() {
     var temp = 0.0;
     temp = +-2147483648;
@@ -785,6 +787,7 @@ function asm(global, env, buffer) {
     emterpretify_assertions_safeHeap();
     call_emscripten_log();
     mod_detectSign(1.0, 2.31, 9.78);
+    nonZero = nonZero + 1 | 0;
   }
 
   function v() {

diff --git a/test/unit.fromasm b/test/unit.fromasm
@@ -26,6 +26,7 @@
  (global $Int (mut i32) (i32.const 0))
  (global $Double (mut f64) (f64.const 0))
  (global $n (mut i32) (global.get $n$asm2wasm$import))
+ (global $nonZero (mut i32) (i32.const 1337))
  (global $exportedNumber i32 (i32.const 42))
  (export "big_negative" (func $big_negative))
  (export "pick" (func $big_negative))
@@ -1162,6 +1163,12 @@
     )
    )
   )
+  (global.set $nonZero
+   (i32.add
+    (global.get $nonZero)
+    (i32.const 1)
+   )
+  )
  )
  (func $vi (; 55 ;) (; has Stack IR ;) (param $0 i32)
   (nop)

diff --git a/test/unit.fromasm.clamp b/test/unit.fromasm.clamp
@@ -24,6 +24,7 @@
  (global $Int (mut i32) (i32.const 0))
  (global $Double (mut f64) (f64.const 0))
  (global $n (mut i32) (global.get $n$asm2wasm$import))
+ (global $nonZero (mut i32) (i32.const 1337))
  (global $exportedNumber i32 (i32.const 42))
  (export "big_negative" (func $big_negative))
  (export "pick" (func $big_negative))
@@ -1238,6 +1239,12 @@
     )
    )
   )
+  (global.set $nonZero
+   (i32.add
+    (global.get $nonZero)
+    (i32.const 1)
+   )
+  )
  )
  (func $vi (; 57 ;) (; has Stack IR ;) (param $0 i32)
   (nop)

diff --git a/test/unit.fromasm.clamp.no-opts b/test/unit.fromasm.clamp.no-opts
@@ -31,6 +31,7 @@
  (global $tempDoublePtr (mut i32) (global.get $tempDoublePtr$asm2wasm$import))
  (global $n (mut i32) (global.get $n$asm2wasm$import))
  (global $STACKTOP (mut i32) (global.get $STACKTOP$asm2wasm$import))
+ (global $nonZero (mut i32) (i32.const 1337))
  (global $exportedNumber i32 (i32.const 42))
  (export "big_negative" (func $big_negative))
  (export "pick" (func $exportMe))
@@ -2215,6 +2216,12 @@
     (f64.const 9.78)
    )
   )
+  (global.set $nonZero
+   (i32.add
+    (global.get $nonZero)
+    (i32.const 1)
+   )
+  )
  )
  (func $v (; 83 ;)
   (nop)

diff --git a/test/unit.fromasm.imprecise b/test/unit.fromasm.imprecise
@@ -22,6 +22,7 @@
  (global $Int (mut i32) (i32.const 0))
  (global $Double (mut f64) (f64.const 0))
  (global $n (mut i32) (global.get $n$asm2wasm$import))
+ (global $nonZero (mut i32) (i32.const 1337))
  (global $exportedNumber i32 (i32.const 42))
  (export "big_negative" (func $big_negative))
  (export "pick" (func $big_negative))
@@ -1141,6 +1142,12 @@
     (f64.const 1)
    )
   )
+  (global.set $nonZero
+   (i32.add
+    (global.get $nonZero)
+    (i32.const 1)
+   )
+  )
  )
  (func $vi (; 54 ;) (; has Stack IR ;) (param $0 i32)
   (nop)

diff --git a/test/unit.fromasm.imprecise.no-opts b/test/unit.fromasm.imprecise.no-opts
@@ -31,6 +31,7 @@
  (global $tempDoublePtr (mut i32) (global.get $tempDoublePtr$asm2wasm$import))
  (global $n (mut i32) (global.get $n$asm2wasm$import))
  (global $STACKTOP (mut i32) (global.get $STACKTOP$asm2wasm$import))
+ (global $nonZero (mut i32) (i32.const 1337))
  (global $exportedNumber i32 (i32.const 42))
  (export "big_negative" (func $big_negative))
  (export "pick" (func $exportMe))
@@ -2100,6 +2101,12 @@
     (f64.const 9.78)
    )
   )
+  (global.set $nonZero
+   (i32.add
+    (global.get $nonZero)
+    (i32.const 1)
+   )
+  )
  )
  (func $v (; 78 ;)
   (nop)