Add feature flags and validation to wasm-metadce (#2364)

Sometimes wasm-metadce is the last tool to run over a binary in
Emscripten, and in that case it needs to know what features are
enabled in order to emit a valid binary. For example it needs to know
whether to emit a data count section.

Author: tlively

auto_update_tests.py

@@ -305,7 +305,7 @@ def update_metadce_tests():
             print('..', t)
             t = os.path.join(options.binaryen_test, 'metadce', t)
             graph = t + '.graph.txt'
-            cmd = WASM_METADCE + [t, '--graph-file=' + graph, '-o', 'a.wast', '-S']
+            cmd = WASM_METADCE + [t, '--graph-file=' + graph, '-o', 'a.wast', '-S', '-all']
             stdout = run_command(cmd)
             actual = open('a.wast').read()
             out = t + '.dced'

check.py

@@ -264,7 +264,7 @@ def run_wasm_metadce_tests():
             print('..', t)
             t = os.path.join(test_dir, t)
             graph = t + '.graph.txt'
-            cmd = WASM_METADCE + [t, '--graph-file=' + graph, '-o', 'a.wast', '-S']
+            cmd = WASM_METADCE + [t, '--graph-file=' + graph, '-o', 'a.wast', '-S', '-all']
             stdout = run_command(cmd)
             expected = t + '.dced'
             with open('a.wast') as seen:

src/tools/wasm-metadce.cpp

@@ -29,11 +29,12 @@
 #include "ir/module-utils.h"
 #include "pass.h"
 #include "support/colors.h"
-#include "support/command-line.h"
 #include "support/file.h"
 #include "support/json.h"
+#include "tool-options.h"
 #include "wasm-builder.h"
 #include "wasm-io.h"
+#include "wasm-validator.h"
 
 using namespace wasm;
 
@@ -403,7 +404,7 @@ int main(int argc, const char* argv[]) {
   std::string graphFile;
   bool dump = false;
 
-  Options options(
+  ToolOptions options(
     "wasm-metadce",
     "This tool performs dead code elimination (DCE) on a larger space "
     "that the wasm module is just a part of. For example, if you have "
@@ -508,6 +509,15 @@ int main(int argc, const char* argv[]) {
     }
   }
 
+  options.applyFeatures(wasm);
+
+  if (options.passOptions.validate) {
+    if (!WasmValidator().validate(wasm)) {
+      WasmPrinter::printModule(&wasm);
+      Fatal() << "error in validating input";
+    }
+  }
+
   auto graphInput(
     read_file<std::string>(graphFile, Flags::Text, Flags::Release));
   auto* copy = strdup(graphInput.c_str());

test/metadce/all-outside.wast

@@ -1,2 +1 @@
 (module)
-

test/metadce/spanning_cycle.wast

@@ -1,10 +1,18 @@
 (module
+ (memory 1 1)
+ (data passive "Hello, datacount section!")
+
  (import "env" "js_func" (func $a_js_func))
 
  (export "wasm_func_a" (func $a_wasm_func))
 
  (func $a_wasm_func
+  ;; refer to the data segment to keep it around
+  (memory.init 0
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 25)
+  )
   (call $a_js_func)
  )
 )
-

test/metadce/spanning_cycle.wast.dced

@@ -1,8 +1,15 @@
 (module
  (type $FUNCSIG$v (func))
  (import "env" "js_func" (func $a_js_func))
+ (memory $0 1 1)
+ (data passive "Hello, datacount section!")
  (export "wasm_func_a" (func $a_wasm_func))
  (func $a_wasm_func (; 1 ;) (type $FUNCSIG$v)
+  (memory.init 0
+   (i32.const 0)
+   (i32.const 0)
+   (i32.const 25)
+  )
   (call $a_js_func)
  )
 )