ctor-eval fixes (#996)

* fix wasm-ctor-eval, we need to look for the STACKTOP etc. imports, they may not be named, if this build is not with -g

* pack memory after ctor evalling, since we merge it up which is less efficient

* do some useful opts after ctor-evalling, to clean things up

1 files changed, 19 insertions, 3 deletions

diff --git a/src/tools/wasm-ctor-eval.cpp b/src/tools/wasm-ctor-eval.cpp
index 160e4a4f2..67c9f9707 100644
--- a/src/tools/wasm-ctor-eval.cpp
+++ b/src/tools/wasm-ctor-eval.cpp
@@ -32,6 +32,7 @@
 #include "wasm-interpreter.h"
 #include "wasm-builder.h"
 #include "ast/memory-utils.h"
+#include "ast/global-utils.h"
 
 using namespace wasm;
 
@@ -153,10 +154,14 @@ public:
     // prepare scratch memory
     stack.resize(STACK_SIZE);
     // fill usable values for stack imports
-    auto total = STACK_START + STACK_SIZE;
-    globals["STACKTOP"] = Literal(int32_t(STACK_START));
-    globals["STACK_MAX"] = Literal(int32_t(STACK_START + STACK_SIZE));
+    if (auto* stackTop = GlobalUtils::getGlobalInitializedToImport(wasm, "env", "STACKTOP")) {
+      globals[stackTop->name] = Literal(int32_t(STACK_START));
+    }
+    if (auto* stackMax = GlobalUtils::getGlobalInitializedToImport(wasm, "env", "STACK_MAX")) {
+      globals[stackMax->name] = Literal(int32_t(STACK_START));
+    }
     // tell the module to accept writes up to the stack end
+    auto total = STACK_START + STACK_SIZE;
     memorySize = total / Memory::kPageSize;
   }
 
@@ -398,6 +403,17 @@ int main(int argc, const char* argv[]) {
   }
   evalCtors(wasm, ctors);
 
+  // Do some useful optimizations after the evalling
+  {
+    PassRunner passRunner(&wasm);
+    passRunner.add("memory-packing"); // we flattened it, so re-optimize
+    passRunner.add("remove-unused-names");
+    passRunner.add("dce");
+    passRunner.add("merge-blocks");
+    passRunner.add("vacuum");
+    passRunner.run();
+  }
+
   if (options.extra.count("output") > 0) {
     if (options.debug) std::cerr << "writing..." << std::endl;
     ModuleWriter writer;