handle minified function tables

5 files changed, 24 insertions, 18 deletions

diff --git a/src/asm2wasm.cpp b/src/asm2wasm.cpp
index 3e109e010..e20bbe5a1 100644
--- a/src/asm2wasm.cpp
+++ b/src/asm2wasm.cpp
@@ -443,19 +443,6 @@ private:
     }
   }
 
-  // function table null thunks are always named b\d+
-  bool isNullThunk(IString name) {
-    const char *str = name.str;
-    if (*str != 'b') return false;
-    str++;
-    while (1) {
-      if (*str < '0' || *str > '9') return false;
-      str++;
-      if (*str == 0) break;
-    }
-    return true;
-  }
-
   wasm::Arena tempAllocator;
 
   std::map<unsigned, Ref> tempNums;
@@ -586,17 +573,21 @@ void Asm2WasmModule::processAsm(Ref ast) {
           views.emplace(name, View(bytes, integer, signed_));
         } else if (value[0] == ARRAY) {
           // function table. we "merge" them, so e.g.   [foo, b1] , [b2, bar]  =>  [foo, bar] , assuming b* are the aborting thunks
+          // when minified, we can't tell from the name b\d+, but null thunks appear multiple times in a table; others never do
           // TODO: we can drop some b*s at the end of the table
           Ref contents = value[1];
+          std::map<IString, unsigned> counts; // name -> how many times seen
+          for (unsigned k = 0; k < contents->size(); k++) {
+            IString curr = contents[k][1]->getIString();
+            counts[curr]++;
+          }
           for (unsigned k = 0; k < contents->size(); k++) {
             IString curr = contents[k][1]->getIString();
             if (table.vars.size() <= k) {
               table.vars.push_back(curr);
             } else {
-              if (isNullThunk(table.vars[k])) {
+              if (counts[curr] == 1) { // if just one appearance, not a null thunk
                 table.vars[k] = curr;
-              } else {
-                assert(isNullThunk(curr) && "cannot have aliasing function pointers");
               }
             }
           }
diff --git a/test/emcc_O2_hello_world.wast b/test/emcc_O2_hello_world.wast
index 20b476bb3..1b3ff0336 100644
--- a/test/emcc_O2_hello_world.wast
+++ b/test/emcc_O2_hello_world.wast
@@ -21,7 +21,7 @@
   (export "dynCall_ii" $dynCall_ii)
   (export "dynCall_iiii" $dynCall_iiii)
   (export "dynCall_vi" $dynCall_vi)
-  (table $b2 $___stdio_close $___stdout_write $___stdio_seek $_cleanup_418 $___stdio_write $b2 $b2)
+  (table $b0 $___stdio_close $___stdout_write $___stdio_seek $_cleanup_418 $___stdio_write $b1 $b1)
   (func $_malloc (param $i1 i32) (result i32)
     (local $i2 i32)
     (local $i3 i32)
diff --git a/test/emcc_hello_world.wast b/test/emcc_hello_world.wast
index 2705da73e..21394f768 100644
--- a/test/emcc_hello_world.wast
+++ b/test/emcc_hello_world.wast
@@ -25,7 +25,7 @@
   (export "dynCall_ii" $dynCall_ii)
   (export "dynCall_iiii" $dynCall_iiii)
   (export "dynCall_vi" $dynCall_vi)
-  (table $b2 $___stdio_close $___stdout_write $___stdio_seek $___stdio_write $_cleanup $b2 $b2)
+  (table $b0 $___stdio_close $___stdout_write $___stdio_seek $___stdio_write $_cleanup $b1 $b1)
   (func $stackAlloc (param $size i32) (result i32)
     (local $ret i32)
     (block $topmost
diff --git a/test/unit.asm.js b/test/unit.asm.js
index 922923ea3..f737a3ddc 100644
--- a/test/unit.asm.js
+++ b/test/unit.asm.js
@@ -14,6 +14,14 @@ function () {
     temp = t + u + (-u) + (-t);
   }
 
+  function z() {
+  }
+  function w() {
+  }
+
+  var FUNCTION_TABLE_a = [ z, big_negative, z, z ];
+  var FUNCTION_TABLE_b = [ w, w, importedDoubles, w ];
+
   return { big_negative: big_negative };
 }
 
diff --git a/test/unit.wast b/test/unit.wast
index 5fecdcad3..346286b18 100644
--- a/test/unit.wast
+++ b/test/unit.wast
@@ -1,6 +1,7 @@
 (module
   (memory 16777216)
   (export "big_negative" $big_negative)
+  (table $z $big_negative $importedDoubles $z)
   (func $big_negative
     (local $temp f64)
     (block
@@ -44,4 +45,10 @@
       )
     )
   )
+  (func $z
+    (nop)
+  )
+  (func $w
+    (nop)
+  )
 )