infer untyped variables in js-optimizer.js by origin variable's type if they are just a copy

3 files changed, 20 insertions, 2 deletions

diff --git a/tools/eliminator/asm-eliminator-test-output.js b/tools/eliminator/asm-eliminator-test-output.js
index e477c320..4cd9cbaa 100644
--- a/tools/eliminator/asm-eliminator-test-output.js
+++ b/tools/eliminator/asm-eliminator-test-output.js
@@ -123,4 +123,10 @@ function switchy() {
     continue;
   }
 }
+function confuusion() {
+  var i = +0, j = +0;
+  func1(+i);
+  j = i;
+  func2(+j);
+}
 
diff --git a/tools/eliminator/asm-eliminator-test.js b/tools/eliminator/asm-eliminator-test.js
index acc07edb..9dc71835 100644
--- a/tools/eliminator/asm-eliminator-test.js
+++ b/tools/eliminator/asm-eliminator-test.js
@@ -156,5 +156,11 @@ function switchy() {
       continue;
   }
 }
-// EMSCRIPTEN_GENERATED_FUNCTIONS: ["asm", "__Z11printResultPiS_j", "_segment_holding", "__ZN5identC2EiPKcPci", "_vec2Length", "exc", "label"]
+function confuusion() {
+  var i = +0;
+  func1(+i);
+  var j = i; // add this var in the middle. should show up with right type later, auto-inferred from i's type
+  func2(+j);
+}
+// EMSCRIPTEN_GENERATED_FUNCTIONS: ["asm", "__Z11printResultPiS_j", "_segment_holding", "__ZN5identC2EiPKcPci", "_vec2Length", "exc", "label", "confuusion"]
 
diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index b82d23d3..3e57c096 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -1392,7 +1392,13 @@ function normalizeAsm(func) {
           var name = v[0];
           var value = v[1];
           if (!(name in data.vars)) {
-            data.vars[name] = detectAsmCoercion(value);
+            if (value[0] != 'name') {
+              data.vars[name] = detectAsmCoercion(value); // detect by coercion
+            } else {
+              var origin = value[1];
+              assert(origin in data.vars);
+              data.vars[name] = data.vars[origin]; // detect by origin variable
+            }
           }
         }
         unVarify(node[1], node);