do not move around loop variable incrementations when the helper is used outside the loop

3 files changed, 33 insertions, 2 deletions

diff --git a/tools/eliminator/asm-eliminator-test-output.js b/tools/eliminator/asm-eliminator-test-output.js
index d530a90c..ab4c13cc 100644
--- a/tools/eliminator/asm-eliminator-test-output.js
+++ b/tools/eliminator/asm-eliminator-test-output.js
@@ -954,4 +954,18 @@ function loopVarWithContinue() {
   }
  }
 }
+function helperExtraUse() {
+ var i = 0, i$looptemp = 0;
+ i = 0;
+ while (1) {
+  i$looptemp = i;
+  i = i + 1;
+  work(i$looptemp);
+  work(i);
+  if (check()) {
+   break;
+  }
+ }
+ return i;
+}
 
diff --git a/tools/eliminator/asm-eliminator-test.js b/tools/eliminator/asm-eliminator-test.js
index 8c469964..7b949c44 100644
--- a/tools/eliminator/asm-eliminator-test.js
+++ b/tools/eliminator/asm-eliminator-test.js
@@ -1208,5 +1208,20 @@ function loopVarWithContinue() {
     }
   }
 }
-// EMSCRIPTEN_GENERATED_FUNCTIONS: ["asm", "__Z11printResultPiS_j", "_segment_holding", "__ZN5identC2EiPKcPci", "_vec2Length", "exc", "label", "confuusion", "tempDouble", "_org_apache_harmony_luni_util_NumberConverter_freeFormat__", "__ZN23b2EdgeAndPolygonContact8EvaluateEP10b2ManifoldRK11b2TransformS4_", "_java_nio_charset_Charset_forNameInternal___java_lang_String", "looop2", "looop3", "looop4", "looop5", "looop6", "looop7", "looop8", "multiloop", "multiloop2", "tempDouble2", "watIf", "select2", "binary", "cute", "selfAssign", "elimOneLoopVar", "elimOneLoopVar2", "elimOneLoopVar3", "elimOneLoopVar4", "elimOneLoopVarStillUsed", "elimOneLoopVarStillUsedSE", "elimOneLoopVar5"]
+function helperExtraUse() {
+ var i = 0, inc = 0;
+ i = 0;
+ while (1) {
+  inc = i + 1;
+  work(i);
+  work(inc);
+  if (check()) {
+   break;
+  } else {
+   i = inc;
+  }
+ }
+ return inc;
+}
+// EMSCRIPTEN_GENERATED_FUNCTIONS: ["asm", "__Z11printResultPiS_j", "_segment_holding", "__ZN5identC2EiPKcPci", "_vec2Length", "exc", "label", "confuusion", "tempDouble", "_org_apache_harmony_luni_util_NumberConverter_freeFormat__", "__ZN23b2EdgeAndPolygonContact8EvaluateEP10b2ManifoldRK11b2TransformS4_", "_java_nio_charset_Charset_forNameInternal___java_lang_String", "looop2", "looop3", "looop4", "looop5", "looop6", "looop7", "looop8", "multiloop", "multiloop2", "tempDouble2", "watIf", "select2", "binary", "cute", "selfAssign", "elimOneLoopVar", "elimOneLoopVar2", "elimOneLoopVar3", "elimOneLoopVar4", "elimOneLoopVarStillUsed", "elimOneLoopVarStillUsedSE", "elimOneLoopVar5", "helperExtraUse"]
 
diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index c0096df4..0cd27aa8 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -3704,9 +3704,11 @@ function eliminate(ast, memSafe) {
               }
               if (firstLooperUsage >= 0) {
                 // the looper is used, we cannot simply merge the two variables
-                if ((firstHelperUsage < 0 || firstHelperUsage > lastLooperUsage) && lastLooperUsage+1 < stats.length && triviallySafeToMove(stats[found], asmData)) {
+                if ((firstHelperUsage < 0 || firstHelperUsage > lastLooperUsage) && lastLooperUsage+1 < stats.length && triviallySafeToMove(stats[found], asmData) &&
+                    seenUses[helper] === namings[helper]) {
                   // the helper is not used, or it is used after the last use of the looper, so they do not overlap,
                   // and the last looper usage is not on the last line (where we could not append after it), and the
+                  // helper is not used outside of the loop.
                   // just move the looper definition to after the looper's last use
                   stats.splice(lastLooperUsage+1, 0, stats[found]);
                   stats.splice(found, 1);