From b85e8b51464d0ea1d76d08c2a1b53648e9b7ed9c Mon Sep 17 00:00:00 2001
From: Alon Zakai <alonzakai@gmail.com>
Date: Wed, 12 Jul 2017 11:16:04 -0700
Subject: zero shifts are not sign-extends

---
 src/ast/properties.h | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/ast/properties.h b/src/ast/properties.h
index 9121deba5..097f7a8f0 100644
--- a/src/ast/properties.h
+++ b/src/ast/properties.h
@@ -60,11 +60,13 @@ struct Properties {
     if (auto* outer = curr->dynCast<Binary>()) {
       if (outer->op == ShrSInt32) {
         if (auto* outerConst = outer->right->dynCast<Const>()) {
-          if (auto* inner = outer->left->dynCast<Binary>()) {
-            if (inner->op == ShlInt32) {
-              if (auto* innerConst = inner->right->dynCast<Const>()) {
-                if (outerConst->value == innerConst->value) {
-                  return inner->left;
+          if (outerConst->value.geti32() != 0) {
+            if (auto* inner = outer->left->dynCast<Binary>()) {
+              if (inner->op == ShlInt32) {
+                if (auto* innerConst = inner->right->dynCast<Const>()) {
+                  if (outerConst->value == innerConst->value) {
+                    return inner->left;
+                  }
                 }
               }
             }
@@ -87,11 +89,13 @@ struct Properties {
     if (auto* outer = curr->dynCast<Binary>()) {
       if (outer->op == ShrSInt32) {
         if (auto* outerConst = outer->right->dynCast<Const>()) {
-          if (auto* inner = outer->left->dynCast<Binary>()) {
-            if (inner->op == ShlInt32) {
-              if (auto* innerConst = inner->right->dynCast<Const>()) {
-                if (outerConst->value.leU(innerConst->value).geti32()) {
-                  return inner->left;
+          if (outerConst->value.geti32() != 0) {
+            if (auto* inner = outer->left->dynCast<Binary>()) {
+              if (inner->op == ShlInt32) {
+                if (auto* innerConst = inner->right->dynCast<Const>()) {
+                  if (outerConst->value.leU(innerConst->value).geti32()) {
+                    return inner->left;
+                  }
                 }
               }
             }
-- 
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