From 7cee63bba3805bd49f0c03b94d65f02dea04f946 Mon Sep 17 00:00:00 2001
From: Bung <crc32@qq.com>
Date: Tue, 25 Aug 2020 15:58:32 +0800
Subject: [PATCH] avoid #8231, bitwise move to mul,div (#15070)

* avoid #8231, bitwise move to mul,div

* add test for #8231

* fix bitwise move when div result is float

* bitwise move depends on typ.size
---
 compiler/jsgen.nim | 12 ++++++++++--
 tests/js/t8231.nim |  3 +++
 2 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 tests/js/t8231.nim

diff --git a/compiler/jsgen.nim b/compiler/jsgen.nim
index ede4d14e0..bea5225e6 100644
--- a/compiler/jsgen.nim
+++ b/compiler/jsgen.nim
@@ -602,8 +602,16 @@ proc arithAux(p: PProc, n: PNode, r: var TCompRes, op: TMagic) =
   of mMulF64: applyFormat("($1 * $2)", "($1 * $2)")
   of mDivF64: applyFormat("($1 / $2)", "($1 / $2)")
   of mShrI: applyFormat("", "")
-  of mShlI: applyFormat("($1 << $2)", "($1 << $2)")
-  of mAshrI: applyFormat("($1 >> $2)", "($1 >> $2)")
+  of mShlI: 
+    if n[1].typ.size <= 4:
+      applyFormat("($1 << $2)", "($1 << $2)")
+    else:
+      applyFormat("($1 * Math.pow(2,$2))", "($1 * Math.pow(2,$2))")
+  of mAshrI: 
+    if n[1].typ.size <= 4:
+      applyFormat("($1 >> $2)", "($1 >> $2)")
+    else:
+      applyFormat("Math.floor($1 / Math.pow(2,$2))", "Math.floor($1 / Math.pow(2,$2))")
   of mBitandI: applyFormat("($1 & $2)", "($1 & $2)")
   of mBitorI: applyFormat("($1 | $2)", "($1 | $2)")
   of mBitxorI: applyFormat("($1 ^ $2)", "($1 ^ $2)")
diff --git a/tests/js/t8231.nim b/tests/js/t8231.nim
new file mode 100644
index 000000000..b0625a621
--- /dev/null
+++ b/tests/js/t8231.nim
@@ -0,0 +1,3 @@
+import strutils
+
+doAssert formatSize(2462056448, '.', bpIEC, false) == "2.293GiB"
\ No newline at end of file