From b37279f65ca3bcd34db9cdb3ecab27dcd1bda77b Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Mon, 1 Apr 2019 19:53:46 -0400
Subject: [PATCH] backend/x64/emit_x64_vector: Prevent undefined behavior
 within VectorSignedSaturatedShiftLeft

Avoids undefined behavior by potentially left-shifting a signed negative
value.
---
 src/backend/x64/emit_x64_vector.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/x64/emit_x64_vector.cpp b/src/backend/x64/emit_x64_vector.cpp
index a519cd09..03d47af0 100644
--- a/src/backend/x64/emit_x64_vector.cpp
+++ b/src/backend/x64/emit_x64_vector.cpp
@@ -3838,7 +3838,7 @@ static bool VectorSignedSaturatedShiftLeft(VectorArray<T>& dst, const VectorArra
             dst[i] = saturate(element);
             qc_flag = true;
         } else {
-            const T shifted = element << shift;
+            const T shifted = T(U(element) << shift);
 
             if ((shifted >> shift) != element) {
                 dst[i] = saturate(element);