From aa53a8a5cb8cfadb4b1230c4b4596dec7fcd75ac Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 2 Aug 2020 18:25:09 +0200
Subject: [PATCH] Multiply by two instead of left-shifting one place

fixes GCC ubsan report of "left shift of negative value -2" in the BLAS tests
---
 kernel/x86_64/zdot.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/x86_64/zdot.c b/kernel/x86_64/zdot.c
index 01169e8e6..423a6f23e 100644
--- a/kernel/x86_64/zdot.c
+++ b/kernel/x86_64/zdot.c
@@ -140,8 +140,8 @@ static void zdot_compute (BLASLONG n, FLOAT *x, BLASLONG inc_x, FLOAT *y, BLASLO
 		i=0;
 		ix=0;
 		iy=0;
-		inc_x <<= 1;
-		inc_y <<= 1;
+		inc_x *= 2;
+		inc_y *= 2;
 		while(i < n)
 		{