From 81dcfdcf397dd93b03376ea1e17bd7d0d0c7a335 Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 2 Aug 2020 18:29:56 +0200
Subject: [PATCH] Multiply by 2 instead of left-shifting a potentially negative
 number

fixes GCC ubsan warning in the BLAS tests
---
 kernel/x86_64/zgemv_t_4.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/x86_64/zgemv_t_4.c b/kernel/x86_64/zgemv_t_4.c
index 2ab7a671b..6221471f7 100644
--- a/kernel/x86_64/zgemv_t_4.c
+++ b/kernel/x86_64/zgemv_t_4.c
@@ -235,9 +235,9 @@ int CNAME(BLASLONG m, BLASLONG n, BLASLONG dummy1, FLOAT alpha_r, FLOAT alpha_i,
         if ( m < 1 ) return(0);
         if ( n < 1 ) return(0);
 
-        inc_x <<= 1;
-        inc_y <<= 1;
-        lda   <<= 1;
+        inc_x *= 2;
+        inc_y *= 2;
+        lda  <<= 1;
 	lda4    = lda << 2;
 
 	xbuffer = buffer;