From: Berk Hess <hess@kth.se>
Date: Fri, 22 Aug 2014 10:37:49 +0000 (+0200)
Subject: Initialize unused velocity constraint components
X-Git-Url: http://biod.pnpi.spb.ru/gitweb/?a=commitdiff_plain;h=839b4f6ce0f8544c90ca7cf74b35e0ab12fe9596;p=alexxy%2Fgromacs.git

Initialize unused velocity constraint components

With domain decomposition, velocity components for communicated
atoms could be uninitialized. These components were never used, but
this could lead to valgrind warnings and floating point exceptions.

Fixes #1576.

Change-Id: Ic673680699578ddf62c2d240342138cbc16490c8
---

diff --git a/src/gromacs/mdlib/constr.c b/src/gromacs/mdlib/constr.c
index fa8275083d..b6878e6bd1 100644
--- a/src/gromacs/mdlib/constr.c
+++ b/src/gromacs/mdlib/constr.c
@@ -203,6 +203,18 @@ int n_flexible_constraints(struct gmx_constr *constr)
     return nflexcon;
 }
 
+static void clear_constraint_quantity_nonlocal(gmx_domdec_t *dd, rvec *q)
+{
+    int nonlocal_at_start, nonlocal_at_end, at;
+
+    dd_get_constraint_range(dd, &nonlocal_at_start, &nonlocal_at_end);
+
+    for (at = nonlocal_at_start; at < nonlocal_at_end; at++)
+    {
+        clear_rvec(q[at]);
+    }
+}
+
 void too_many_constraint_warnings(int eConstrAlg, int warncount)
 {
     const char *abort = "- aborting to avoid logfile runaway.\n"
@@ -431,6 +443,15 @@ gmx_bool constrain(FILE *fplog, gmx_bool bLog, gmx_bool bEner,
     if (cr->dd)
     {
         dd_move_x_constraints(cr->dd, box, x, xprime, econq == econqCoord);
+
+        if (v != NULL)
+        {
+            /* We need to initialize the non-local components of v.
+             * We never actually use these values, but we do increment them,
+             * so we should avoid uninitialized variables and overflows.
+             */
+            clear_constraint_quantity_nonlocal(cr->dd, v);
+        }
     }
 
     if (constr->lincsd != NULL)