From 40d67da7caaef4c23399306cbcac7883a925ce6f Mon Sep 17 00:00:00 2001
From: Marc Hoersken <info@marc-hoersken.de>
Date: Sat, 12 Sep 2020 21:59:26 +0200
Subject: [PATCH] multi: reuse WinSock events variable in Curl_multi_wait

Since the struct is quite large (1 long and 10 ints) we
declare it once at the beginning of the function instead
of multiple times inside loops to avoid stack movements.

Reviewed-by: Viktor Szakats
Reviewed-by: Daniel Stenberg

Closes #5886
---
 lib/multi.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/lib/multi.c b/lib/multi.c
index b9316b3c4..f374b2721 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -1095,6 +1095,7 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
   bool ufds_malloc = FALSE;
 #else
   struct pollfd pre_poll;
+  WSANETWORKEVENTS wsa_events;
   DEBUGASSERT(multi->wsa_event != WSA_INVALID_EVENT);
 #endif
 
@@ -1295,18 +1296,17 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
       for(i = 0; i < extra_nfds; i++) {
         unsigned short mask = 0;
 #ifdef USE_WINSOCK
-        WSANETWORKEVENTS events = {0};
+        wsa_events.lNetworkEvents = 0;
         mask = extra_fds[i].revents;
         if(WSAEnumNetworkEvents(extra_fds[i].fd, multi->wsa_event,
-                                &events) == 0) {
-          if(events.lNetworkEvents & (FD_READ|FD_ACCEPT|FD_CLOSE))
+                                &wsa_events) == 0) {
+          if(wsa_events.lNetworkEvents & (FD_READ|FD_ACCEPT|FD_CLOSE))
             mask |= CURL_WAIT_POLLIN;
-          if(events.lNetworkEvents & (FD_WRITE|FD_CONNECT|FD_CLOSE))
+          if(wsa_events.lNetworkEvents & (FD_WRITE|FD_CONNECT|FD_CLOSE))
             mask |= CURL_WAIT_POLLOUT;
-          if(events.lNetworkEvents & FD_OOB)
+          if(wsa_events.lNetworkEvents & FD_OOB)
             mask |= CURL_WAIT_POLLPRI;
-
-          if(ret && events.lNetworkEvents != 0)
+          if(ret && wsa_events.lNetworkEvents != 0)
             retcode++;
         }
         WSAEventSelect(extra_fds[i].fd, multi->wsa_event, 0);
@@ -1320,7 +1320,6 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
         if(r & POLLPRI)
           mask |= CURL_WAIT_POLLPRI;
 #endif
-
         extra_fds[i].revents = mask;
       }
 
@@ -1334,13 +1333,13 @@ static CURLMcode Curl_multi_wait(struct Curl_multi *multi,
 
           for(i = 0; i < MAX_SOCKSPEREASYHANDLE; i++) {
             if(bitmap & (GETSOCK_READSOCK(i) | GETSOCK_WRITESOCK(i))) {
-              WSANETWORKEVENTS events = {0};
+              wsa_events.lNetworkEvents = 0;
               if(WSAEnumNetworkEvents(sockbunch[i], multi->wsa_event,
-                                      &events) == 0) {
-                if(ret && events.lNetworkEvents != 0)
+                                      &wsa_events) == 0) {
+                if(ret && wsa_events.lNetworkEvents != 0)
                   retcode++;
               }
-              if(ret && !timeout_ms && !events.lNetworkEvents) {
+              if(ret && !timeout_ms && wsa_events.lNetworkEvents == 0) {
                 if((bitmap & GETSOCK_READSOCK(i)) &&
                    SOCKET_READABLE(sockbunch[i], 0) > 0)
                   retcode++;