From 8c564e9b57dc0fb913ce31de99c6ad556ae04fa7 Mon Sep 17 00:00:00 2001
From: Christian Sigg <chsigg@users.noreply.github.com>
Date: Fri, 6 Dec 2019 18:14:55 +0100
Subject: [PATCH] Fix clang build (#271)

Clang doesn't understand `optimize("O0")`. It has `noopt`, which GCC doesn't understand. Wrap the difference in a macro.
---
 src/init.cc | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/init.cc b/src/init.cc
index 1ee2a73..15a9e7c 100644
--- a/src/init.cc
+++ b/src/init.cc
@@ -124,10 +124,18 @@ ncclResult_t ncclGetUniqueId(ncclUniqueId* out) {
 }
 
 // Prevent compiler from optimizing out these operations
-void __attribute__((optimize("O0"))) commPoison(ncclComm_t comm) {
+#ifdef __clang__
+#define NCCL_NO_OPTIMIZE __attribute__((noopt)))
+#else
+#define NCCL_NO_OPTIMIZE __attribute__((optimize("O0")))
+#endif
+
+void NCCL_NO_OPTIMIZE commPoison(ncclComm_t comm) {
   comm->rank = comm->cudaDev = comm->busId = comm->nRanks = -1;
 }
 
+#undef NCCL_NO_OPTIMIZE
+
 static ncclResult_t commFree(ncclComm_t comm) {
   if (comm == NULL)
     return ncclSuccess;