[XRay] [compiler-rt] stop writing garbage in naive log records

Summary:
Turns out sizeof(packed) isn't as strong as we'd hoped.  This makes sure
that when we initialize the padding, all 12 bytes will be zero.

Reviewers: dberris, kpw, eizan

Subscribers: delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D42494

llvm-svn: 323755

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler-rt/include/xray/xray_records.h b/compiler-rt/include/xray/xray_records.h
index d4b7b4c31a9..18cc042c6c7 100644
--- a/compiler-rt/include/xray/xray_records.h
+++ b/compiler-rt/include/xray/xray_records.h
@@ -96,7 +96,7 @@ struct alignas(32) XRayRecord {
   uint32_t TId = 0;
 
   // Use some bytes in the end of the record for buffers.
-  char Buffer[4] = {};
+  char Buffer[12] = {};
 } __attribute__((packed));
 
 static_assert(sizeof(XRayRecord) == 32, "XRayRecord != 32 bytes");