[msan] Update origin for the entire destination range on memory store.

Previously we always stored 4 bytes of origin at the destination address
even for 8-byte (and longer) stores.

This should fix rare missing, or incorrect, origin stacks in MSan reports.

llvm-svn: 226658

1 files changed, 21 insertions, 0 deletions

diff --git a/compiler-rt/test/msan/origin-store-long.cc b/compiler-rt/test/msan/origin-store-long.cc
new file mode 100644
index 00000000000..a7c2b7a7d57
--- /dev/null
+++ b/compiler-rt/test/msan/origin-store-long.cc
@@ -0,0 +1,21 @@
+// Check that 8-byte store updates origin for the full store range.
+// RUN: %clangxx_msan -fsanitize-memory-track-origins -m64 -O0 %s -o %t && not %run %t >%t.out 2>&1
+// RUN: FileCheck %s < %t.out && FileCheck %s < %t.out
+// RUN: %clangxx_msan -fsanitize-memory-track-origins -m64 -O2 %s -o %t && not %run %t >%t.out 2>&1
+// RUN: FileCheck %s < %t.out && FileCheck %s < %t.out
+
+#include <sanitizer/msan_interface.h>
+
+int main() {
+  uint64_t *volatile p = new uint64_t;
+  uint64_t *volatile q = new uint64_t;
+  *p = *q;
+  char *z = (char *)p;
+  return z[6];
+// CHECK: WARNING: MemorySanitizer: use-of-uninitialized-value
+// CHECK:   in main {{.*}}origin-store-long.cc:[[@LINE-2]]
+
+// CHECK:  Uninitialized value was created by a heap allocation
+// CHECK:   in main {{.*}}origin-store-long.cc:[[@LINE-8]]
+}
+