[msan] Fix truncated stack trace in chained origin reports.

This is a leftover from the times when the next (chained) origin id
was stored as the last frame of a stack trace.

llvm-svn: 211878

compiler-rt/lib/msan/msan_report.cc

@@ -90,7 +90,7 @@ static void DescribeOrigin(u32 id) {
       // FIXME: copied? modified? passed through? observed?
       Printf("  %sUninitialized value was stored to memory at%s\n", d.Origin(),
              d.End());
-      StackTrace::PrintStack(trace, size - 1);
+      StackTrace::PrintStack(trace, size);
       id = prev_id;
     }
   }

compiler-rt/test/msan/chained_origin_empty_stack.cc

@@ -0,0 +1,33 @@
+// RUN: %clangxx_msan -fsanitize-memory-track-origins=2 -m64 -O3 %s -o %t && \
+// RUN:     MSAN_OPTIONS=malloc_context_size=1 not %run %t 2>&1 | FileCheck %s
+
+// Test that stack trace for the intermediate store is not empty.
+
+// CHECK: MemorySanitizer: use-of-uninitialized-value
+// CHECK:   #0 {{.*}} in main
+
+// CHECK: Uninitialized value was stored to memory at
+// CHECK:   #0 {{.*}} in fn_g
+
+// CHECK: Uninitialized value was created by an allocation of 'z' in the stack frame of function 'main'
+// CHECK:   #0 {{.*}} in main
+
+#include <stdio.h>
+
+volatile int x;
+
+__attribute__((noinline))
+void fn_g(int a) {
+  x = a;
+}
+
+__attribute__((noinline))
+void fn_f(int a) {
+  fn_g(a);
+}
+
+int main(int argc, char *argv[]) {
+  int volatile z;
+  fn_f(z);
+  return x;
+}