1 // RUN: %clangxx_msan -fsanitize-memory-track-origins=2 -O1 %s -o %t && not %run %t 2>&1 | FileCheck %s
2 
3 // musl does not define FP_XSTATE_MAGIC1.
4 // REQUIRES: x86_64-target-arch && glibc-2.27
5 
6 #include <pthread.h>
7 #include <signal.h>
8 #include <stdint.h>
9 #include <ucontext.h>
10 
11 void handler(int sig, siginfo_t *info, void *uctx) {
12   volatile int uninit;
13   auto *mctx = &static_cast<ucontext_t *>(uctx)->uc_mcontext;
14   auto *fpregs = mctx->fpregs;
15   // The member names differ across header versions, but the actual layout
16   // is always the same.  So avoid using members, just use arithmetic.
17   const uint32_t *after_xmm =
18       reinterpret_cast<const uint32_t *>(fpregs + 1) - 24;
19   if (after_xmm[12] == FP_XSTATE_MAGIC1)
20     reinterpret_cast<_xstate *>(mctx->fpregs)->ymmh.ymmh_space[0] = uninit;
21   else
22     mctx->gregs[REG_RAX] = uninit;
23 }
24 
25 int main(int argc, char **argv) {
26   struct sigaction act = {};
27   act.sa_sigaction = handler;
28   act.sa_flags = SA_SIGINFO;
29   sigfillset(&act.sa_mask);
30   sigaction(SIGPROF, &act, 0);
31   pthread_kill(pthread_self(), SIGPROF);
32   return 0;
33 }
34 
35 // CHECK: WARNING: MemorySanitizer:
36