builtins: make sure that flags is setup properly for __clear_cache

On Linux ARM, the syscall will take 3 arguments (start, end, flags).  Ensure
that we do not pass garbage to the flags, which can cause the cacheflush call to
fail, and therefore cause an abort at runtime.

llvm-svn: 280877

1 files changed, 3 insertions, 1 deletions

diff --git a/compiler-rt/lib/builtins/clear_cache.c b/compiler-rt/lib/builtins/clear_cache.c
index 55bbdd37589..4c2ac3b1eb0 100644
--- a/compiler-rt/lib/builtins/clear_cache.c
+++ b/compiler-rt/lib/builtins/clear_cache.c
@@ -110,10 +110,12 @@ void __clear_cache(void *start, void *end) {
     #elif defined(__linux__)
          register int start_reg __asm("r0") = (int) (intptr_t) start;
          const register int end_reg __asm("r1") = (int) (intptr_t) end;
+         const register int flags __asm("r2") = 0;
          const register int syscall_nr __asm("r7") = __ARM_NR_cacheflush;
          __asm __volatile("svc 0x0"
                           : "=r"(start_reg)
-                          : "r"(syscall_nr), "r"(start_reg), "r"(end_reg));
+                          : "r"(syscall_nr), "r"(start_reg), "r"(end_reg),
+                            "r"(flags));
          if (start_reg != 0) {
              compilerrt_abort();
          }