[sancov][sanitizer-common] Correct sanitizer coverage point

Sanitizer coverage point should be the previous instruction PC of the
caller and the offset to the previous instruction might be different
on each CPU architecture.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D119233

compiler-rt/lib/sanitizer_common/sanitizer_coverage_libcdep_new.cpp

@@ -14,6 +14,7 @@
 #  include "sanitizer_allocator_internal.h"
 #  include "sanitizer_atomic.h"
 #  include "sanitizer_common.h"
+#  include "sanitizer_common/sanitizer_stacktrace.h"
 #  include "sanitizer_file.h"
 #  include "sanitizer_interface_internal.h"
 
@@ -222,7 +223,8 @@ SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_dump_coverage(const uptr* pcs,
 
 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_guard, u32* guard) {
   if (!*guard) return;
-  __sancov::pc_guard_controller.TracePcGuard(guard, GET_CALLER_PC() - 1);
+  __sancov::pc_guard_controller.TracePcGuard(
+      guard, StackTrace::GetPreviousInstructionPc(GET_CALLER_PC()));
 }
 
 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_cov_trace_pc_guard_init,