[Sanitizers][CFG][arm64e] Fix test because -fsanitize-coverage=control-flow does not sign BB entry

[thetruestblue]

Summary

-fsanitize-coverage=control-flow does not sign entries into basic blocks on arm64e. This test compares a local pointer to a function [signed] with the basic block pointer. Because the entry into the
basic block is unsigned the addresses being compared are signed and unsigned, causing the path never to be taken.
This is a "bandaid" to get this test passing. We strip the signed bits from the pointer to the local functions so that the comparisons pass.
Filed radar: rdar://103042879 to note the behavior.

context: https://github.com/llvm/llvm-project/blob/main/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp#L1068

// blockaddress can not be used on function's entry block.
if (&BB == &F.getEntryBlock())
  CFs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
else
  CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(&BB),
                                                  IntptrPtrTy));

BlockAddress::get is responsible for signing the pointer.

Because of:
https://reviews.llvm.org/D133157

rdar://103042879

[vitalybuka]

compiler-rt/test/sanitizer_common/TestCases/sanitizer_coverage_control_flow.cpp

11–13

59–62

compiler-rt/test/sanitizer_common/TestCases/sanitizer_coverage_control_flow.cpp

 // Tests -fsanitize-coverage=control-flow.
 
 // REQUIRES: has_sancovcc,stable-runtime
 // UNSUPPORTED: i386-darwin, x86_64-darwin
 
 // RUN: %clangxx -O0 -std=c++11 -fsanitize-coverage=control-flow %s -o %t
 // RUN: %run %t 2>&1 | FileCheck %s
 
 #include <cstdint>
 #include <cstdio>
+#if __has_feature(ptrauth_calls)
+  #include <ptrauth.h>
+#else
+  #define ptrauth_strip(__value, __key) (__value)
+#endif
 
 uintptr_t *CFS_BEG, *CFS_END;
 
 extern "C" void __sanitizer_cov_cfs_init(const uintptr_t *cfs_beg,
                                          const uintptr_t *cfs_end) {
   CFS_BEG = (uintptr_t *)cfs_beg;
   CFS_END = (uintptr_t *)cfs_end;
 }
while (*pt) {
       if (*pt == -1 && currBB != main_ptr)
         printf("Indirect call matched.\n");
       pt++;
     }
     pt++;
   }
 }
 
 int main() {
-  auto main_ptr = &main;
-  auto foo_ptr = &foo;
+  auto main_ptr = ptrauth_strip(&main, ptrauth_key_function_pointer);
+  auto foo_ptr = ptrauth_strip(&foo, ptrauth_key_function_pointer);
   int x = 10;
 
   if (x > 0)
     foo(x);
   else
     (*foo_ptr)(x);
 
   check_cfs_section((uintptr_t)(*main_ptr), (uintptr_t)(*foo_ptr));