add isInConstantIsland for scanExternalRefs

Author: Jinjie-Huang

bolt/lib/Core/BinaryFunction.cpp

@@ -1699,9 +1699,20 @@ bool BinaryFunction::scanExternalRefs() {
 
       const uint64_t FunctionOffset =
           TargetAddress - TargetFunction->getAddress();
-      BranchTargetSymbol =
-          FunctionOffset ? TargetFunction->addEntryPointAtOffset(FunctionOffset)
-                         : TargetFunction->getSymbol();
+      if (!TargetFunction->isInConstantIsland(TargetAddress)) {
+        BranchTargetSymbol =
+            FunctionOffset
+                ? TargetFunction->addEntryPointAtOffset(FunctionOffset)
+                : TargetFunction->getSymbol();
+      } else {
+        TargetFunction->setIgnored();
+        Success = false;
+        BC.outs() << "BOLT-WARNING: Ignoring entry point at address 0x"
+                  << Twine::utohexstr(Address)
+                  << " in constant island of function " << *TargetFunction
+                  << '\n';
+        break;
+      }
     }
 
     // Can't find more references. Not creating relocations since we are not

bolt/test/AArch64/constant-island-entry.s

@@ -4,6 +4,7 @@
 # RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown %s -o %t.o
 # RUN: %clang %cflags %t.o -pie -Wl,-q -o %t.exe
 # RUN: llvm-bolt %t.exe -o %t.bolt 2>&1 | FileCheck %s
+# RUN: llvm-bolt %t.exe -o %t.bolt -skip-funcs=caller 2>&1 | FileCheck %s
 
 # CHECK: BOLT-WARNING: Ignoring entry point at address 0x{{[0-9a-f]+}} in constant island of function func