[llvm] [BOLT] Check entry point address is not in constant island (PR #163418)

[Asher Dobrescu via llvm-commits]

https://github.com/Asher8118 updated https://github.com/llvm/llvm-project/pull/163418

>From 3fe0d0275ac706c48129f40d022f94191297ccc9 Mon Sep 17 00:00:00 2001
From: Ash Dobrescu <ash.dobrescu at arm.com>
Date: Tue, 14 Oct 2025 15:23:02 +0000
Subject: [PATCH 1/2] [BOLT] Check entry point address is not in constant
 island

---
 bolt/lib/Core/BinaryContext.cpp           | 13 +++++++--
 bolt/test/AArch64/constant-island-entry.s | 35 +++++++++++++++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)
 create mode 100644 bolt/test/AArch64/constant-island-entry.s

diff --git a/bolt/lib/Core/BinaryContext.cpp b/bolt/lib/Core/BinaryContext.cpp
index dd0d041692484..c35775464751b 100644
--- a/bolt/lib/Core/BinaryContext.cpp
+++ b/bolt/lib/Core/BinaryContext.cpp
@@ -1336,8 +1336,17 @@ void BinaryContext::processInterproceduralReferences() {
             << Function.getPrintName() << " and "
             << TargetFunction->getPrintName() << '\n';
       }
-      if (uint64_t Offset = Address - TargetFunction->getAddress())
-        TargetFunction->addEntryPointAtOffset(Offset);
+      if (uint64_t Offset = Address - TargetFunction->getAddress()) {
+        if (!TargetFunction->isInConstantIsland(Address)) {
+          TargetFunction->addEntryPointAtOffset(Offset);
+        } else {
+          TargetFunction->setIgnored();
+          this->outs() << "BOLT-WARNING: Ignoring entry point at address 0x"
+                       << Twine::utohexstr(Address)
+                       << " in constant island of function " << *TargetFunction
+                       << '\n';
+        }
+      }
 
       continue;
     }
diff --git a/bolt/test/AArch64/constant-island-entry.s b/bolt/test/AArch64/constant-island-entry.s
new file mode 100644
index 0000000000000..bd0906d87f15f
--- /dev/null
+++ b/bolt/test/AArch64/constant-island-entry.s
@@ -0,0 +1,35 @@
+// This test checks that we ignore functions which add an entry point that
+// is in a costant island.
+
+# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-linux-gnu %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
+
+# CHECK: BOLT-WARNING: Ignoring entry point at address 0x{{[0-9a-f]+}} in constant island of function func
+
+.globl func
+.type func, %function
+func:
+  ret
+  nop
+  b .Lafter_constant
+
+.type constant_island, %object
+constant_island:
+  .xword 0xabcdef
+
+.Lafter_constant:
+  ret
+  .size func, .-func
+
+.globl caller
+.type caller, %function
+caller:
+  bl constant_island
+  ret
+
+.globl main
+.type main, %function
+main:
+  bl caller
+  ret

>From c447ccebec7477723d5bfe363f9a5d763e0a60a0 Mon Sep 17 00:00:00 2001
From: Asher Dobrescu <dobrescuira at yahoo.com>
Date: Tue, 14 Oct 2025 17:07:51 +0100
Subject: [PATCH 2/2] Update constant-island-entry.s

---
 bolt/test/AArch64/constant-island-entry.s | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bolt/test/AArch64/constant-island-entry.s b/bolt/test/AArch64/constant-island-entry.s
index bd0906d87f15f..5b7b906dbf4ea 100644
--- a/bolt/test/AArch64/constant-island-entry.s
+++ b/bolt/test/AArch64/constant-island-entry.s
@@ -1,7 +1,7 @@
 // This test checks that we ignore functions which add an entry point that
 // is in a costant island.
 
-# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-linux-gnu %s -o %t.o
+# 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