Merge pull request #26552 from SameerAsal/remove-autolink-section

Remove .swift1_autolink_entries from the final linked binary

Author: compnerd

lib/IRGen/IRGenModule.cpp

@@ -1166,7 +1166,13 @@ void IRGenModule::emitAutolinkInfo() {
     }
     auto EntriesConstant = llvm::ConstantDataArray::getString(
         LLVMContext, EntriesString, /*AddNull=*/false);
-
+    // Mark the swift1_autolink_entries section with the SHF_EXCLUDE attribute
+    // to get the linker to drop it in the final linked binary.
+    // LLVM doesn't provide an interface to specify section attributs in the IR
+    // so we pass the attribute with inline assembly.
+    if (TargetInfo.OutputObjectFormat == llvm::Triple::ELF)
+      Module.appendModuleInlineAsm(".section .swift1_autolink_entries,"
+                                   "\"0x80000000\"");
     auto var =
         new llvm::GlobalVariable(*getModule(), EntriesConstant->getType(), true,
                                  llvm::GlobalValue::PrivateLinkage,

test/IRGen/ELF-remove-autolink-section.swift

@@ -0,0 +1,17 @@
+// RUN: %swiftc_driver -emit-ir %s -o - | %FileCheck %s -check-prefix ELF
+
+// Check that the swift auto link section is available in the object file.
+// RUN: %swiftc_driver -c %s -o %t
+// RUN: llvm-readelf %t -S | %FileCheck %s -check-prefix SECTION
+
+// Checks that the swift auto link section is removed from the final binary.
+// RUN: %swiftc_driver  -emit-executable %s -o %t
+// RUN: llvm-readelf %t -S | %FileCheck %s -check-prefix NOSECTION
+
+// REQUIRES: OS=linux-gnu
+
+print("Hi from Swift!")
+
+// ELF: module asm ".section .swift1_autolink_entries,\220x80000000\22"
+// SECTION: .swift1_autolink_entries
+// NOSECTION-NOT: .swift1_autolink_entries