[clang] In cc1as, re-add call to initSections with NoExecStack parameter (PR #186013)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Jackson Schuster (jtschuster)

<details>
<summary>Changes</summary>

Fixes https://github.com/llvm/llvm-project/issues/186004

913c5b4d1fff removed the `initSections(Opts.NoExecStack, *STI)` call from cc1as_main.cpp, assuming it was redundant with the initSections call inside Parser->Run(). However, Parser->Run() calls initSections(false, ...), it does not forward NoExecStack. This causes -Wa,--noexecstack / -cc1as -mnoexecstack to be parsed but silently ignored, producing objects without .note.GNU-stack.

This breaks linking with ld.bfd >= 2.39, which errors on missing .note.GNU-stack sections by default.

Restore the explicit initSections call with Opts.NoExecStack. Effectively a revert of 913c5b4d1fff.

Add a test to validate the section is present in the output. Existing tests only validated the flag was forwarded from clang.

---
Full diff: https://github.com/llvm/llvm-project/pull/186013.diff


2 Files Affected:

- (added) clang/test/Misc/cc1as-noexecstack.s (+10) 
- (modified) clang/tools/driver/cc1as_main.cpp (+1) 


``````````diff
diff --git a/clang/test/Misc/cc1as-noexecstack.s b/clang/test/Misc/cc1as-noexecstack.s
new file mode 100644
index 0000000000000..91ed33e5a0e04
--- /dev/null
+++ b/clang/test/Misc/cc1as-noexecstack.s
@@ -0,0 +1,10 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang -cc1as -triple x86_64-linux-gnu -filetype obj -mnoexecstack -o %t.o %s
+// RUN: llvm-readelf -S %t.o | FileCheck %s
+
+// CHECK: .note.GNU-stack
+
+.text
+.globl foo
+foo:
+    retq
diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp
index c6cdd46a41f37..944321212a33e 100644
--- a/clang/tools/driver/cc1as_main.cpp
+++ b/clang/tools/driver/cc1as_main.cpp
@@ -602,6 +602,7 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
     Triple T(Opts.Triple);
     Str.reset(TheTarget->createMCObjectStreamer(
         T, Ctx, std::move(MAB), std::move(OW), std::move(CE), *STI));
+    Str->initSections(Opts.NoExecStack, *STI);
     if (T.isOSBinFormatMachO() && T.isOSDarwin()) {
       Triple *TVT = Opts.DarwinTargetVariantTriple
                         ? &*Opts.DarwinTargetVariantTriple

``````````

</details>


https://github.com/llvm/llvm-project/pull/186013