[llvm] [AArch64] Restrict .variant_pcs directive to ELF targets (PR #140022)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Cullen Rhodes (c-rhodes)

<details>
<summary>Changes</summary>

Directive was implemented in c87bd2d8eb37 to support lazy binding and is emitted for vector PCS functions. It's specific to ELF but is currently emitted for all binary formats and crashing on non-ELF targets.

Fixes #<!-- -->138260

[1] https://github.com/ARM-software/abi-aa/blob/master/aaelf64/aaelf64.rst#st-other-values

---
Full diff: https://github.com/llvm/llvm-project/pull/140022.diff


2 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp (+7-6) 
- (modified) llvm/test/CodeGen/AArch64/variant-pcs.ll (+7) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index a53606851d0a2..f55b7ef7c20bb 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -1344,10 +1344,12 @@ AArch64AsmPrinter::getCodeViewJumpTableInfo(int JTI,
 }
 
 void AArch64AsmPrinter::emitFunctionEntryLabel() {
-  if (MF->getFunction().getCallingConv() == CallingConv::AArch64_VectorCall ||
-      MF->getFunction().getCallingConv() ==
-          CallingConv::AArch64_SVE_VectorCall ||
-      MF->getInfo<AArch64FunctionInfo>()->isSVECC()) {
+  const Triple &TT = TM.getTargetTriple();
+  if (TT.isOSBinFormatELF() &&
+      (MF->getFunction().getCallingConv() == CallingConv::AArch64_VectorCall ||
+       MF->getFunction().getCallingConv() ==
+           CallingConv::AArch64_SVE_VectorCall ||
+       MF->getInfo<AArch64FunctionInfo>()->isSVECC())) {
     auto *TS =
         static_cast<AArch64TargetStreamer *>(OutStreamer->getTargetStreamer());
     TS->emitDirectiveVariantPCS(CurrentFnSym);
@@ -1355,8 +1357,7 @@ void AArch64AsmPrinter::emitFunctionEntryLabel() {
 
   AsmPrinter::emitFunctionEntryLabel();
 
-  if (TM.getTargetTriple().isWindowsArm64EC() &&
-      !MF->getFunction().hasLocalLinkage()) {
+  if (TT.isWindowsArm64EC() && !MF->getFunction().hasLocalLinkage()) {
     // For ARM64EC targets, a function definition's name is mangled differently
     // from the normal symbol, emit required aliases here.
     auto emitFunctionAlias = [&](MCSymbol *Src, MCSymbol *Dst) {
diff --git a/llvm/test/CodeGen/AArch64/variant-pcs.ll b/llvm/test/CodeGen/AArch64/variant-pcs.ll
index 49c504177358e..38510751fdd43 100644
--- a/llvm/test/CodeGen/AArch64/variant-pcs.ll
+++ b/llvm/test/CodeGen/AArch64/variant-pcs.ll
@@ -1,6 +1,13 @@
 ; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sve -o - %s | FileCheck %s --check-prefix=CHECK-ASM --strict-whitespace
+; RUN: llc -mtriple=arm64-apple-macosx -mattr=+sve -o - %s | FileCheck %s --check-prefix=CHECK-ASM-NON-ELF-TARGET
 ; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sve -filetype=obj -o - %s \
 ; RUN:   | llvm-readobj --symbols - | FileCheck %s --check-prefix=CHECK-OBJ
+; RUN: llc -mtriple=arm64-apple-macosx -mattr=+sve -filetype=obj -o - %s \
+; RUN:   | llvm-readobj --symbols - | FileCheck %s --check-prefix=CHECK-OBJ-NON-ELF-TARGET
+
+; .variant_pcs directive should only be emitted for ELF targets.
+; CHECK-ASM-NON-ELF-TARGET-NOT: .variant_pcs
+; CHECK-OBJ-NON-ELF-TARGET-NOT: Other [ (0x80)
 
 define i32 @base_pcs() {
 ; CHECK-ASM-LABEL: base_pcs:

``````````

</details>


https://github.com/llvm/llvm-project/pull/140022