[clang] [Clang][AArch64] Define __USER_LABEL_PREFIX__ to # for ARM64EC (PR #78913)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-backend-aarch64

Author: Billy Laws (bylaws)

<details>
<summary>Changes</summary>

This is required so that the linker knows that any symbols defined in assembly code are ARM64EC rather than X86_64.

CC: @<!-- -->cjacek 

---
Full diff: https://github.com/llvm/llvm-project/pull/78913.diff


1 Files Affected:

- (modified) clang/lib/Basic/Targets/AArch64.cpp (+6-4) 


``````````diff
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index d47181bfca4fc86..4f57c30279a91fb 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -1462,10 +1462,12 @@ WindowsARM64TargetInfo::WindowsARM64TargetInfo(const llvm::Triple &Triple,
 }
 
 void WindowsARM64TargetInfo::setDataLayout() {
-  resetDataLayout(Triple.isOSBinFormatMachO()
-                      ? "e-m:o-i64:64-i128:128-n32:64-S128"
-                      : "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128",
-                  Triple.isOSBinFormatMachO() ? "_" : "");
+  if (Triple.isOSBinFormatMachO()) {
+    resetDataLayout("e-m:o-i64:64-i128:128-n32:64-S128", "_");
+  } else {
+    resetDataLayout("e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128",
+                    Triple.isWindowsArm64EC() ? "#" : "");
+  }
 }
 
 TargetInfo::BuiltinVaListKind

``````````

</details>


https://github.com/llvm/llvm-project/pull/78913