[clang] [MS ABI]: Support preserve_none in MS ABI (PR #96487)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: None (antangelo)

<details>
<summary>Changes</summary>

Fixes ICE when compiling preserve_nonecc functions on Windows and adds support for the calling convention on AArch64 for Windows targets.

---
Full diff: https://github.com/llvm/llvm-project/pull/96487.diff


4 Files Affected:

- (modified) clang/lib/AST/MicrosoftMangle.cpp (+7-1) 
- (modified) clang/lib/Basic/Targets/AArch64.cpp (+1) 
- (added) clang/test/CodeGenCXX/msabi-preserve-none-cc.cpp (+28) 
- (modified) clang/test/Sema/preserve-none-call-conv.c (+1) 


``````````diff
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 3923d34274703..b49a96f105cfb 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -2962,7 +2962,10 @@ void MicrosoftCXXNameMangler::mangleCallingConvention(CallingConv CC) {
   //                      ::= J # __export __fastcall
   //                      ::= Q # __vectorcall
   //                      ::= S # __attribute__((__swiftcall__)) // Clang-only
-  //                      ::= T # __attribute__((__swiftasynccall__))
+  //                      ::= W # __attribute__((__swiftasynccall__))
+  //                      ::= U # __attribute__((__preserve_most__))
+  //                      ::= V # __attribute__((__preserve_none__)) //
+  //                      Clang-only
   //                            // Clang-only
   //                      ::= w # __regcall
   //                      ::= x # __regcall4
@@ -2986,6 +2989,9 @@ void MicrosoftCXXNameMangler::mangleCallingConvention(CallingConv CC) {
     case CC_Swift: Out << 'S'; break;
     case CC_SwiftAsync: Out << 'W'; break;
     case CC_PreserveMost: Out << 'U'; break;
+    case CC_PreserveNone:
+      Out << 'V';
+      break;
     case CC_X86RegCall:
       if (getASTContext().getLangOpts().RegCall4)
         Out << "x";
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index 31d8121b91d10..2692ddec26ff4 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -1536,6 +1536,7 @@ WindowsARM64TargetInfo::checkCallingConvention(CallingConv CC) const {
   case CC_OpenCLKernel:
   case CC_PreserveMost:
   case CC_PreserveAll:
+  case CC_PreserveNone:
   case CC_Swift:
   case CC_SwiftAsync:
   case CC_Win64:
diff --git a/clang/test/CodeGenCXX/msabi-preserve-none-cc.cpp b/clang/test/CodeGenCXX/msabi-preserve-none-cc.cpp
new file mode 100644
index 0000000000000..29df5e4d84a70
--- /dev/null
+++ b/clang/test/CodeGenCXX/msabi-preserve-none-cc.cpp
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -fdeclspec -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple aarch64-unknown-windows-msvc -fdeclspec -emit-llvm %s -o - | FileCheck %s
+
+void __attribute__((__preserve_none__)) f() {}
+// CHECK-DAG: @"?f@@YVXXZ"
+
+void (__attribute__((__preserve_none__)) *p)();
+// CHECK-DAG: @"?p@@3P6VXXZEA
+
+namespace {
+void __attribute__((__preserve_none__)) __attribute__((__used__)) f() { }
+}
+// CHECK-DAG: @"?f@?A0x{{[^@]*}}@@YVXXZ"
+
+namespace n {
+void __attribute__((__preserve_none__)) f() {}
+}
+// CHECK-DAG: @"?f at n@@YVXXZ"
+
+struct __declspec(dllexport) S {
+  S(const S &) = delete;
+  S & operator=(const S &) = delete;
+  void __attribute__((__preserve_none__)) m() { }
+};
+// CHECK-DAG: @"?m at S@@QEAVXXZ"
+
+void f(void (__attribute__((__preserve_none__))())) {}
+// CHECK-DAG: @"?f@@YAXP6VXXZ at Z"
diff --git a/clang/test/Sema/preserve-none-call-conv.c b/clang/test/Sema/preserve-none-call-conv.c
index 4508095863de5..678fa7d5317e5 100644
--- a/clang/test/Sema/preserve-none-call-conv.c
+++ b/clang/test/Sema/preserve-none-call-conv.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 %s -fsyntax-only -triple x86_64-unknown-unknown -verify
+// RUN: %clang_cc1 %s -fsyntax-only -triple aarch64-unknown-unknown -verify
 
 typedef void typedef_fun_t(int);
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/96487