[MS ABI]: Support preserve_none in MS ABI #96487

antangelo · 2024-06-24T13:57:26Z

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

llvmbot · 2024-06-24T13:58:01Z

@llvm/pr-subscribers-clang

Author: None (antangelo)

Changes

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 --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@n@@YVXXZ"
+
+struct __declspec(dllexport) S {
+  S(const S &) = delete;
+  S & operator=(const S &) = delete;
+  void __attribute__((__preserve_none__)) m() { }
+};
+// CHECK-DAG: @"?m@S@@QEAVXXZ"
+
+void f(void (__attribute__((__preserve_none__))())) {}
+// CHECK-DAG: @"?f@@YAXP6VXXZ@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);

llvmbot · 2024-06-24T13:58:01Z

@llvm/pr-subscribers-backend-aarch64

Author: None (antangelo)

Changes

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 --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@n@@YVXXZ"
+
+struct __declspec(dllexport) S {
+  S(const S &) = delete;
+  S & operator=(const S &) = delete;
+  void __attribute__((__preserve_none__)) m() { }
+};
+// CHECK-DAG: @"?m@S@@QEAVXXZ"
+
+void f(void (__attribute__((__preserve_none__))())) {}
+// CHECK-DAG: @"?f@@YAXP6VXXZ@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);

AaronBallman

Generally LGTM, though the changes should come with a release note in clang/docs/ReleaseNotes.rst so users know about the fix.

antangelo · 2024-06-24T22:21:47Z

The preserve_none calling convention is new in clang 19 and hasn't been released yet; do fixes need a release note if they happen within the release cycle a feature is added?

AaronBallman · 2024-06-25T15:56:11Z

The preserve_none calling convention is new in clang 19 and hasn't been released yet; do fixes need a release note if they happen within the release cycle a feature is added?

Nope, no need for a release note in this case; I forgot that this was new for clang 19 rather than in clang 18.

AaronBallman · 2024-06-25T15:56:32Z

Do you need me to land the changes on your behalf?

rnk

Thanks for looking at this, let's make this an error instead of a crash in the future.

rnk · 2024-06-25T16:56:11Z

clang/lib/AST/MicrosoftMangle.cpp

@@ -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';


This is not a good long term solution. I emailed the relevant external Microsoft mailing list for discussing these issues and CC'd some folks to inquire about a better long term solution, but we can continue with this approach for now.

rnk · 2024-06-25T16:57:56Z

clang/lib/AST/MicrosoftMangle.cpp

@@ -2986,6 +2989,9 @@ void MicrosoftCXXNameMangler::mangleCallingConvention(CallingConv CC) {
    case CC_Swift: Out << 'S'; break;


The default case here should be a proper compiler error, not an unreachable, since there's no good way to prevent arbitrary calling conventions from reaching the mangler.

If you search this file, you can find examples of "cannot yet mangle". Please copy that error handling pattern and use it in the default case for this switch to improve handling of cases like this in the future.

…osoftMangle

rnk

Thanks!

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

[MS ABI]: Support preserve_none in MS ABI

1e95098

antangelo requested review from rnk, AaronBallman and weiguozhi June 24, 2024 13:57

llvmbot added clang Clang issues not falling into any other category backend:AArch64 clang:frontend Language frontend issues, e.g. anything involving "Sema" labels Jun 24, 2024

AaronBallman approved these changes Jun 24, 2024

View reviewed changes

rnk reviewed Jun 25, 2024

View reviewed changes

Emit error instead of abort on unsupported calling convention in Micr…

2f08dfb

…osoftMangle

antangelo requested a review from rnk June 26, 2024 05:58

rnk approved these changes Jun 26, 2024

View reviewed changes

antangelo merged commit 5dcf3d5 into llvm:main Jun 26, 2024
7 checks passed

antangelo deleted the preserve-none-win-mangling branch June 26, 2024 22:54

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		@@ -2986,6 +2989,9 @@ void MicrosoftCXXNameMangler::mangleCallingConvention(CallingConv CC) {
		case CC_Swift: Out << 'S'; break;

[MS ABI]: Support preserve_none in MS ABI #96487

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