[clang] Handle CC attrs for UEFI (#138935)

UEFI's default ABI is MS ABI. Handle the calling convention attributes
accordingly.

Author: Prabhuk

clang/lib/Basic/Targets/X86.h

@@ -866,6 +866,7 @@ class LLVM_LIBRARY_VISIBILITY UEFIX86_64TargetInfo
     switch (CC) {
     case CC_C:
     case CC_Win64:
+    case CC_X86_64SysV:
       return CCCR_OK;
     default:
       return CCCR_Warning;

clang/lib/CodeGen/CGCall.cpp

@@ -254,7 +254,7 @@ CodeGenTypes::arrangeFreeFunctionType(CanQual<FunctionProtoType> FTP) {
 }
 
 static CallingConv getCallingConventionForDecl(const ObjCMethodDecl *D,
-                                               bool IsWindows) {
+                                               bool IsTargetDefaultMSABI) {
   // Set the appropriate calling convention for the Function.
   if (D->hasAttr<StdCallAttr>())
     return CC_X86StdCall;
@@ -290,10 +290,10 @@ static CallingConv getCallingConventionForDecl(const ObjCMethodDecl *D,
     return CC_IntelOclBicc;
 
   if (D->hasAttr<MSABIAttr>())
-    return IsWindows ? CC_C : CC_Win64;
+    return IsTargetDefaultMSABI ? CC_C : CC_Win64;
 
   if (D->hasAttr<SysVABIAttr>())
-    return IsWindows ? CC_X86_64SysV : CC_C;
+    return IsTargetDefaultMSABI ? CC_X86_64SysV : CC_C;
 
   if (D->hasAttr<PreserveMostAttr>())
     return CC_PreserveMost;
@@ -581,8 +581,11 @@ CodeGenTypes::arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD,
   }
 
   FunctionType::ExtInfo einfo;
-  bool IsWindows = getContext().getTargetInfo().getTriple().isOSWindows();
-  einfo = einfo.withCallingConv(getCallingConventionForDecl(MD, IsWindows));
+  bool IsTargetDefaultMSABI =
+      getContext().getTargetInfo().getTriple().isOSWindows() ||
+      getContext().getTargetInfo().getTriple().isUEFI();
+  einfo = einfo.withCallingConv(
+      getCallingConventionForDecl(MD, IsTargetDefaultMSABI));
 
   if (getContext().getLangOpts().ObjCAutoRefCount &&
       MD->hasAttr<NSReturnsRetainedAttr>())

clang/lib/Sema/SemaChecking.cpp

@@ -4868,27 +4868,27 @@ static bool checkVAStartABI(Sema &S, unsigned BuiltinID, Expr *Fn) {
   bool IsX64 = TT.getArch() == llvm::Triple::x86_64;
   bool IsAArch64 = (TT.getArch() == llvm::Triple::aarch64 ||
                     TT.getArch() == llvm::Triple::aarch64_32);
-  bool IsWindows = TT.isOSWindows();
+  bool IsWindowsOrUEFI = TT.isOSWindows() || TT.isUEFI();
   bool IsMSVAStart = BuiltinID == Builtin::BI__builtin_ms_va_start;
   if (IsX64 || IsAArch64) {
     CallingConv CC = CC_C;
     if (const FunctionDecl *FD = S.getCurFunctionDecl())
       CC = FD->getType()->castAs<FunctionType>()->getCallConv();
     if (IsMSVAStart) {
       // Don't allow this in System V ABI functions.
-      if (CC == CC_X86_64SysV || (!IsWindows && CC != CC_Win64))
+      if (CC == CC_X86_64SysV || (!IsWindowsOrUEFI && CC != CC_Win64))
         return S.Diag(Fn->getBeginLoc(),
                       diag::err_ms_va_start_used_in_sysv_function);
     } else {
       // On x86-64/AArch64 Unix, don't allow this in Win64 ABI functions.
       // On x64 Windows, don't allow this in System V ABI functions.
       // (Yes, that means there's no corresponding way to support variadic
       // System V ABI functions on Windows.)
-      if ((IsWindows && CC == CC_X86_64SysV) ||
-          (!IsWindows && CC == CC_Win64))
+      if ((IsWindowsOrUEFI && CC == CC_X86_64SysV) ||
+          (!IsWindowsOrUEFI && CC == CC_Win64))
         return S.Diag(Fn->getBeginLoc(),
                       diag::err_va_start_used_in_wrong_abi_function)
-               << !IsWindows;
+               << !IsWindowsOrUEFI;
     }
     return false;
   }

clang/lib/Sema/SemaDeclAttr.cpp

@@ -5397,6 +5397,9 @@ bool Sema::CheckCallingConvAttr(const ParsedAttr &Attrs, CallingConv &CC,
     }
   }
 
+  bool IsTargetDefaultMSABI =
+      Context.getTargetInfo().getTriple().isOSWindows() ||
+      Context.getTargetInfo().getTriple().isUEFI();
   // TODO: diagnose uses of these conventions on the wrong target.
   switch (Attrs.getKind()) {
   case ParsedAttr::AT_CDecl:
@@ -5436,12 +5439,10 @@ bool Sema::CheckCallingConvAttr(const ParsedAttr &Attrs, CallingConv &CC,
     CC = CC_X86RegCall;
     break;
   case ParsedAttr::AT_MSABI:
-    CC = Context.getTargetInfo().getTriple().isOSWindows() ? CC_C :
-                                                             CC_Win64;
+    CC = IsTargetDefaultMSABI ? CC_C : CC_Win64;
     break;
   case ParsedAttr::AT_SysVABI:
-    CC = Context.getTargetInfo().getTriple().isOSWindows() ? CC_X86_64SysV :
-                                                             CC_C;
+    CC = IsTargetDefaultMSABI ? CC_X86_64SysV : CC_C;
     break;
   case ParsedAttr::AT_Pcs: {
     StringRef StrRef;

clang/test/CodeGen/ms_abi.c

@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-freebsd10.0 -emit-llvm < %s | FileCheck -check-prefix=FREEBSD %s
 // RUN: %clang_cc1 -triple x86_64-pc-win32 -emit-llvm < %s | FileCheck -check-prefix=WIN64 %s
+// RUN: %clang_cc1 -triple x86_64-uefi -emit-llvm < %s | FileCheck -check-prefix=WIN64 %s
 
 struct foo {
   int x;

clang/test/CodeGen/sysv_abi.c

@@ -1,7 +1,9 @@
 // RUN: %clang_cc1 -triple x86_64-pc-win32 -emit-llvm  -target-cpu skylake-avx512 < %s | FileCheck %s --check-prefixes=CHECK,AVX
 // RUN: %clang_cc1 -triple x86_64-linux -emit-llvm  -target-cpu skylake-avx512 < %s | FileCheck %s --check-prefixes=CHECK,AVX
+// RUN: %clang_cc1 -triple x86_64-uefi -emit-llvm  -target-cpu skylake-avx512 < %s | FileCheck %s --check-prefixes=CHECK,AVX
 // RUN: %clang_cc1 -triple x86_64-pc-win32 -emit-llvm < %s | FileCheck %s --check-prefixes=CHECK,NOAVX
 // RUN: %clang_cc1 -triple x86_64-linux -emit-llvm < %s | FileCheck %s --check-prefixes=CHECK,NOAVX
+// RUN: %clang_cc1 -triple x86_64-uefi -emit-llvm < %s | FileCheck %s --check-prefixes=CHECK,NOAVX
 
 #define SYSV_CC __attribute__((sysv_abi))
 

clang/test/Sema/callingconv-ms_abi.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -triple x86_64-pc-win32 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -triple x86_64-uefi %s
 
 void __attribute__((ms_abi)) foo(void);
 void (*pfoo)(void) = foo;

clang/test/Sema/varargs-win64.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple x86_64-pc-win32
+// RUN: %clang_cc1 -fsyntax-only -verify %s -triple x86_64-uefi
 
 void __attribute__((sysv_abi)) foo(int a, ...) {
   __builtin_va_list ap;