[X86] Add regcall4 attribute to make a specific function respect regcall ABIv4

[yubingex007-a11y]

TODO: 1. add a testcase in cg side
2. add more testcase in CFE to check such combination {has regcall attr or not , has regcall4 attr or not, has regcall4 option or not}

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 94123d164b910e0e9cca59438a00e619615e5776 83e01839777757e9afbcfdfaa57608bdb162d6f6 -- clang/test/CodeGen/regcall4-attr.c clang/lib/AST/ItaniumMangle.cpp clang/lib/AST/Mangle.cpp clang/lib/AST/TypePrinter.cpp clang/lib/CodeGen/CGCall.cpp clang/lib/CodeGen/CodeGenModule.cpp clang/lib/Sema/SemaDeclAttr.cpp clang/lib/Sema/SemaType.cpp

View the diff from clang-format here.

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 1d456d2b9ddf..f6b504c68ad7 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -524,7 +524,7 @@ private:
   void mangleUnscopedTemplateName(GlobalDecl GD, const DeclContext *DC,
                                   const AbiTagList *AdditionalAbiTags);
   void mangleSourceName(const IdentifierInfo *II);
-  void mangleRegCallName(const IdentifierInfo *II, const FunctionDecl* FD);
+  void mangleRegCallName(const IdentifierInfo *II, const FunctionDecl *FD);
   void mangleDeviceStubName(const IdentifierInfo *II);
   void mangleSourceNameWithAbiTags(
       const NamedDecl *ND, const AbiTagList *AdditionalAbiTags = nullptr);
@@ -1739,7 +1739,8 @@ void CXXNameMangler::mangleUnqualifiedName(
   }
 }
 
-void CXXNameMangler::mangleRegCallName(const IdentifierInfo *II, const FunctionDecl* FD) {
+void CXXNameMangler::mangleRegCallName(const IdentifierInfo *II,
+                                       const FunctionDecl *FD) {
   // <source-name> ::= <positive length number> __regcall3__ <identifier>
   // <number> ::= [n] <non-negative decimal integer>
   // <identifier> ::= <unqualified source code identifier>
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index 6ca95eefe4b0..a4cfd5d168ce 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -1861,7 +1861,9 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
   case attr::MSABI: OS << "ms_abi"; break;
   case attr::SysVABI: OS << "sysv_abi"; break;
   case attr::RegCall: OS << "regcall"; break;
-  case attr::RegCall4: OS << "regcall4"; break;
+  case attr::RegCall4:
+    OS << "regcall4";
+    break;
   case attr::Pcs: {
     OS << "pcs(";
    QualType t = T->getEquivalentType();
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index f29513f6b6e9..c6d3cd89d725 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2316,7 +2316,7 @@ void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
     F->addFnAttrs(B);
     return;
   }
-  
+
   if (D->hasAttr<RegCall4Attr>())
     B.addAttribute("regcall4");
 
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 2c1bfb8d9115..5f829c1141fc 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -9352,7 +9352,7 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
   case ParsedAttr::AT_ThisCall:
   case ParsedAttr::AT_Pascal:
   case ParsedAttr::AT_RegCall:
-  //case ParsedAttr::AT_RegCall4:
+  // case ParsedAttr::AT_RegCall4:
   case ParsedAttr::AT_SwiftCall:
   case ParsedAttr::AT_SwiftAsyncCall:
   case ParsedAttr::AT_VectorCall:
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index d164944c3bde..86d472e33248 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -124,7 +124,7 @@ static void diagnoseBadTypeAttribute(Sema &S, const ParsedAttr &attr,
   case ParsedAttr::AT_StdCall:                                                 \
   case ParsedAttr::AT_ThisCall:                                                \
   case ParsedAttr::AT_RegCall:                                                 \
-  case ParsedAttr::AT_RegCall4:                                                 \
+  case ParsedAttr::AT_RegCall4:                                                \
   case ParsedAttr::AT_Pascal:                                                  \
   case ParsedAttr::AT_SwiftCall:                                               \
   case ParsedAttr::AT_SwiftAsyncCall:                                          \

[yubingex007-a11y]

@mikerice1969 hi, if i uncomment here, and delete L9648-9650, regcall4 won't be added into Decl because hasDeclarator(D) is true:

static void handleCallConvAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
  if (hasDeclarator(D)) return;

do you know why this happened?

[yubingex007-a11y]

there is question here: should we really add a new calling conv CC_X86RegCall4 in CFE?
currently i let regcall4 attr reuse CC_X86RegCall instead of creating CC_X86RegCall4 .

@mikerice1969