[NFC] Remove getDefaultCallingConvention IsBuiltin (#145904)

ASTContext::getDefaultCallingConvention() was documented as returning
"the default calling convention for the current target", but did not do
this, and was never intended to do this, it has always been controlled
by command-line options to deviate from the target default.

This commit changes ASTContext::getDefaultCallingConvention() to reflect
the fact that it returns the context's default calling convention, not
the target's default calling convention. The IsBuiltin parameter, which
was used to return the target's default calling convention rather than
the context's, is removed in favor of
getTargetInfo().getDefaultCallingConv() which is more explicit of the
intent.

Author: hvdijk

clang/include/clang/AST/ASTContext.h

@@ -2916,10 +2916,14 @@ class ASTContext : public RefCountedBase<ASTContext> {
   NestedNameSpecifier *
   getCanonicalNestedNameSpecifier(NestedNameSpecifier *NNS) const;
 
-  /// Retrieves the default calling convention for the current target.
+  /// Retrieves the default calling convention for the current context.
+  ///
+  /// The context's default calling convention may differ from the current
+  /// target's default calling convention if the -fdefault-calling-conv option
+  /// is used; to get the target's default calling convention, e.g. for built-in
+  /// functions, call getTargetInfo().getDefaultCallingConv() instead.
   CallingConv getDefaultCallingConvention(bool IsVariadic,
-                                          bool IsCXXMethod,
-                                          bool IsBuiltin = false) const;
+                                          bool IsCXXMethod) const;
 
   /// Retrieves the "canonical" template name that refers to a
   /// given template.

clang/include/clang/Basic/TargetInfo.h

@@ -1698,8 +1698,11 @@ class TargetInfo : public TransferrableTargetInfo,
   /// Controls if __arithmetic_fence is supported in the targeted backend.
   virtual bool checkArithmeticFenceSupported() const { return false; }
 
-  /// Gets the default calling convention for the given target and
-  /// declaration context.
+  /// Gets the default calling convention for the given target.
+  ///
+  /// This function does not take into account any user options to override the
+  /// default calling convention. For that, see
+  /// ASTContext::getDefaultCallingConvention().
   virtual CallingConv getDefaultCallingConv() const {
     // Not all targets will specify an explicit calling convention that we can
     // express.  This will always do the right thing, even though it's not

clang/lib/AST/ASTContext.cpp

@@ -12678,10 +12678,9 @@ QualType ASTContext::GetBuiltinType(unsigned Id,
 
   bool Variadic = (TypeStr[0] == '.');
 
-  FunctionType::ExtInfo EI(getDefaultCallingConvention(
-      Variadic, /*IsCXXMethod=*/false, /*IsBuiltin=*/true));
-  if (BuiltinInfo.isNoReturn(Id)) EI = EI.withNoReturn(true);
-
+  FunctionType::ExtInfo EI(Target->getDefaultCallingConv());
+  if (BuiltinInfo.isNoReturn(Id))
+    EI = EI.withNoReturn(true);
 
   // We really shouldn't be making a no-proto type here.
   if (ArgTypes.empty() && Variadic && !getLangOpts().requiresStrictPrototypes())
@@ -13065,43 +13064,38 @@ void ASTContext::forEachMultiversionedFunctionVersion(
 }
 
 CallingConv ASTContext::getDefaultCallingConvention(bool IsVariadic,
-                                                    bool IsCXXMethod,
-                                                    bool IsBuiltin) const {
+                                                    bool IsCXXMethod) const {
   // Pass through to the C++ ABI object
   if (IsCXXMethod)
     return ABI->getDefaultMethodCallConv(IsVariadic);
 
-  // Builtins ignore user-specified default calling convention and remain the
-  // Target's default calling convention.
-  if (!IsBuiltin) {
-    switch (LangOpts.getDefaultCallingConv()) {
-    case LangOptions::DCC_None:
-      break;
-    case LangOptions::DCC_CDecl:
-      return CC_C;
-    case LangOptions::DCC_FastCall:
-      if (getTargetInfo().hasFeature("sse2") && !IsVariadic)
-        return CC_X86FastCall;
-      break;
-    case LangOptions::DCC_StdCall:
-      if (!IsVariadic)
-        return CC_X86StdCall;
-      break;
-    case LangOptions::DCC_VectorCall:
-      // __vectorcall cannot be applied to variadic functions.
-      if (!IsVariadic)
-        return CC_X86VectorCall;
-      break;
-    case LangOptions::DCC_RegCall:
-      // __regcall cannot be applied to variadic functions.
-      if (!IsVariadic)
-        return CC_X86RegCall;
-      break;
-    case LangOptions::DCC_RtdCall:
-      if (!IsVariadic)
-        return CC_M68kRTD;
-      break;
-    }
+  switch (LangOpts.getDefaultCallingConv()) {
+  case LangOptions::DCC_None:
+    break;
+  case LangOptions::DCC_CDecl:
+    return CC_C;
+  case LangOptions::DCC_FastCall:
+    if (getTargetInfo().hasFeature("sse2") && !IsVariadic)
+      return CC_X86FastCall;
+    break;
+  case LangOptions::DCC_StdCall:
+    if (!IsVariadic)
+      return CC_X86StdCall;
+    break;
+  case LangOptions::DCC_VectorCall:
+    // __vectorcall cannot be applied to variadic functions.
+    if (!IsVariadic)
+      return CC_X86VectorCall;
+    break;
+  case LangOptions::DCC_RegCall:
+    // __regcall cannot be applied to variadic functions.
+    if (!IsVariadic)
+      return CC_X86RegCall;
+    break;
+  case LangOptions::DCC_RtdCall:
+    if (!IsVariadic)
+      return CC_M68kRTD;
+    break;
   }
   return Target->getDefaultCallingConv();
 }

clang/lib/Sema/SemaExprCXX.cpp

@@ -3477,8 +3477,8 @@ void Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
     }
   }
 
-  FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
-      /*IsVariadic=*/false, /*IsCXXMethod=*/false, /*IsBuiltin=*/true));
+  FunctionProtoType::ExtProtoInfo EPI(
+      Context.getTargetInfo().getDefaultCallingConv());
 
   QualType BadAllocType;
   bool HasBadAllocExceptionSpec = Name.isAnyOperatorNew();

clang/lib/Sema/SemaLookup.cpp

@@ -22,6 +22,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/LangOptions.h"
+#include "clang/Basic/TargetInfo.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/ModuleLoader.h"
 #include "clang/Lex/Preprocessor.h"
@@ -777,7 +778,7 @@ static void GetOpenCLBuiltinFctOverloads(
     std::vector<QualType> &FunctionList, SmallVector<QualType, 1> &RetTypes,
     SmallVector<SmallVector<QualType, 1>, 5> &ArgTypes) {
   FunctionProtoType::ExtProtoInfo PI(
-      Context.getDefaultCallingConvention(false, false, true));
+      Context.getTargetInfo().getDefaultCallingConv());
   PI.Variadic = false;
 
   // Do not attempt to create any FunctionTypes if there are no return types,

clang/lib/Sema/SemaRISCV.cpp

@@ -417,7 +417,7 @@ void RISCVIntrinsicManagerImpl::CreateRVVIntrinsicDecl(LookupResult &LR,
     ArgTypes.push_back(RVVType2Qual(Context, Sigs[i]));
 
   FunctionProtoType::ExtProtoInfo PI(
-      Context.getDefaultCallingConvention(false, false, true));
+      Context.getTargetInfo().getDefaultCallingConv());
 
   PI.Variadic = false;