[clang] 02c06c3 - [CIR][CodeGen][NFC] Share canUseSingleInheritance (#227257)

[via cfe-commits]

Author: Henrich Lauko
Date: 2026-10-08T10:10:45+02:00
New Revision: 02c06c3140efb0822106d26816cbac37e96ffd4b

URL: https://github.com/llvm/llvm-project/commit/02c06c3140efb0822106d26816cbac37e96ffd4b
DIFF: https://github.com/llvm/llvm-project/commit/02c06c3140efb0822106d26816cbac37e96ffd4b.diff

LOG: [CIR][CodeGen][NFC] Share canUseSingleInheritance (#227257)

Deduplicates `canUseSingleInheritance` between CIR and classic CodeGen into
`ItaniumCXXABIUtils.h`.

Assisted-by: Claude Code (Claude Fable 5.1).

Added: 
    

Modified: 
    clang/include/clang/CodeGenUtils/ItaniumCXXABIUtils.h
    clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
    clang/lib/CodeGen/ItaniumCXXABI.cpp
    clang/lib/CodeGenUtils/ItaniumCXXABIUtils.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/CodeGenUtils/ItaniumCXXABIUtils.h b/clang/include/clang/CodeGenUtils/ItaniumCXXABIUtils.h
index 59b94c9bb08c3..9d6a20ef82ab3 100644
--- a/clang/include/clang/CodeGenUtils/ItaniumCXXABIUtils.h
+++ b/clang/include/clang/CodeGenUtils/ItaniumCXXABIUtils.h
@@ -62,6 +62,11 @@ enum BaseClassTypeInfoFlags {
   BCTI_Public = 0x2
 };
 
+/// Return whether the given record decl has a "single, public, non-virtual
+/// base at offset zero (i.e. the derived class is dynamic iff the base is)",
+/// according to Itanium C++ ABI, 2.95p6b.
+bool canUseSingleInheritance(const CXXRecordDecl *RD);
+
 /// Compute the src2dst_offset hint as described in the Itanium C++ ABI [2.9.7].
 CharUnits computeOffsetHint(ASTContext &Ctx, const CXXRecordDecl *Src,
                             const CXXRecordDecl *Dst);

diff  --git a/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp b/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
index 763ed026f8714..25526f0668f00 100644
--- a/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp
@@ -835,32 +835,6 @@ static bool shouldUseExternalRttiDescriptor(CIRGenModule &cgm, QualType ty) {
   return false;
 }
 
-// Return whether the given record decl has a "single,
-// public, non-virtual base at offset zero (i.e. the derived class is dynamic
-// iff the base is)", according to Itanium C++ ABI, 2.95p6b.
-// TODO(cir): this can unified with LLVM codegen
-static bool canUseSingleInheritance(const CXXRecordDecl *rd) {
-  // Check the number of bases.
-  if (rd->getNumBases() != 1)
-    return false;
-
-  // Get the base.
-  CXXRecordDecl::base_class_const_iterator base = rd->bases_begin();
-
-  // Check that the base is not virtual.
-  if (base->isVirtual())
-    return false;
-
-  // Check that the base is public.
-  if (base->getAccessSpecifier() != AS_public)
-    return false;
-
-  // Check that the class is dynamic iff the base is.
-  auto *baseDecl = base->getType()->castAsCXXRecordDecl();
-  return baseDecl->isEmpty() ||
-         baseDecl->isDynamicClass() == rd->isDynamicClass();
-}
-
 const char *vTableClassNameForType(const CIRGenModule &cgm, const Type *ty) {
   // abi::__class_type_info.
   static const char *const classTypeInfo =
@@ -929,7 +903,7 @@ const char *vTableClassNameForType(const CIRGenModule &cgm, const Type *ty) {
       return classTypeInfo;
     }
 
-    if (canUseSingleInheritance(rd)) {
+    if (CodeGenUtils::canUseSingleInheritance(rd)) {
       return siClassTypeInfo;
     }
 
@@ -1425,7 +1399,7 @@ mlir::Attribute CIRGenItaniumRTTIBuilder::buildTypeInfo(
       break;
     }
 
-    if (canUseSingleInheritance(rd)) {
+    if (CodeGenUtils::canUseSingleInheritance(rd)) {
       buildSIClassTypeInfo(loc, rd);
     } else {
       buildVMIClassTypeInfo(loc, rd);

diff  --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 8e9aaa1313528..c851385822291 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3822,34 +3822,6 @@ static bool ShouldUseExternalRTTIDescriptor(CodeGenModule &CGM,
   return false;
 }
 
-// CanUseSingleInheritance - Return whether the given record decl has a "single,
-// public, non-virtual base at offset zero (i.e. the derived class is dynamic
-// iff the base is)", according to Itanium C++ ABI, 2.95p6b.
-static bool CanUseSingleInheritance(const CXXRecordDecl *RD) {
-  // Check the number of bases.
-  if (RD->getNumBases() != 1)
-    return false;
-
-  // Get the base.
-  CXXRecordDecl::base_class_const_iterator Base = RD->bases_begin();
-
-  // Check that the base is not virtual.
-  if (Base->isVirtual())
-    return false;
-
-  // Check that the base is public.
-  if (Base->getAccessSpecifier() != AS_public)
-    return false;
-
-  // Check that the class is dynamic iff the base is.
-  auto *BaseDecl = Base->getType()->castAsCXXRecordDecl();
-  if (!BaseDecl->isEmpty() &&
-      BaseDecl->isDynamicClass() != RD->isDynamicClass())
-    return false;
-
-  return true;
-}
-
 void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty,
                                             llvm::Constant *StorageAddress) {
   // abi::__class_type_info.
@@ -3926,7 +3898,7 @@ void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty,
 
     if (!RD->hasDefinition() || !RD->getNumBases()) {
       VTableName = ClassTypeInfo;
-    } else if (CanUseSingleInheritance(RD)) {
+    } else if (CodeGenUtils::canUseSingleInheritance(RD)) {
       VTableName = SIClassTypeInfo;
     } else {
       VTableName = VMIClassTypeInfo;
@@ -4244,7 +4216,7 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
       break;
     }
 
-    if (CanUseSingleInheritance(RD))
+    if (CodeGenUtils::canUseSingleInheritance(RD))
       BuildSIClassTypeInfo(RD);
     else
       BuildVMIClassTypeInfo(RD);

diff  --git a/clang/lib/CodeGenUtils/ItaniumCXXABIUtils.cpp b/clang/lib/CodeGenUtils/ItaniumCXXABIUtils.cpp
index a1ab26cfc17b0..2f22ab69d4c5a 100644
--- a/clang/lib/CodeGenUtils/ItaniumCXXABIUtils.cpp
+++ b/clang/lib/CodeGenUtils/ItaniumCXXABIUtils.cpp
@@ -61,6 +61,28 @@ CharUnits computeOffsetHint(ASTContext &Ctx, const CXXRecordDecl *Src,
   return Offset;
 }
 
+bool canUseSingleInheritance(const CXXRecordDecl *RD) {
+  // Check the number of bases.
+  if (RD->getNumBases() != 1)
+    return false;
+
+  // Get the base.
+  CXXRecordDecl::base_class_const_iterator Base = RD->bases_begin();
+
+  // Check that the base is not virtual.
+  if (Base->isVirtual())
+    return false;
+
+  // Check that the base is public.
+  if (Base->getAccessSpecifier() != AS_public)
+    return false;
+
+  // Check that the class is dynamic iff the base is.
+  auto *BaseDecl = Base->getType()->castAsCXXRecordDecl();
+  return BaseDecl->isEmpty() ||
+         BaseDecl->isDynamicClass() == RD->isDynamicClass();
+}
+
 namespace {
 /// Contains virtual and non-virtual bases seen when traversing a class
 /// hierarchy.