[CIR][NFC] Backport changes to use QualType::isStorageConstant (#1992)

We had a comment in the code suggesting that
CIRGenModule::isTypeConstant could be shared with OGCG. The code there
was moved into QualType::isConstantStorage quite a while ago, but the
incubator code never got updated to use it. This change does that.

Author: andykaylor

clang/lib/CIR/CodeGen/CIRGenDecl.cpp

@@ -88,11 +88,13 @@ CIRGenFunction::emitAutoVarAlloca(const VarDecl &D,
       // TODO: deal with CGM.getCodeGenOpts().MergeAllConstants
       // TODO: perhaps we don't need this at all at CIR since this can
       // be done as part of lowering down to LLVM.
+      bool NeedsDtor =
+          D.needsDestruction(getContext()) == QualType::DK_cxx_destructor;
       if ((!getContext().getLangOpts().OpenCL ||
            Ty.getAddressSpace() == LangAS::opencl_constant) &&
           (!NRVO && !D.isEscapingByref() &&
-           CGM.isTypeConstant(Ty, /*ExcludeCtor=*/true,
-                              /*ExcludeDtor=*/false))) {
+           Ty.isConstantStorage(getContext(), /*ExcludeCtor=*/true,
+                                !NeedsDtor))) {
         emitStaticVarDecl(D, cir::GlobalLinkageKind::InternalLinkage);
 
         // Signal this condition to later callbacks.
@@ -600,8 +602,9 @@ cir::GlobalOp CIRGenFunction::addInitializerToStaticVarDecl(
   bool NeedsDtor =
       D.needsDestruction(getContext()) == QualType::DK_cxx_destructor;
 
-  GV.setConstant(
-      CGM.isTypeConstant(D.getType(), /*ExcludeCtor=*/true, !NeedsDtor));
+  GV.setConstant(D.getType().isConstantStorage(
+      getContext(), /*ExcludeCtor=*/true, !NeedsDtor));
+
   GV.setInitialValueAttr(Init);
 
   emitter.finalize(GV);

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -2260,7 +2260,8 @@ static Address createReferenceTemporary(CIRGenFunction &CGF,
     QualType Ty = Inner->getType();
     if (CGF.CGM.getCodeGenOpts().MergeAllConstants &&
         (Ty->isArrayType() || Ty->isRecordType()) &&
-        CGF.CGM.isTypeConstant(Ty, /*ExcludeCtor=*/true, /*ExcludeDtor=*/false))
+        Ty.isConstantStorage(CGF.CGM.getASTContext(), /*ExcludeCtor=*/true,
+                             /*ExcludeDtor=*/false))
       assert(0 && "NYI");
 
     // The temporary memory should be created in the same scope as the extending

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -237,21 +237,6 @@ CIRGenModule::CIRGenModule(mlir::MLIRContext &mlirContext,
 
 CIRGenModule::~CIRGenModule() = default;
 
-bool CIRGenModule::isTypeConstant(QualType ty, bool excludeCtor,
-                                  bool excludeDtor) {
-  if (!ty.isConstant(astContext) && !ty->isReferenceType())
-    return false;
-
-  if (astContext.getLangOpts().CPlusPlus) {
-    if (const CXXRecordDecl *record =
-            astContext.getBaseElementType(ty)->getAsCXXRecordDecl())
-      return excludeCtor && !record->hasMutableFields() &&
-             (record->hasTrivialDestructor() || excludeDtor);
-  }
-
-  return true;
-}
-
 /// FIXME: this could likely be a common helper and not necessarily related
 /// with codegen.
 /// Return the best known alignment for an unknown pointer to a
@@ -393,7 +378,8 @@ bool CIRGenModule::MayBeEmittedEagerly(const ValueDecl *global) {
   if (langOpts.OpenMP && langOpts.OpenMPUseTLS &&
       getASTContext().getTargetInfo().isTLSSupported() &&
       isa<VarDecl>(global) &&
-      !global->getType().isConstantStorage(getASTContext(), false, false) &&
+      !global->getType().isConstantStorage(
+          getASTContext(), /*ExcludeCtor=*/false, /*ExcludeDtor=*/false) &&
       !OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(global))
     return false;
 
@@ -1205,7 +1191,8 @@ CIRGenModule::getOrCreateCIRGlobal(StringRef mangledName, mlir::Type ty,
     // FIXME: This code is overly simple and should be merged with other global
     // handling.
     gv.setAlignmentAttr(getSize(astContext.getDeclAlign(d)));
-    gv.setConstant(isTypeConstant(d->getType(), false, false));
+    gv.setConstant(d->getType().isConstantStorage(
+        astContext, /*ExcludeCtor=*/false, /*ExcludeDtor=*/false));
     // TODO(cir): setLinkageForGV(GV, D);
 
     if (d->getTLSKind()) {
@@ -1399,7 +1386,8 @@ void CIRGenModule::emitGlobalVarDefinition(const clang::VarDecl *d,
        // TODO: Update this when we have interface to check constexpr
        // destructor.
        d->needsDestruction(getASTContext()) ||
-       !d->getType().isConstantStorage(getASTContext(), true, true)))
+       !d->getType().isConstantStorage(getASTContext(), /*ExcludeCtor=*/true,
+                                       /*ExcludeDtor=*/true)))
     return;
 
   const VarDecl *initDecl;
@@ -1569,9 +1557,11 @@ void CIRGenModule::emitGlobalVarDefinition(const clang::VarDecl *d,
     emitter->finalize(gv);
 
   // TODO(cir): If it is safe to mark the global 'constant', do so now.
-  gv.setConstant((d->hasAttr<CUDAConstantAttr>() && langOpts.CUDAIsDevice) ||
-                 (!needsGlobalCtor && !needsGlobalDtor &&
-                  isTypeConstant(d->getType(), true, true)));
+  gv.setConstant(
+      (d->hasAttr<CUDAConstantAttr>() && langOpts.CUDAIsDevice) ||
+      (!needsGlobalCtor && !needsGlobalDtor &&
+       d->getType().isConstantStorage(getASTContext(), /*ExcludeCtor=*/true,
+                                      /*ExcludeDtor=*/true)));
 
   // If it is in a read-only section, mark it 'constant'.
   if (const SectionAttr *sa = d->getAttr<SectionAttr>())
@@ -1963,7 +1953,7 @@ CIRGenModule::getAddrOfGlobalTemporary(const MaterializeTemporaryExpr *expr,
         emitter->emitForInitializer(*value, addrSpace, materializedType);
 
     isConstant = materializedType.isConstantStorage(
-        getASTContext(), /*ExcludeCtor*/ value, /*ExcludeDtor*/ false);
+        getASTContext(), /*ExcludeCtor=*/value, /*ExcludeDtor=*/false);
 
     type = mlir::cast<mlir::TypedAttr>(initialValue).getType();
   } else {

clang/lib/CIR/CodeGen/CIRGenModule.h

@@ -535,17 +535,6 @@ class CIRGenModule : public CIRGenTypeCache {
   /// optimization.
   bool HasHiddenLTOVisibility(const CXXRecordDecl *RD);
 
-  /// Determine whether an object of this type can be emitted
-  /// as a constant.
-  ///
-  /// If ExcludeCtor is true, the duration when the object's constructor runs
-  /// will not be considered. The caller will need to verify that the object is
-  /// not written to during its construction.
-  /// FIXME: in LLVM codegen path this is part of CGM, which doesn't seem
-  /// like necessary, since (1) it doesn't use CGM at all and (2) is AST type
-  /// query specific.
-  bool isTypeConstant(clang::QualType Ty, bool ExcludeCtor, bool ExcludeDtor);
-
   /// FIXME: this could likely be a common helper and not necessarily related
   /// with codegen.
   /// Return the best known alignment for an unknown pointer to a