[clang][bytecode] Add Descriptor::getDataType() (llvm#132681)

This returns the type of data in the Block, which might be different
than the type of the expression or declaration we created the block for.
This lets us remove some special cases from CheckNewDeleteForms() and
CheckNewTypeMismatch().

Author: tbaederr

clang/lib/AST/ByteCode/Descriptor.cpp

@@ -16,6 +16,7 @@
 #include "PrimType.h"
 #include "Record.h"
 #include "Source.h"
+#include "clang/AST/ExprCXX.h"
 
 using namespace clang;
 using namespace clang::interp;
@@ -453,6 +454,30 @@ QualType Descriptor::getElemQualType() const {
   return T;
 }
 
+QualType Descriptor::getDataType(const ASTContext &Ctx) const {
+  auto MakeArrayType = [&](QualType ElemType) -> QualType {
+    if (IsArray)
+      return Ctx.getConstantArrayType(
+          ElemType, APInt(64, static_cast<uint64_t>(getNumElems()), false),
+          nullptr, ArraySizeModifier::Normal, 0);
+    return ElemType;
+  };
+
+  if (const auto *E = asExpr()) {
+    if (isa<CXXNewExpr>(E))
+      return MakeArrayType(E->getType()->getPointeeType());
+
+    // std::allocator.allocate() call.
+    if (const auto *ME = dyn_cast<CXXMemberCallExpr>(E);
+        ME && ME->getRecordDecl()->getName() == "allocator" &&
+        ME->getMethodDecl()->getName() == "allocate")
+      return MakeArrayType(E->getType()->getPointeeType());
+    return E->getType();
+  }
+
+  return getType();
+}
+
 SourceLocation Descriptor::getLocation() const {
   if (auto *D = dyn_cast<const Decl *>(Source))
     return D->getLocation();

clang/lib/AST/ByteCode/Descriptor.h

@@ -207,6 +207,7 @@ struct Descriptor final {
 
   QualType getType() const;
   QualType getElemQualType() const;
+  QualType getDataType(const ASTContext &Ctx) const;
   SourceLocation getLocation() const;
   SourceInfo getLoc() const;
 

clang/lib/AST/ByteCode/Interp.cpp

@@ -979,17 +979,7 @@ bool CheckNewDeleteForms(InterpState &S, CodePtr OpPC,
   if (AllocForm == DeleteForm)
     return true;
 
-  QualType TypeToDiagnose;
-  // We need to shuffle things around a bit here to get a better diagnostic,
-  // because the expression we allocated the block for was of type int*,
-  // but we want to get the array size right.
-  if (D->isArray()) {
-    QualType ElemQT = D->getType()->getPointeeType();
-    TypeToDiagnose = S.getASTContext().getConstantArrayType(
-        ElemQT, APInt(64, static_cast<uint64_t>(D->getNumElems()), false),
-        nullptr, ArraySizeModifier::Normal, 0);
-  } else
-    TypeToDiagnose = D->getType()->getPointeeType();
+  QualType TypeToDiagnose = D->getDataType(S.getASTContext());
 
   const SourceInfo &E = S.Current->getSource(OpPC);
   S.FFDiag(E, diag::note_constexpr_new_delete_mismatch)
@@ -1665,15 +1655,7 @@ bool CheckNewTypeMismatch(InterpState &S, CodePtr OpPC, const Expr *E,
     return false;
 
   const auto *NewExpr = cast<CXXNewExpr>(E);
-  QualType StorageType = Ptr.getType();
-
-  if ((isa_and_nonnull<CXXNewExpr>(Ptr.getFieldDesc()->asExpr()) ||
-       isa_and_nonnull<CXXMemberCallExpr>(Ptr.getFieldDesc()->asExpr())) &&
-      StorageType->isPointerType()) {
-    // FIXME: Are there other cases where this is a problem?
-    StorageType = StorageType->getPointeeType();
-  }
-
+  QualType StorageType = Ptr.getFieldDesc()->getDataType(S.getASTContext());
   const ASTContext &ASTCtx = S.getASTContext();
   QualType AllocType;
   if (ArraySize) {

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -158,6 +158,8 @@ static QualType getElemType(const Pointer &P) {
     return T->getAs<PointerType>()->getPointeeType();
   if (Desc->isArray())
     return Desc->getElemQualType();
+  if (const auto *AT = T->getAsArrayTypeUnsafe())
+    return AT->getElementType();
   return T;
 }