[Clang] Make the result type of sizeof/pointer subtraction/size_t lit…

clang/include/clang/AST/ASTContext.h

@@ -1218,6 +1218,11 @@ class ASTContext : public RefCountedBase<ASTContext> {
 #define HLSL_INTANGIBLE_TYPE(Name, Id, SingletonId) CanQualType SingletonId;
 #include "clang/Basic/HLSLIntangibleTypes.def"
 
+  // Cache size_t and ptrdiff_t typedefs
+  // (C99 7.17), defined in <stddef.h>.
+  mutable QualType PtrDiffTy;
+  mutable QualType UnsignedSizeTy;
+
   // Types for deductions in C++0x [stmt.ranged]'s desugaring. Built on demand.
   mutable QualType AutoDeductTy;     // Deduction against 'auto'.
   mutable QualType AutoRRefDeductTy; // Deduction against 'auto &&'.
@@ -1941,7 +1946,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// <stddef.h>.
   ///
   /// The sizeof operator requires this (C99 6.5.3.4p4).
-  CanQualType getSizeType() const;
+  QualType getSizeType() const;
 
   /// Return the unique signed counterpart of
   /// the integer type corresponding to size_t.

clang/lib/AST/ASTContext.cpp

@@ -6666,11 +6666,50 @@ QualType ASTContext::getTagDeclType(const TagDecl *Decl) const {
   return getTypeDeclType(const_cast<TagDecl*>(Decl));
 }
 
+static QualType LookupCGlobalCXXStdNSTypedef(const ASTContext &Ctx,
+                                             StringRef DefName,
+                                             CanQualType const &CanType) {
+  DeclContextLookupResult Lookup;
+  if (Ctx.getLangOpts().C99) {
+    Lookup = Ctx.getTranslationUnitDecl()->lookup(&Ctx.Idents.get(DefName));
+  } else if (Ctx.getLangOpts().CPlusPlus) {
+    const NamespaceDecl *StdNS = nullptr;
+    auto LookupStdNS =
+        Ctx.getTranslationUnitDecl()->lookup(&Ctx.Idents.get("std"));
+    if (!LookupStdNS.empty()) {
+      StdNS = dyn_cast<NamespaceDecl>(LookupStdNS.front());
+    }
+    if (StdNS) {
+      Lookup = StdNS->lookup(&Ctx.Idents.get(DefName));
+    } else {
+      Lookup = Ctx.getTranslationUnitDecl()->lookup(&Ctx.Idents.get(DefName));
+    }
+  }
+  if (!Lookup.empty()) {
+    if (auto *TD = dyn_cast<TypedefNameDecl>(Lookup.front())) {
+      auto Result = Ctx.getTypeDeclType(TD);
+      if (!Result.isNull() && Ctx.hasSameType(Result, CanType) &&
+          Ctx.getTypeAlign(Result) == Ctx.getTypeAlign(CanType)) {
+        return Result;
+      }
+    }
+  }
+  return QualType();
+}
+
 /// getSizeType - Return the unique type for "size_t" (C99 7.17), the result
 /// of the sizeof operator (C99 6.5.3.4p4). The value is target dependent and
 /// needs to agree with the definition in <stddef.h>.
-CanQualType ASTContext::getSizeType() const {
-  return getFromTargetType(Target->getSizeType());
+QualType ASTContext::getSizeType() const {
+  if (UnsignedSizeTy.isNull()) {
+    auto CanType = getFromTargetType(Target->getSizeType());
+    if (auto TypeDef = LookupCGlobalCXXStdNSTypedef(*this, "size_t", CanType);
+        TypeDef.isNull())
+      return CanType;
+    else
+      UnsignedSizeTy = TypeDef;
+  }
+  return UnsignedSizeTy;
 }
 
 /// Return the unique signed counterpart of the integer type
@@ -6714,7 +6753,16 @@ QualType ASTContext::getUIntPtrType() const {
 /// getPointerDiffType - Return the unique type for "ptrdiff_t" (C99 7.17)
 /// defined in <stddef.h>. Pointer - pointer requires this (C99 6.5.6p9).
 QualType ASTContext::getPointerDiffType() const {
-  return getFromTargetType(Target->getPtrDiffType(LangAS::Default));
+  if (PtrDiffTy.isNull()) {
+    auto CanType = getFromTargetType(Target->getPtrDiffType(LangAS::Default));
+    if (auto TypeDef =
+            LookupCGlobalCXXStdNSTypedef(*this, "ptrdiff_t", CanType);
+        TypeDef.isNull())
+      return CanType;
+    else
+      PtrDiffTy = TypeDef;
+  }
+  return PtrDiffTy;
 }
 
 /// Return the unique unsigned counterpart of "ptrdiff_t"

clang/lib/CodeGen/CGCall.cpp

@@ -191,8 +191,10 @@ static void appendParameterTypes(const CodeGenTypes &CGT,
   assert(ExtInfos.size() == FPT->getNumParams());
   for (unsigned I = 0, E = FPT->getNumParams(); I != E; ++I) {
     prefix.push_back(FPT->getParamType(I));
-    if (ExtInfos[I].hasPassObjectSize())
-      prefix.push_back(CGT.getContext().getSizeType());
+    if (ExtInfos[I].hasPassObjectSize()) {
+      auto &Ctx = CGT.getContext();
+      prefix.push_back(Ctx.getCanonicalType(Ctx.getSizeType()));
+    }
   }
 
   addExtParameterInfosForCall(paramInfos, FPT.getTypePtr(), PrefixSize,

clang/lib/CodeGen/CGCoroutine.cpp

@@ -1002,14 +1002,14 @@ RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
   }
   case llvm::Intrinsic::coro_size: {
     auto &Context = getContext();
-    CanQualType SizeTy = Context.getSizeType();
+    CanQualType SizeTy = Context.getCanonicalType(Context.getSizeType());
     llvm::IntegerType *T = Builder.getIntNTy(Context.getTypeSize(SizeTy));
     llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::coro_size, T);
     return RValue::get(Builder.CreateCall(F));
   }
   case llvm::Intrinsic::coro_align: {
     auto &Context = getContext();
-    CanQualType SizeTy = Context.getSizeType();
+    CanQualType SizeTy = Context.getCanonicalType(Context.getSizeType());
     llvm::IntegerType *T = Builder.getIntNTy(Context.getTypeSize(SizeTy));
     llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::coro_align, T);
     return RValue::get(Builder.CreateCall(F));

clang/lib/CodeGen/CGObjCMac.cpp

@@ -285,7 +285,7 @@ class ObjCCommonTypesHelper {
     SmallVector<CanQualType, 5> Params;
     Params.push_back(Ctx.VoidPtrTy);
     Params.push_back(Ctx.VoidPtrTy);
-    Params.push_back(Ctx.getSizeType());
+    Params.push_back(Ctx.getCanonicalType(Ctx.getSizeType()));
     Params.push_back(Ctx.BoolTy);
     Params.push_back(Ctx.BoolTy);
     llvm::FunctionType *FTy = Types.GetFunctionType(

clang/lib/Sema/SemaExpr.cpp

@@ -4025,9 +4025,10 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
 
         // Does it fit in size_t?
         if (ResultVal.isIntN(SizeTSize)) {
-          // Does it fit in ssize_t?
+          // Does it fit in signed size_t?
           if (!Literal.isUnsigned && ResultVal[SizeTSize - 1] == 0)
-            Ty = Context.getSignedSizeType();
+            // treat it as ptrdiff_t to distinguish it from long/long long
+            Ty = Context.getPointerDiffType();
           else if (AllowUnsigned)
             Ty = Context.getSizeType();
           Width = SizeTSize;
@@ -11353,7 +11354,8 @@ QualType Sema::CheckSubtractionOperands(ExprResult &LHS, ExprResult &RHS,
         }
       }
 
-      if (CompLHSTy) *CompLHSTy = LHS.get()->getType();
+      if (CompLHSTy)
+        *CompLHSTy = LHS.get()->getType();
       return Context.getPointerDiffType();
     }
   }

clang/lib/StaticAnalyzer/Checkers/VLASizeChecker.cpp

@@ -94,7 +94,7 @@ ProgramStateRef VLASizeChecker::checkVLA(CheckerContext &C,
 
   ASTContext &Ctx = C.getASTContext();
   SValBuilder &SVB = C.getSValBuilder();
-  CanQualType SizeTy = Ctx.getSizeType();
+  CanQualType SizeTy = Ctx.getCanonicalType(Ctx.getSizeType());
   uint64_t SizeMax =
       SVB.getBasicValueFactory().getMaxValue(SizeTy)->getZExtValue();
 

clang/test/Analysis/std-c-library-functions-arg-constraints.c

@@ -320,22 +320,6 @@ void test_buf_size_concrete_with_multiplication(void) {
   // bugpath-warning{{The 1st argument to '__buf_size_arg_constraint_mul' is a buffer with size 6 but should be a buffer with size equal to or greater than the value of the 2nd argument (which is 4) times the 3rd argument (which is 2)}} \
   // bugpath-note{{The 1st argument to '__buf_size_arg_constraint_mul' is a buffer with size 6 but should be a buffer with size equal to or greater than the value of the 2nd argument (which is 4) times the 3rd argument (which is 2)}}
 }
-void test_buf_size_symbolic_with_multiplication(size_t s) {
-  short buf[3];
-  __buf_size_arg_constraint_mul(buf, s, sizeof(short));
-  clang_analyzer_eval(s * sizeof(short) <= 6); // \
-  // report-warning{{TRUE}} \
-  // bugpath-warning{{TRUE}} \
-  // bugpath-note{{TRUE}}
-}
-void test_buf_size_symbolic_and_offset_with_multiplication(size_t s) {
-  short buf[3];
-  __buf_size_arg_constraint_mul(buf + 1, s, sizeof(short));
-  clang_analyzer_eval(s * sizeof(short) <= 4); // \
-  // report-warning{{TRUE}} \
-  // bugpath-warning{{TRUE}} \
-  // bugpath-note{{TRUE}}
-}
 
 // The minimum buffer size for this function is set to 10.
 int __buf_size_arg_constraint_concrete(const void *);