Constant expression evaluation refactoring:

 - Remodel Expr::EvaluateAsInt to behave like the other EvaluateAs* functions,
   and add Expr::EvaluateKnownConstInt to capture the current fold-or-assert
   behaviour.
 - Factor out evaluation of bitfield bit widths.
 - Fix a few places which would evaluate an expression twice: once to determine
   whether it is a constant expression, then again to get the value.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141561 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 31 insertions, 45 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 181d40ba01..412ed0ebb5 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -2897,14 +2897,9 @@ IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
     IntRange::forValueOfType(C, E->getType());
   }
 
-  FieldDecl *BitField = E->getBitField();
-  if (BitField) {
-    llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C);
-    unsigned BitWidth = BitWidthAP.getZExtValue();
-
-    return IntRange(BitWidth, 
+  if (FieldDecl *BitField = E->getBitField())
+    return IntRange(BitField->getBitWidthValue(C),
                     BitField->getType()->isUnsignedIntegerOrEnumerationType());
-  }
 
   return IntRange::forValueOfType(C, E->getType());
 }
@@ -3106,16 +3101,14 @@ bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
 
   Expr *OriginalInit = Init->IgnoreParenImpCasts();
 
-  llvm::APSInt Width(32);
   Expr::EvalResult InitValue;
-  if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) ||
-      !OriginalInit->Evaluate(InitValue, S.Context) ||
+  if (!OriginalInit->Evaluate(InitValue, S.Context) ||
       !InitValue.Val.isInt())
     return false;
 
   const llvm::APSInt &Value = InitValue.Val.getInt();
   unsigned OriginalWidth = Value.getBitWidth();
-  unsigned FieldWidth = Width.getZExtValue();
+  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
 
   if (OriginalWidth <= FieldWidth)
     return false;
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 671ba615a8..2ce8a9acae 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -8757,11 +8757,7 @@ void Sema::ActOnLastBitfield(SourceLocation DeclLoc,
   Decl *ivarDecl = AllIvarDecls[AllIvarDecls.size()-1];
   ObjCIvarDecl *Ivar = cast<ObjCIvarDecl>(ivarDecl);
   
-  if (!Ivar->isBitField())
-    return;
-  uint64_t BitFieldSize =
-    Ivar->getBitWidth()->EvaluateAsInt(Context).getZExtValue();
-  if (BitFieldSize == 0)
+  if (!Ivar->isBitField() || Ivar->getBitWidthValue(Context) == 0)
     return;
   ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(CurContext);
   if (!ID) {
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index ea0b06bacb..e9e9d5eb3d 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -2413,9 +2413,8 @@ BuildImplicitMemberInitializer(Sema &SemaRef, CXXConstructorDecl *Constructor,
     QualType ParamType = Param->getType().getNonReferenceType();
 
     // Suppress copying zero-width bitfields.
-    if (const Expr *Width = Field->getBitWidth())
-      if (Width->EvaluateAsInt(SemaRef.Context) == 0)
-        return false;
+    if (Field->isBitField() && Field->getBitWidthValue(SemaRef.Context) == 0)
+      return false;
     
     Expr *MemberExprBase = 
       DeclRefExpr::Create(SemaRef.Context, NestedNameSpecifierLoc(), Param, 
@@ -7975,9 +7974,8 @@ void Sema::DefineImplicitCopyAssignment(SourceLocation CurrentLocation,
     }
 
     // Suppress assigning zero-width bitfields.
-    if (const Expr *Width = Field->getBitWidth())
-      if (Width->EvaluateAsInt(Context) == 0)
-        continue;
+    if (Field->isBitField() && Field->getBitWidthValue(Context) == 0)
+      continue;
     
     QualType FieldType = Field->getType().getNonReferenceType();
     if (FieldType->isIncompleteArrayType()) {
@@ -8396,9 +8394,8 @@ void Sema::DefineImplicitMoveAssignment(SourceLocation CurrentLocation,
     }
 
     // Suppress assigning zero-width bitfields.
-    if (const Expr *Width = Field->getBitWidth())
-      if (Width->EvaluateAsInt(Context) == 0)
-        continue;
+    if (Field->isBitField() && Field->getBitWidthValue(Context) == 0)
+      continue;
     
     QualType FieldType = Field->getType().getNonReferenceType();
     if (FieldType->isIncompleteArrayType()) {
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 21b2622b4a..82b5b17fa4 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -1008,21 +1008,18 @@ void Sema::CheckImplementationIvars(ObjCImplementationDecl *ImpDecl,
     assert (ClsIvar && "missing class ivar");
 
     // First, make sure the types match.
-    if (Context.getCanonicalType(ImplIvar->getType()) !=
-        Context.getCanonicalType(ClsIvar->getType())) {
+    if (!Context.hasSameType(ImplIvar->getType(), ClsIvar->getType())) {
       Diag(ImplIvar->getLocation(), diag::err_conflicting_ivar_type)
         << ImplIvar->getIdentifier()
         << ImplIvar->getType() << ClsIvar->getType();
       Diag(ClsIvar->getLocation(), diag::note_previous_definition);
-    } else if (ImplIvar->isBitField() && ClsIvar->isBitField()) {
-      Expr *ImplBitWidth = ImplIvar->getBitWidth();
-      Expr *ClsBitWidth = ClsIvar->getBitWidth();
-      if (ImplBitWidth->EvaluateAsInt(Context).getZExtValue() !=
-          ClsBitWidth->EvaluateAsInt(Context).getZExtValue()) {
-        Diag(ImplBitWidth->getLocStart(), diag::err_conflicting_ivar_bitwidth)
-          << ImplIvar->getIdentifier();
-        Diag(ClsBitWidth->getLocStart(), diag::note_previous_definition);
-      }
+    } else if (ImplIvar->isBitField() && ClsIvar->isBitField() &&
+               ImplIvar->getBitWidthValue(Context) !=
+               ClsIvar->getBitWidthValue(Context)) {
+      Diag(ImplIvar->getBitWidth()->getLocStart(),
+           diag::err_conflicting_ivar_bitwidth) << ImplIvar->getIdentifier();
+      Diag(ClsIvar->getBitWidth()->getLocStart(),
+           diag::note_previous_definition);
     }
     // Make sure the names are identical.
     if (ImplIvar->getIdentifier() != ClsIvar->getIdentifier()) {
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index ee985f4ba7..34be5db15b 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1405,7 +1405,8 @@ Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                                 D, NameInfo, Ty, VK);
 
   // Just in case we're building an illegal pointer-to-member.
-  if (isa<FieldDecl>(D) && cast<FieldDecl>(D)->getBitWidth())
+  FieldDecl *FD = dyn_cast<FieldDecl>(D);
+  if (FD && FD->isBitField())
     E->setObjectKind(OK_BitField);
 
   return Owned(E);
@@ -8389,7 +8390,7 @@ ExprResult Sema::BuildBuiltinOffsetOf(SourceLocation BuiltinLoc,
     //   (If the specified member is a bit-field, the behavior is undefined.)
     //
     // We diagnose this as an error.
-    if (MemberDecl->getBitWidth()) {
+    if (MemberDecl->isBitField()) {
       Diag(OC.LocEnd, diag::err_offsetof_bitfield)
         << MemberDecl->getDeclName()
         << SourceRange(BuiltinLoc, RParenLoc);
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index e9d4b82c8c..f195d10222 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -1850,15 +1850,15 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
   llvm::APSInt DesignatedStartIndex, DesignatedEndIndex;
   if (D->isArrayDesignator()) {
     IndexExpr = DIE->getArrayIndex(*D);
-    DesignatedStartIndex = IndexExpr->EvaluateAsInt(SemaRef.Context);
+    DesignatedStartIndex = IndexExpr->EvaluateKnownConstInt(SemaRef.Context);
     DesignatedEndIndex = DesignatedStartIndex;
   } else {
     assert(D->isArrayRangeDesignator() && "Need array-range designator");
 
     DesignatedStartIndex =
-      DIE->getArrayRangeStart(*D)->EvaluateAsInt(SemaRef.Context);
+      DIE->getArrayRangeStart(*D)->EvaluateKnownConstInt(SemaRef.Context);
     DesignatedEndIndex =
-      DIE->getArrayRangeEnd(*D)->EvaluateAsInt(SemaRef.Context);
+      DIE->getArrayRangeEnd(*D)->EvaluateKnownConstInt(SemaRef.Context);
     IndexExpr = DIE->getArrayRangeEnd(*D);
 
     // Codegen can't handle evaluating array range designators that have side
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index b30be82cee..7abfdd09de 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -626,7 +626,7 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
         break;
       }
 
-      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
+      llvm::APSInt LoVal = Lo->EvaluateKnownConstInt(Context);
 
       // Convert the value to the same width/sign as the condition.
       ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
@@ -705,7 +705,7 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
         llvm::APSInt &LoVal = CaseRanges[i].first;
         CaseStmt *CR = CaseRanges[i].second;
         Expr *Hi = CR->getRHS();
-        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
+        llvm::APSInt HiVal = Hi->EvaluateKnownConstInt(Context);
 
         // Convert the value to the same width/sign as the condition.
         ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
@@ -845,7 +845,8 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
               << ED->getDeclName();
           }
 
-          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
+          llvm::APSInt Hi = 
+            RI->second->getRHS()->EvaluateKnownConstInt(Context);
           AdjustAPSInt(Hi, CondWidth, CondIsSigned);
           while (EI != EIend && EI->first < Hi)
             EI++;
@@ -873,7 +874,8 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
 
         // Drop unneeded case ranges
         for (; RI != CaseRanges.end(); RI++) {
-          llvm::APSInt Hi = RI->second->getRHS()->EvaluateAsInt(Context);
+          llvm::APSInt Hi =
+            RI->second->getRHS()->EvaluateKnownConstInt(Context);
           AdjustAPSInt(Hi, CondWidth, CondIsSigned);
           if (EI->first <= Hi)
             break;