Patch to check for integer overflow. It has been

commented on and approved by Richard Smith.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173377 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 29 insertions, 12 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 0d8f764df5..9af16f3201 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -5183,6 +5183,18 @@ void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
   AnalyzeImplicitConversions(*this, E, CC);
 }
 
+/// Diagnose when expression is an integer constant expression and its evaluation
+/// results in integer overflow
+void Sema::CheckForIntOverflow (Expr *E) {
+  if (const BinaryOperator *BExpr = dyn_cast<BinaryOperator>(E->IgnoreParens())) {
+    unsigned Opc = BExpr->getOpcode();
+    if (Opc != BO_Add && Opc != BO_Sub && Opc != BO_Mul)
+      return;
+    llvm::SmallVector<PartialDiagnosticAt, 4> Diags;
+    E->EvaluateForOverflow(Context, &Diags);
+  }
+}
+
 namespace {
 /// \brief Visitor for expressions which looks for unsequenced operations on the
 /// same object.
@@ -5622,9 +5634,12 @@ void Sema::CheckUnsequencedOperations(Expr *E) {
   }
 }
 
-void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc) {
+void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
+                              bool IsConstexpr) {
   CheckImplicitConversions(E, CheckLoc);
   CheckUnsequencedOperations(E);
+  if (!IsConstexpr && !E->isValueDependent())
+    CheckForIntOverflow(E);
 }
 
 void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index ca9610b7d7..538434db00 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7045,7 +7045,9 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
   //   struct T { S a, b; } t = { Temp(), Temp() }
   //
   // we should destroy the first Temp before constructing the second.
-  ExprResult Result = ActOnFinishFullExpr(Init, VDecl->getLocation());
+  ExprResult Result = ActOnFinishFullExpr(Init, VDecl->getLocation(),
+                                          false,
+                                          VDecl->isConstexpr());
   if (Result.isInvalid()) {
     VDecl->setInvalidDecl();
     return;
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 2658a3a2ce..c70041ba51 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -5469,7 +5469,8 @@ ExprResult Sema::IgnoredValueConversions(Expr *E) {
 }
 
 ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
-                                     bool DiscardedValue) {
+                                     bool DiscardedValue,
+                                     bool IsConstexpr) {
   ExprResult FullExpr = Owned(FE);
 
   if (!FullExpr.get())
@@ -5497,7 +5498,7 @@ ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
       return ExprError();
   }
 
-  CheckCompletedExpr(FullExpr.get(), CC);
+  CheckCompletedExpr(FullExpr.get(), CC, IsConstexpr);
   return MaybeCreateExprWithCleanups(FullExpr);
 }
 
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index a2daa18d45..fd3ee0d9f5 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -338,6 +338,12 @@ Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
       // Recover from an error by just forgetting about it.
     }
   }
+  
+  LHSVal = ActOnFinishFullExpr(LHSVal, LHSVal->getExprLoc(), false,
+                               getLangOpts().CPlusPlus11).take();
+  if (RHSVal)
+    RHSVal = ActOnFinishFullExpr(RHSVal, RHSVal->getExprLoc(), false,
+                                 getLangOpts().CPlusPlus11).take();
 
   CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
                                         ColonLoc);
@@ -732,14 +738,7 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
       } else {
         // We already verified that the expression has a i-c-e value (C99
         // 6.8.4.2p3) - get that value now.
-        SmallVector<PartialDiagnosticAt, 8> Diags;
-        LoVal = Lo->EvaluateKnownConstInt(Context, &Diags);
-        if (Diags.size() == 1 && 
-            Diags[0].second.getDiagID() == diag::note_constexpr_overflow) {
-          Diag(Lo->getLocStart(), diag::warn_case_constant_overflow) <<
-            LoVal.toString(10);
-          Diag(Diags[0].first, Diags[0].second);
-        }
+        LoVal = Lo->EvaluateKnownConstInt(Context);
 
         // If the LHS is not the same type as the condition, insert an implicit
         // cast.