[cfe-commits] r146842 - in /cfe/trunk: lib/AST/ExprConstant.cpp test/SemaCXX/constant-expression.cpp

[Richard Smith]

Author: rsmith
Date: Sat Dec 17 20:33:09 2011
New Revision: 146842

URL: http://llvm.org/viewvc/llvm-project?rev=146842&view=rev
Log:
PR11604: don't allow floating-literal-to-integer casts in ICEs if the (truncated)
floating literal value does not fit into the destination type. Such casts have
undefined behavior at translation time; treating them as non-ICE matches the
behavior of modern gcc versions.

Modified:
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/test/SemaCXX/constant-expression.cpp

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=146842&r1=146841&r2=146842&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Sat Dec 17 20:33:09 2011
@@ -5252,9 +5252,23 @@
   case Expr::CXXConstCastExprClass:
   case Expr::ObjCBridgedCastExprClass: {
     const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
-    if (isa<ExplicitCastExpr>(E) &&
-        isa<FloatingLiteral>(SubExpr->IgnoreParenImpCasts()))
-      return NoDiag();
+    if (isa<ExplicitCastExpr>(E)) {
+      if (const FloatingLiteral *FL
+            = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
+        unsigned DestWidth = Ctx.getIntWidth(E->getType());
+        bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
+        APSInt IgnoredVal(DestWidth, !DestSigned);
+        bool Ignored;
+        // If the value does not fit in the destination type, the behavior is
+        // undefined, so we are not required to treat it as a constant
+        // expression.
+        if (FL->getValue().convertToInteger(IgnoredVal,
+                                            llvm::APFloat::rmTowardZero,
+                                            &Ignored) & APFloat::opInvalidOp)
+          return ICEDiag(2, E->getLocStart());
+        return NoDiag();
+      }
+    }
     switch (cast<CastExpr>(E)->getCastKind()) {
     case CK_LValueToRValue:
     case CK_NoOp:

Modified: cfe/trunk/test/SemaCXX/constant-expression.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression.cpp?rev=146842&r1=146841&r2=146842&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/constant-expression.cpp (original)
+++ cfe/trunk/test/SemaCXX/constant-expression.cpp Sat Dec 17 20:33:09 2011
@@ -102,3 +102,9 @@
   template<int n> struct S {};
   S<p> s; // expected-error {{not an integral constant expression}}
 }
+
+namespace FloatConvert {
+  typedef int a[(int)42.3];
+  typedef int a[(int)42.997];
+  typedef int b[(int)4e10]; // expected-error {{variable length}}
+}