[cfe-commits] r113580 - in /cfe/trunk: lib/AST/ExprConstant.cpp test/Sema/constant-builtins-2.c

[Douglas Gregor]

Author: dgregor
Date: Fri Sep 10 01:27:15 2010
New Revision: 113580

URL: http://llvm.org/viewvc/llvm-project?rev=113580&view=rev
Log:
Support strlen() and __builtin_strlen() as constant expressions with
the call argument is a string literal. Fixes
<rdar://problem/8413477>.

Modified:
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/test/Sema/constant-builtins-2.c

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=113580&r1=113579&r2=113580&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Fri Sep 10 01:27:15 2010
@@ -1159,6 +1159,24 @@
 
   case Builtin::BI__builtin_expect:
     return Visit(E->getArg(0));
+      
+  case Builtin::BIstrlen:
+  case Builtin::BI__builtin_strlen:
+    // As an extension, we support strlen() and __builtin_strlen() as constant
+    // expressions when the argument is a string literal.
+    if (StringLiteral *S
+               = dyn_cast<StringLiteral>(E->getArg(0)->IgnoreParenImpCasts())) {
+      // The string literal may have embedded null characters. Find the first
+      // one and truncate there.
+      llvm::StringRef Str = S->getString();
+      llvm::StringRef::size_type Pos = Str.find(0);
+      if (Pos != llvm::StringRef::npos)
+        Str = Str.substr(0, Pos);
+      
+      return Success(Str.size(), E);
+    }
+      
+    return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
   }
 }
 

Modified: cfe/trunk/test/Sema/constant-builtins-2.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/constant-builtins-2.c?rev=113580&r1=113579&r2=113580&view=diff
==============================================================================
--- cfe/trunk/test/Sema/constant-builtins-2.c (original)
+++ cfe/trunk/test/Sema/constant-builtins-2.c Fri Sep 10 01:27:15 2010
@@ -50,3 +50,7 @@
 //int h2 = __builtin_expect(0, 0);
 extern long int bi0;
 extern __typeof__(__builtin_expect(0, 0)) bi0;
+
+// Strings
+int array1[__builtin_strlen("ab\0cd")];
+int array2[(sizeof(array1)/sizeof(int)) == 2? 1 : -1];