[cfe-commits] r39404 - /cfe/cfe/trunk/Lex/PPExpressions.cpp

[clattner at cs.uiuc.edu]

Author: clattner
Date: Wed Jul 11 11:44:01 2007
New Revision: 39404

URL: http://llvm.org/viewvc/llvm-project?rev=39404&view=rev
Log:
Catch overflow of negate.  This allows us to emit:

t.c:2:17: warning: integer overflow in preprocessor expression
#if -(INTMAX_MAX+1)
                ^
t.c:2:5: warning: integer overflow in preprocessor expression
#if -(INTMAX_MAX+1)
    ^

GCC has some seriously confused source locations in this case:
t.c:2:19: warning: integer overflow in preprocessor expression
t.c:2:20: warning: integer overflow in preprocessor expression

column 19/20 are off the end of the line.

Modified:
    cfe/cfe/trunk/Lex/PPExpressions.cpp

Modified: cfe/cfe/trunk/Lex/PPExpressions.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/cfe/trunk/Lex/PPExpressions.cpp?rev=39404&r1=39403&r2=39404&view=diff

==============================================================================
--- cfe/cfe/trunk/Lex/PPExpressions.cpp (original)
+++ cfe/cfe/trunk/Lex/PPExpressions.cpp Wed Jul 11 11:44:01 2007
@@ -261,13 +261,26 @@
     // Unary plus doesn't modify the value.
     PP.LexNonComment(PeekTok);
     return EvaluateValue(Result, PeekTok, DT, ValueLive, PP);
-  case tok::minus:
+  case tok::minus: {
+    SourceLocation Loc = PeekTok.getLocation();
     PP.LexNonComment(PeekTok);
     if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true;
     // C99 6.5.3.3p3: The sign of the result matches the sign of the operand.
     Result = -Result;
+    
+    bool Overflow = false;
+    if (Result.isUnsigned())
+      Overflow = !Result.isPositive();
+    else if (Result.isMinSignedValue())
+      Overflow = true;   // -MININT is the only thing that overflows.
+      
+    // If this operator is live and overflowed, report the issue.
+    if (Overflow && ValueLive)
+      PP.Diag(Loc, diag::warn_pp_expr_overflow);
+    
     DT.State = DefinedTracker::Unknown;
     return false;
+  }
     
   case tok::tilde:
     PP.LexNonComment(PeekTok);