[cfe-commits] r138576 - in /cfe/trunk: lib/Analysis/ReachableCode.cpp test/Sema/warn-unreachable.c

[Ted Kremenek]

Author: kremenek
Date: Thu Aug 25 14:28:55 2011
New Revision: 138576

URL: http://llvm.org/viewvc/llvm-project?rev=138576&view=rev
Log:
Teach -Wunreachable-code about dead code caused by macro expansions.  This should suppress false positives resulting from 'assert' and friends.

Modified:
    cfe/trunk/lib/Analysis/ReachableCode.cpp
    cfe/trunk/test/Sema/warn-unreachable.c

Modified: cfe/trunk/lib/Analysis/ReachableCode.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/ReachableCode.cpp?rev=138576&r1=138575&r2=138576&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/ReachableCode.cpp (original)
+++ cfe/trunk/lib/Analysis/ReachableCode.cpp Thu Aug 25 14:28:55 2011
@@ -86,12 +86,10 @@
 }
 
 static bool isValidDeadStmt(const Stmt *S) {
-  SourceLocation Loc = S->getLocStart();
-  if (!(Loc.isValid() && !Loc.isMacroID()))
+  if (S->getLocStart().isInvalid())
     return false;
-  if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
+  if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(S))
     return BO->getOpcode() != BO_Comma;
-  }
   return true;
 }
 
@@ -144,6 +142,12 @@
       }
       continue;
     }
+    
+    // Specially handle macro-expanded code.
+    if (S->getLocStart().isMacroID()) {
+      count += clang::reachable_code::ScanReachableFromBlock(Block, Reachable);
+      continue;
+    }
 
     if (isDeadCodeRoot(Block)) {
       reportDeadCode(S, CB);

Modified: cfe/trunk/test/Sema/warn-unreachable.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-unreachable.c?rev=138576&r1=138575&r2=138576&view=diff
==============================================================================
--- cfe/trunk/test/Sema/warn-unreachable.c (original)
+++ cfe/trunk/test/Sema/warn-unreachable.c Thu Aug 25 14:28:55 2011
@@ -114,3 +114,15 @@
   }  
 }
 
+// Handle unreachable code triggered by macro expansions.
+void __myassert_rtn(const char *, const char *, int, const char *) __attribute__((__noreturn__));
+
+#define myassert(e) \
+    (__builtin_expect(!(e), 0) ? __myassert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
+
+void test_assert() {
+  myassert(0 && "unreachable");
+  return; // no-warning
+}
+
+