[cfe-commits] r135359 - in /cfe/trunk: lib/Analysis/UninitializedValues.cpp test/Sema/uninit-variables.c

[Chandler Carruth]

Author: chandlerc
Date: Sat Jul 16 17:27:02 2011
New Revision: 135359

URL: http://llvm.org/viewvc/llvm-project?rev=135359&view=rev
Log:
Revert r135217, which wasn't the correct fix for PR10358. With this
patch, we actually move the state-machine for the value set backwards
one step. This can pretty easily lead to infinite loops where we
continually try to propagate a bit, succeed for one iteration, but then
back up because we find an uninitialized use.

A reduced test case from PR10379 is included.

Modified:
    cfe/trunk/lib/Analysis/UninitializedValues.cpp
    cfe/trunk/test/Sema/uninit-variables.c

Modified: cfe/trunk/lib/Analysis/UninitializedValues.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/UninitializedValues.cpp?rev=135359&r1=135358&r2=135359&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/UninitializedValues.cpp (original)
+++ cfe/trunk/lib/Analysis/UninitializedValues.cpp Sat Jul 16 17:27:02 2011
@@ -495,11 +495,9 @@
 
       ValueVector::reference val = vals[vd];
       if (isUninitialized(val)) {
-        if (bo->getOpcode() != BO_Assign) {
+        if (bo->getOpcode() != BO_Assign)
           reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val));
-          val = Unknown;
-        } else
-          val = Initialized;
+        val = Initialized;
       }
       return;
     }
@@ -528,7 +526,7 @@
         if (isUninitialized(val)) {
           reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val));
           // Don't cascade warnings.
-          val = Unknown;
+          val = Initialized;
         }
         return;
       }
@@ -560,7 +558,7 @@
         if (isUninitialized(val)) {
           reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val));
           // Don't cascade warnings.
-          vals[vd] = Unknown;
+          vals[vd] = Initialized;
         }
       }
       return;

Modified: cfe/trunk/test/Sema/uninit-variables.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/uninit-variables.c?rev=135359&r1=135358&r2=135359&view=diff
==============================================================================
--- cfe/trunk/test/Sema/uninit-variables.c (original)
+++ cfe/trunk/test/Sema/uninit-variables.c Sat Jul 16 17:27:02 2011
@@ -77,7 +77,7 @@
 }
 
 void test12(unsigned n) {
-  for (unsigned i ; n ; ++i) ; // expected-warning{{variable 'i' is uninitialized when used here}} expected-note{{variable 'i' is declared here}} expected-note{{add initialization to silence this warning}}
+  for (unsigned i ; n ; ++i) ; // expected-warning{{variable 'i' may be uninitialized when used here}} expected-note{{variable 'i' is declared here}} expected-note{{add initialization to silence this warning}}
 }
 
 int test13() {
@@ -237,7 +237,7 @@
   void **pc; // expected-note{{variable 'pc' is declared here}} expected-note{{add initialization to silence this warning}}
   void *dummy[] = { &&L1, &&L2 };
  L1:
-    goto *pc; // expected-warning{{variable 'pc' is uninitialized when used here}}
+    goto *pc; // expected-warning{{variable 'pc' may be uninitialized when used here}}
  L2:
     goto *pc;
 }
@@ -289,7 +289,7 @@
 void test43(int i) {
   int x; // expected-note {{variable 'x' is declared here}} expected-note{{add initialization to silence this warning}}
   for (i = 0 ; i < 10; i++)
-    test43_aux(x++); // expected-warning {{variable 'x' is uninitialized when used here}}
+    test43_aux(x++); // expected-warning {{variable 'x' may be uninitialized when used here}}
 }
 
 void test44(int i) {
@@ -297,7 +297,7 @@
   int y; // expected-note {{variable 'y' is declared here}} expected-note{{add initialization to silence this warning}}
   for (i = 0; i < 10; i++ ) {
     test43_aux(x++); // no-warning
-    x += y; // expected-warning {{variable 'y' is uninitialized when used here}}
+    x += y; // expected-warning {{variable 'y' may be uninitialized when used here}}
   }
 }
 
@@ -352,3 +352,18 @@
   }
   return x; // expected-warning {{variable 'x' may be uninitialized when used here}}
 }
+
+// This CFG caused the uninitialized values warning to inf-loop.
+extern int PR10379_g();
+void PR10379_f(int *len) {
+  int new_len; // expected-note {{variable 'new_len' is declared here}} expected-note{{add initialization to silence this warning}}
+  for (int i = 0; i < 42 && PR10379_g() == 0; i++) {
+    if (PR10379_g() == 1)
+      continue;
+    if (PR10379_g() == 2)
+      PR10379_f(&new_len);
+    else if (PR10379_g() == 3)
+      PR10379_f(&new_len);
+    *len += new_len; // expected-warning {{variable 'new_len' may be uninitialized when used here}}
+  }
+}