[llvm-branch-commits] [llvm-branch] r89436 - /llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp

[Dan Gohman]

Author: djg
Date: Thu Nov 19 19:48:18 2009
New Revision: 89436

URL: http://llvm.org/viewvc/llvm-project?rev=89436&view=rev
Log:
$ svn merge -c 89411 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r89411 into '.':
U    lib/Analysis/CaptureTracking.cpp
$ svn merge -c 89419 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r89419 into '.':
G    lib/Analysis/CaptureTracking.cpp
$ svn merge -c 89421 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r89421 into '.':
G    lib/Analysis/CaptureTracking.cpp
$ svn merge -c 89434 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r89434 into '.':
G    lib/Analysis/CaptureTracking.cpp

Modified:
    llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp

Modified: llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp?rev=89436&r1=89435&r2=89436&view=diff

==============================================================================
--- llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp (original)
+++ llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp Thu Nov 19 19:48:18 2009
@@ -19,6 +19,7 @@
 #include "llvm/Analysis/CaptureTracking.h"
 #include "llvm/Instructions.h"
 #include "llvm/Value.h"
+#include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/CallSite.h"
@@ -56,8 +57,7 @@
       // Not captured if the callee is readonly, doesn't return a copy through
       // its return value and doesn't unwind (a readonly function can leak bits
       // by throwing an exception or not depending on the input value).
-      if (CS.onlyReadsMemory() && CS.doesNotThrow() &&
-          I->getType() == Type::getVoidTy(V->getContext()))
+      if (CS.onlyReadsMemory() && CS.doesNotThrow() && I->getType()->isVoidTy())
         break;
 
       // Not captured if only passed via 'nocapture' arguments.  Note that
@@ -106,9 +106,21 @@
       }
       break;
     case Instruction::ICmp:
-      // Comparing the pointer against null does not count as a capture.
-      if (isa<ConstantPointerNull>(I->getOperand(1)))
+      // Don't count comparisons of the original value against null as captures.
+      // This allows us to ignore comparisons of malloc results with null,
+      // for example.
+      if (isIdentifiedObject(V))
+        if (ConstantPointerNull *CPN =
+              dyn_cast<ConstantPointerNull>(I->getOperand(1)))
+          if (CPN->getType()->getAddressSpace() == 0)
+            break;
+      // Don't count comparisons of two pointers within the same object
+      // as captures.
+      if (I->getOperand(0)->getUnderlyingObject() ==
+          I->getOperand(1)->getUnderlyingObject())
         break;
+      // Otherwise, be conservative. There are crazy ways to capture pointers
+      // using comparisons.
       return true;
     default:
       // Something else - be conservative and say it is captured.