[llvm-commits] [llvm] r166763 - in /llvm/trunk: include/llvm/CodeGen/GCMetadata.h lib/CodeGen/GCStrategy.cpp

[Nicolas Geoffray]

Author: geoffray
Date: Fri Oct 26 04:15:55 2012
New Revision: 166763

URL: http://llvm.org/viewvc/llvm-project?rev=166763&view=rev
Log:
Remove GC roots that reference dead objects.


Modified:
    llvm/trunk/include/llvm/CodeGen/GCMetadata.h
    llvm/trunk/lib/CodeGen/GCStrategy.cpp

Modified: llvm/trunk/include/llvm/CodeGen/GCMetadata.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/GCMetadata.h?rev=166763&r1=166762&r2=166763&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/GCMetadata.h (original)
+++ llvm/trunk/include/llvm/CodeGen/GCMetadata.h Fri Oct 26 04:15:55 2012
@@ -122,6 +122,11 @@
       Roots.push_back(GCRoot(Num, Metadata));
     }
 
+    /// removeStackRoot - Removes a root.
+    roots_iterator removeStackRoot(roots_iterator position) {
+      return Roots.erase(position);
+    }
+
     /// addSafePoint - Notes the existence of a safe point. Num is the ID of the
     /// label just prior to the safe point (if the code generator is using
     /// MachineModuleInfo).

Modified: llvm/trunk/lib/CodeGen/GCStrategy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GCStrategy.cpp?rev=166763&r1=166762&r2=166763&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GCStrategy.cpp (original)
+++ llvm/trunk/lib/CodeGen/GCStrategy.cpp Fri Oct 26 04:15:55 2012
@@ -388,9 +388,16 @@
   const TargetFrameLowering *TFI = TM->getFrameLowering();
   assert(TFI && "TargetRegisterInfo not available!");
 
-  for (GCFunctionInfo::roots_iterator RI = FI->roots_begin(),
-                                      RE = FI->roots_end(); RI != RE; ++RI)
-    RI->StackOffset = TFI->getFrameIndexOffset(MF, RI->Num);
+  for (GCFunctionInfo::roots_iterator RI = FI->roots_begin();
+       RI != FI->roots_end();) {
+    // If the root references a dead object, no need to keep it.
+    if (MF.getFrameInfo()->isDeadObjectIndex(RI->Num)) {
+      RI = FI->removeStackRoot(RI);
+    } else {
+      RI->StackOffset = TFI->getFrameIndexOffset(MF, RI->Num);
+      ++RI;
+    }
+  }
 }
 
 bool GCMachineCodeAnalysis::runOnMachineFunction(MachineFunction &MF) {