[llvm-commits] [llvm] r153517 - /llvm/trunk/lib/CodeGen/BranchFolding.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Tue Mar 27 12:06:09 2012
New Revision: 153517

URL: http://llvm.org/viewvc/llvm-project?rev=153517&view=rev
Log:
Branch folding may invalidate liveness.

Branch folding can use a register scavenger to update liveness
information when required. Don't do that if liveness information is
already invalid.

Modified:
    llvm/trunk/lib/CodeGen/BranchFolding.cpp

Modified: llvm/trunk/lib/CodeGen/BranchFolding.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/BranchFolding.cpp?rev=153517&r1=153516&r2=153517&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/BranchFolding.cpp (original)
+++ llvm/trunk/lib/CodeGen/BranchFolding.cpp Tue Mar 27 12:06:09 2012
@@ -23,6 +23,7 @@
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
@@ -183,8 +184,14 @@
   TII = tii;
   TRI = tri;
   MMI = mmi;
+  RS = NULL;
 
-  RS = TRI->requiresRegisterScavenging(MF) ? new RegScavenger() : NULL;
+  // Use a RegScavenger to help update liveness when required.
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  if (MRI.tracksLiveness() && TRI->requiresRegisterScavenging(MF))
+    RS = new RegScavenger();
+  else
+    MRI.invalidateLiveness();
 
   // Fix CFG.  The later algorithms expect it to be right.
   bool MadeChange = false;