[llvm-commits] [llvm] r164807 - /llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Thu Sep 27 18:31:32 2012
New Revision: 164807

URL: http://llvm.org/viewvc/llvm-project?rev=164807&view=rev
Log:
Remove <def,read-undef> flags from partial redefinitions.

The new coalescer can turn a full virtual register definition into a
partial redef by merging another value into an unused vector lane.

Make sure to clear the <read-undef> flag on such defs.

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

Modified: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp?rev=164807&r1=164806&r2=164807&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Thu Sep 27 18:31:32 2012
@@ -1732,6 +1732,12 @@
     case CR_Replace:
       // This value takes precedence over the value in Other.LI.
       LIS->pruneValue(&Other.LI, Def, &EndPoints);
+      // Remove <def,read-undef> flags. This def is now a partial redef.
+      if (!Def.isBlock())
+        for (MIOperands MO(Indexes->getInstructionFromIndex(Def));
+             MO.isValid(); ++MO)
+          if (MO->isReg() && MO->isDef() && MO->getReg() == LI.reg)
+            MO->setIsUndef(false);
       DEBUG(dbgs() << "\t\tpruned " << PrintReg(Other.LI.reg) << " at " << Def
                    << ": " << Other.LI << '\n');
       break;