[llvm] r229443 - RegisterCoalescer: Do not look for regclass of IMPLICIT_DEF.

[Matthias Braun]

Author: matze
Date: Mon Feb 16 16:05:12 2015
New Revision: 229443

URL: http://llvm.org/viewvc/llvm-project?rev=229443&view=rev
Log:
RegisterCoalescer: Do not look for regclass of IMPLICIT_DEF.

IMPLICIT_DEF is a generic instruction and has no (fixed) output register
class defined. The rematerialization code of the register coalescer
should not scan the instruction description for a register class.

This fixes a problem showing up in
test/CodeGen/R600/subreg-coalescer-crash.ll with subregister liveness
enabled.

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=229443&r1=229442&r2=229443&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Mon Feb 16 16:05:12 2015
@@ -913,12 +913,13 @@ bool RegisterCoalescer::reMaterializeTri
     const TargetRegisterClass *NewRC = CP.getNewRC();
     unsigned NewIdx = NewMI->getOperand(0).getSubReg();
 
-    if (NewIdx)
-      NewRC = TRI->getMatchingSuperRegClass(NewRC, DefRC, NewIdx);
-    else
-      NewRC = TRI->getCommonSubClass(NewRC, DefRC);
-
-    assert(NewRC && "subreg chosen for remat incompatible with instruction");
+    if (DefRC != nullptr) {
+      if (NewIdx)
+        NewRC = TRI->getMatchingSuperRegClass(NewRC, DefRC, NewIdx);
+      else
+        NewRC = TRI->getCommonSubClass(NewRC, DefRC);
+      assert(NewRC && "subreg chosen for remat incompatible with instruction");
+    }
     MRI->setRegClass(DstReg, NewRC);
 
     updateRegDefsUses(DstReg, DstReg, DstIdx);