Preserve implicit defs in ARMLoadStoreOptimizer.

When a number of sub-register VLRDS instructions are combined into a
VLDM, preserve any super-register implicit defs. This is required to
keep the register scavenger and machine code verifier happy.

Enable machine code verification after ARMLoadStoreOptimizer.
ARM/2012-01-26-CopyPropKills.ll was failing because of this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153610 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMTargetMachine.cpp b/lib/Target/ARM/ARMTargetMachine.cpp
index 44229ad..22b696c 100644
--- a/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/lib/Target/ARM/ARMTargetMachine.cpp
@@ -158,8 +158,10 @@
 bool ARMPassConfig::addPreSched2() {
   // FIXME: temporarily disabling load / store optimization pass for Thumb1.
   if (getOptLevel() != CodeGenOpt::None) {
-    if (!getARMSubtarget().isThumb1Only())
+    if (!getARMSubtarget().isThumb1Only()) {
       PM.add(createARMLoadStoreOptimizationPass());
+      printAndVerify("After ARM load / store optimizer");
+    }
     if (getARMSubtarget().hasNEON())
       PM.add(createExecutionDependencyFixPass(&ARM::DPRRegClass));
   }