1. Implement SDValue simplifyAssumingCCVal to evaluate Val under the assumption that CC actually results in the numerical condition code value CCVal, and return vector of CCVals for each position.

2. Implement findCCUse routine that finds a CC that is used as condition code and the associated CCValid mask.
3. Code related to select_ccmask in combineCCMask has been removed, as this computation has been done in new framework.
4. Remove combineLogicalOpCCMask as simplifyAssumingCCVal fully recurses through logical operations.

Author: anoopkg6

llvm/lib/Target/SystemZ/SystemZ.h

@@ -24,6 +24,7 @@ class SystemZTargetMachine;
 
 namespace SystemZ {
 // Condition-code mask values.
+const unsigned CCMASK_NONE = 0;
 const unsigned CCMASK_0 = 1 << 3;
 const unsigned CCMASK_1 = 1 << 2;
 const unsigned CCMASK_2 = 1 << 1;