COWArrayOpts: make the optimization work again for two-dimensional arrays.

With removing of pinning and with addressors, the pattern matching did not work anymore.
The good thing is that the SIL is now much simpler and we can handle the 2D case without pattern matching at all.
This removes a lot of code from COWArrayOpts.

rdar://problem/43863081

Author: eeckstein

include/swift/SIL/InstructionUtils.h

@@ -57,10 +57,6 @@ SILValue stripAddressAccess(SILValue V);
 /// instructions.
 SILValue stripAddressProjections(SILValue V);
 
-/// Return the underlying SILValue after stripping off all address projection
-/// instructions which have a single operand.
-SILValue stripUnaryAddressProjections(SILValue V);
-
 /// Return the underlying SILValue after stripping off all aggregate projection
 /// instructions.
 ///

include/swift/SILOptimizer/Utils/Local.h

@@ -600,13 +600,6 @@ SILType getExactDynamicType(SILValue S, SILModule &M,
 SILType getExactDynamicTypeOfUnderlyingObject(SILValue S, SILModule &M,
                                               ClassHierarchyAnalysis *CHA);
 
-/// Hoist the address projection rooted in \p Op to \p InsertBefore.
-/// Requires the projected value to dominate the insertion point.
-///
-/// Will look through single basic block predecessor arguments.
-void hoistAddressProjections(Operand &Op, SILInstruction *InsertBefore,
-                             DominanceInfo *DomTree);
-
 /// Utility class for cloning init values into the static initializer of a
 /// SILGlobalVariable.
 class StaticInitCloner : public SILCloner<StaticInitCloner> {

lib/SIL/InstructionUtils.cpp

@@ -203,18 +203,6 @@ SILValue swift::stripAddressProjections(SILValue V) {
   }
 }
 
-SILValue swift::stripUnaryAddressProjections(SILValue V) {
-  while (true) {
-    V = stripSinglePredecessorArgs(V);
-    if (!Projection::isAddressProjection(V))
-      return V;
-    auto *Inst = cast<SingleValueInstruction>(V);
-    if (Inst->getNumOperands() > 1)
-      return V;
-    V = Inst->getOperand(0);
-  }
-}
-
 SILValue swift::stripValueProjections(SILValue V) {
   while (true) {
     V = stripSinglePredecessorArgs(V);