CSE: Don't look through ownership instructions for "escaped" values

CSE relies on OSSA RAUW for lifetime extension when replacing a redundant instruction.
OSSA RAUW however does not handle lifetime extension for the base value of an escaped value.
Values escape from ownership via pointer escape, bitwise escape, forwarding unowned operations
and have none or unowned ownership. For all such values do not look through ownership instructions
while determining equality. It is possible to CSE such values with equivalent operands, because the
operand use guarantees lifetime of the base operand.

Author: meg-gupta

include/swift/SIL/SILInstruction.h

@@ -643,7 +643,7 @@ class SILInstruction : public llvm::ilist_node<SILInstruction> {
   NonTypeDependentOperandValueRange getNonTypeDependentOperandValues() const;
 
   TransformedOperandValueRange
-  getOperandValues(std::function<SILValue(SILValue)> transformFn,
+  getOperandValues(std::function<SILValue(const Operand *)> transformFn,
                    bool skipTypeDependentOperands) const;
 
   SILValue getOperand(unsigned Num) const {
@@ -720,8 +720,8 @@ class SILInstruction : public llvm::ilist_node<SILInstruction> {
   /// Returns true if the given instruction is completely identical to RHS,
   /// using \p opEqual to compare operands.
   ///
-  template <typename OpCmp>
-  bool isIdenticalTo(const SILInstruction *RHS, OpCmp &&opEqual) const {
+  bool isIdenticalTo(const SILInstruction *RHS,
+                     std::function<bool(SILValue, SILValue)> opEqual) const {
     // Quick check if both instructions have the same kind, number of operands,
     // and types. This should filter out most cases.
     if (getKind() != RHS->getKind() ||
@@ -742,6 +742,29 @@ class SILInstruction : public llvm::ilist_node<SILInstruction> {
     return hasIdenticalState(RHS);
   }
 
+  bool isIdenticalTo(
+      const SILInstruction *RHS,
+      std::function<bool(const Operand *, const Operand *)> opEqual) const {
+    // Quick check if both instructions have the same kind, number of operands,
+    // and types. This should filter out most cases.
+    if (getKind() != RHS->getKind() ||
+        getNumOperands() != RHS->getNumOperands()) {
+      return false;
+    }
+
+    if (!getResults().hasSameTypes(RHS->getResults()))
+      return false;
+
+    // Check operands.
+    for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
+      if (!opEqual(&getOperandRef(i), &RHS->getOperandRef(i)))
+        return false;
+
+    // Check any special state of instructions that are not represented in the
+    // instructions operands/type.
+    return hasIdenticalState(RHS);
+  }
+
   /// Returns true if the instruction may have side effects.
   ///
   /// Instructions that store into memory or change retain counts as well as
@@ -972,19 +995,20 @@ struct SILInstruction::NonTypeDependentOperandToValue {
 
 struct SILInstruction::OperandToTransformedValue {
   const SILInstruction &i;
-  std::function<SILValue(SILValue)> transformFn;
+  std::function<SILValue(const Operand *)> transformFn;
   bool skipTypeDependentOps;
 
-  OperandToTransformedValue(const SILInstruction &i,
-                            std::function<SILValue(SILValue)> transformFn,
-                            bool skipTypeDependentOps)
+  OperandToTransformedValue(
+      const SILInstruction &i,
+      std::function<SILValue(const Operand *)> transformFn,
+      bool skipTypeDependentOps)
       : i(i), transformFn(transformFn),
         skipTypeDependentOps(skipTypeDependentOps) {}
 
   Optional<SILValue> operator()(const Operand &use) const {
     if (skipTypeDependentOps && i.isTypeDependentOperand(use))
       return None;
-    return transformFn(use.get());
+    return transformFn(&use);
   }
 };
 
@@ -1005,10 +1029,9 @@ SILInstruction::getNonTypeDependentOperandValues() const
                                            NonTypeDependentOperandToValue(*this));
 }
 
-inline auto
-SILInstruction::getOperandValues(std::function<SILValue(SILValue)> transformFn,
-                                 bool skipTypeDependentOperands) const
-    -> TransformedOperandValueRange {
+inline auto SILInstruction::getOperandValues(
+    std::function<SILValue(const Operand *)> transformFn,
+    bool skipTypeDependentOperands) const -> TransformedOperandValueRange {
   return TransformedOperandValueRange(
       getAllOperands(),
       OperandToTransformedValue(*this, transformFn, skipTypeDependentOperands));
@@ -6539,7 +6562,8 @@ class SelectEnumInstBase
 
   SILValue getOperand() const { return getAllOperands()[0].get(); }
   SILValue getEnumOperand() const { return getOperand(); }
-  
+  const Operand &getEnumOperandRef() const { return getAllOperands()[0]; }
+
   std::pair<EnumElementDecl*, SILValue>
   getCase(unsigned i) const {
     return std::make_pair(getEnumElementDeclStorage()[i],