Merge pull request #42064 from meg-gupta/opaquevaluework

[SIL Opaque values] Add support for unchecked_bitwise_cast in AddressLowering

Author: meg-gupta

lib/SILOptimizer/Mandatory/AddressLowering.cpp

@@ -798,6 +798,8 @@ static Operand *getProjectedDefOperand(SILValue value) {
 /// is address-only, then the operand must be address-only and therefore must
 /// mapped to ValueStorage.
 ///
+/// If \p value is an unchecked_bitwise_cast, then return the cast operand.
+///
 /// open_existential_value must reuse storage because the boxed value is shared
 /// with other instances of the existential. An explicit copy is needed to
 /// obtain an owned value.
@@ -812,6 +814,7 @@ static Operand *getReusedStorageOperand(SILValue value) {
   case ValueKind::OpenExistentialValueInst:
   case ValueKind::OpenExistentialBoxValueInst:
   case ValueKind::UncheckedEnumDataInst:
+  case ValueKind::UncheckedBitwiseCastInst:
     return &cast<SingleValueInstruction>(value)->getOperandRef(0);
 
   case ValueKind::SILPhiArgument: {
@@ -2551,9 +2554,16 @@ class UseRewriter : SILInstructionVisitor<UseRewriter> {
   // Extract from an opaque tuple.
   void visitTupleExtractInst(TupleExtractInst *extractInst);
 
-  void visitUncheckedBitwiseCast(UncheckedBitwiseCastInst *uncheckedCastInst) {
-    // FIXME: Unimplemented
-    llvm::report_fatal_error("Unimplemented UncheckedBitwiseCast use.");
+  void
+  visitUncheckedBitwiseCastInst(UncheckedBitwiseCastInst *uncheckedCastInst) {
+    SILValue srcVal = uncheckedCastInst->getOperand();
+    SILValue srcAddr = pass.valueStorageMap.getStorage(srcVal).storageAddress;
+
+    auto destAddr = builder.createUncheckedAddrCast(
+        uncheckedCastInst->getLoc(), srcAddr,
+        uncheckedCastInst->getType().getAddressType());
+
+    markRewritten(uncheckedCastInst, destAddr);
   }
 
   void visitUncheckedEnumDataInst(UncheckedEnumDataInst *enumDataInst);

test/SILOptimizer/address_lowering.sil

@@ -1169,3 +1169,22 @@ bb1(%3 : @owned $(T, Int, Int, T)):
 bb2(%9 : $Error):
   throw %9 : $Error
 }
+
+// CHECK-LABEL: sil hidden [ossa] @test_unchecked_bitwise_cast :
+// CHECK: bb0(%0 : $*U, %1 : $*T, %2 : $@thick U.Type):
+// CHECK:   [[STK:%.*]] = alloc_stack $T
+// CHECK:   copy_addr %1 to [initialization] [[STK]] : $*T
+// CHECK:   [[CAST:%.*]] = unchecked_addr_cast [[STK]] : $*T to $*U
+// CHECK:   copy_addr [[CAST]] to [initialization] %0 : $*U
+// CHECK:   destroy_addr [[STK]] : $*T
+// CHECK:   dealloc_stack [[STK]] : $*T
+// CHECK-LABEL: } // end sil function 'test_unchecked_bitwise_cast'
+sil hidden [ossa] @test_unchecked_bitwise_cast : $@convention(thin) <T, U> (@in_guaranteed T, @thick U.Type) -> @out U {
+bb0(%0 : @guaranteed $T, %1 : $@thick U.Type):
+  %4 = copy_value %0 : $T
+  %5 = unchecked_bitwise_cast %4 : $T to $U
+  %6 = copy_value %5 : $U
+  destroy_value %4 : $T
+  return %6 : $U
+}
+