StackProtection: treat source-operands of memcpy and memmove intrinsics as read-only

SwiftCompilerSources/Sources/Optimizer/ModulePasses/StackProtection.swift

@@ -524,10 +524,19 @@ private struct NoStores : ValueDefUseWalker, AddressDefUseWalker {
   var walkDownCache = WalkerCache<SmallProjectionPath>()
 
   mutating func leafUse(value: Operand, path: SmallProjectionPath) -> WalkResult {
-    if let ptai = value.instruction as? PointerToAddressInst {
+    switch value.instruction {
+    case let ptai as PointerToAddressInst:
       return walkDownUses(ofAddress: ptai, path: path)
+    case let bi as BuiltinInst:
+      switch bi.intrinsicID {
+      case .memcpy, .memmove:
+        return value.index != 0 ? .continueWalk : .abortWalk
+      default:
+        return .abortWalk
+      }
+    default:
+      return .abortWalk
     }
-    return .abortWalk
   }
 
   mutating func leafUse(address: Operand, path: SmallProjectionPath) -> WalkResult {

SwiftCompilerSources/Sources/SIL/Instruction.swift

@@ -399,6 +399,10 @@ final public class BuiltinInst : SingleValueInstruction {
     return bridged.BuiltinInst_getID()
   }
 
+  public var intrinsicID: BridgedInstruction.IntrinsicID {
+    return bridged.BuiltinInst_getIntrinsicID()
+  }
+
   public var substitutionMap: SubstitutionMap {
     SubstitutionMap(bridged.BuiltinInst_getSubstitutionMap())
   }

include/swift/SIL/SILBridging.h

@@ -525,6 +525,19 @@ struct BridgedInstruction {
     return getAs<swift::BuiltinInst>()->getBuiltinInfo().ID;
   }
 
+  enum class IntrinsicID {
+    memcpy, memmove,
+    unknown
+  };
+
+  IntrinsicID BuiltinInst_getIntrinsicID() const {
+    switch (getAs<swift::BuiltinInst>()->getIntrinsicInfo().ID) {
+      case llvm::Intrinsic::memcpy:  return IntrinsicID::memcpy;
+      case llvm::Intrinsic::memmove: return IntrinsicID::memmove;
+      default: return IntrinsicID::unknown;
+    }
+  }
+
   SWIFT_IMPORT_UNSAFE
   swift::SubstitutionMap BuiltinInst_getSubstitutionMap() const {
     return getAs<swift::BuiltinInst>()->getSubstitutions();

test/SILOptimizer/stack_protection.sil

@@ -676,4 +676,20 @@ bb0:
   return %12 : $()
 }
 
+// CHECK-LABEL: sil @test_mem_intrinsics
+// CHECK-NOT:     copy_addr
+// CHECK:       } // end sil function 'test_mem_intrinsics'
+sil @test_mem_intrinsics : $@convention(thin) (Builtin.RawPointer, Int64) -> () {
+bb0(%0 : $Builtin.RawPointer, %1: $Int64):
+  %2 = alloc_stack $Int64
+  store %1 to %2 : $*Int64
+  %4 = address_to_pointer [stack_protection] %2 : $*Int64 to $Builtin.RawPointer
+  %5 = integer_literal $Builtin.Int64, 8
+  %6 = integer_literal $Builtin.Int1, 0
+  %7 = builtin "int_memcpy_RawPointer_RawPointer_Int64"(%0 : $Builtin.RawPointer, %4 : $Builtin.RawPointer, %5 : $Builtin.Int64, %6 : $Builtin.Int1) : $()
+  %8 = builtin "int_memmove_RawPointer_RawPointer_Int64"(%0 : $Builtin.RawPointer, %4 : $Builtin.RawPointer, %5 : $Builtin.Int64, %6 : $Builtin.Int1) : $()
+  dealloc_stack %2 : $*Int64
+  %10 = tuple ()
+  return %10 : $()
+}
 

test/SILOptimizer/stack_protection.swift

@@ -118,3 +118,10 @@ public func loadUnaligned(_ urp: UnsafeRawPointer) -> Int {
   return urp.loadUnaligned(as: Int.self)
 }
 
+// CHECK-LABEL: sil @$s4test19storeBytesToPointeryySv_SitF :
+// CHECK-NOT:     copy_addr
+// CHECK:       } // end sil function '$s4test19storeBytesToPointeryySv_SitF'
+public func storeBytesToPointer(_ p: UnsafeMutableRawPointer, _ i: Int) {
+  p.storeBytes(of: i, as: Int.self)
+}
+