Merge pull request swiftlang#83909 from DougGregor/embedded-darwin-reserve-4kb

[Embedded] Only reserve 4KB in embedded Darwin targets

Author: DougGregor

lib/IRGen/SwiftTargetInfo.cpp

@@ -49,7 +49,10 @@ static void configureARM64(IRGenModule &IGM, const llvm::Triple &triple,
   }
   setToMask(target.IsObjCPointerBit, 64, SWIFT_ABI_ARM64_IS_OBJC_BIT);
 
-  if (triple.isOSDarwin()) {
+  // Non-embedded Darwin reserves the low 4GB of address space.
+  if (triple.isOSDarwin() &&
+      !IGM.getSwiftModule()->getASTContext().LangOpts.hasFeature(
+          Feature::Embedded)) {
     target.LeastValidPointerValue =
       SWIFT_ABI_DARWIN_ARM64_LEAST_VALID_POINTER;
   }
@@ -104,7 +107,9 @@ static void configureX86_64(IRGenModule &IGM, const llvm::Triple &triple,
               SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK);
   }
 
-  if (triple.isOSDarwin()) {
+  if (triple.isOSDarwin() &&
+      !IGM.getSwiftModule()->getASTContext().LangOpts.hasFeature(
+          Feature::Embedded)) {
     target.LeastValidPointerValue =
       SWIFT_ABI_DARWIN_X86_64_LEAST_VALID_POINTER;
   }

test/embedded/min-pointer-value-default-darwin.swift

@@ -0,0 +1,22 @@
+
+// RUN: %target-swift-emit-ir %s -module-name main -parse-as-library -enable-experimental-feature Embedded -O -min-valid-pointer-value=0x1000  | %FileCheck %s
+// RUN: %target-swift-emit-ir %s -module-name main -parse-as-library -enable-experimental-feature Embedded -O | %FileCheck %s
+
+// REQUIRES: OS=macosx
+// REQUIRES: swift_feature_Embedded
+
+public func testit(_ s: S?) -> Bool {
+  return s != nil
+}
+
+class C {}
+
+public struct S {
+  var a = InlineArray<57, UInt8>(repeating: 0)
+  var b = C()
+  var c = InlineArray<49, UInt8>(repeating: 0)
+}
+
+// CHECK-LABEL: define {{.*}} @"$e4main1SVSgWOg"(ptr %0)
+// CHECK:         icmp {{.*}}, 4095
+// CHECK-LABEL: }