Merge pull request #84948 from DougGregor/extern-c-asmname

[SILGen] Map the @_extern(c) C function name over to the asmname of a SIL function

lib/SIL/IR/SILDeclRef.cpp

@@ -1428,11 +1428,6 @@ std::string SILDeclRef::mangle(ManglingKind MKind) const {
         return NameA->Name.str();
       }
 
-    if (auto *ExternA = ExternAttr::find(getDecl()->getAttrs(), ExternKind::C)) {
-      assert(isa<FuncDecl>(getDecl()) && "non-FuncDecl with @_extern should be rejected by typechecker");
-      return ExternA->getCName(cast<FuncDecl>(getDecl())).str();
-    }
-
     // Use a given cdecl name for native-to-foreign thunks.
     if (getDecl()->getAttrs().hasAttribute<CDeclAttr>())
       if (isNativeToForeignThunk()) {

lib/SIL/IR/SILFunctionBuilder.cpp

@@ -126,6 +126,12 @@ void SILFunctionBuilder::addFunctionAttributes(
         F->setEffectsKind(effectsAttr->getKind());
       }
     }
+
+    if (constant.isFunc() && constant.hasFuncDecl()) {
+      auto func = constant.getFuncDecl();
+      if (auto *EA = ExternAttr::find(Attrs, ExternKind::C))
+        F->setAsmName(EA->getCName(func));
+    }
   }
 
   if (!customEffects.empty()) {

lib/Serialization/Serialization.cpp

@@ -975,7 +975,7 @@ void Serializer::writeBlockInfoBlock() {
   BLOCK_RECORD(sil_block, SIL_SOURCE_LOC_REF);
   BLOCK_RECORD(sil_block, SIL_DEBUG_VALUE);
   BLOCK_RECORD(sil_block, SIL_DEBUG_VALUE_DELIMITER);
-
+  BLOCK_RECORD(sil_block, SIL_EXTRA_STRING);
 
   BLOCK(SIL_INDEX_BLOCK);
   BLOCK_RECORD(sil_index_block, SIL_FUNC_NAMES);

test/SIL/Serialization/Inputs/extern_with_nonnull.swift

@@ -0,0 +1,8 @@
+@_extern(c, "takes_a_void_pointer")
+public func takes_a_void_pointer(_ pointer: UnsafeRawPointer)
+
+@_alwaysEmitIntoClient
+public func callWithNonNull() {
+  let pointer = UnsafeMutablePointer<Int>.allocate(capacity: 1)
+  takes_a_void_pointer(UnsafeRawPointer(pointer))
+}

test/SIL/Serialization/Inputs/extern_with_nullable.swift

@@ -0,0 +1,7 @@
+@_extern(c, "takes_a_void_pointer")
+public func takes_a_void_pointer(_ pointer: UnsafeRawPointer?)
+
+@_alwaysEmitIntoClient
+public func callWithNullable() {
+  takes_a_void_pointer(nil)
+}

test/SIL/Serialization/extern_collision.swift

@@ -0,0 +1,18 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -emit-module -enable-experimental-feature Extern -o %t %S/Inputs/extern_with_nullable.swift
+// RUN: %target-swift-frontend -emit-module -enable-experimental-feature Extern -o %t %S/Inputs/extern_with_nonnull.swift
+// RUN: %target-swift-frontend -emit-sil -o %t -I %t -primary-file %s -module-name main -O
+
+// REQUIRES: swift_feature_Extern
+
+// Don't crash or otherwise fail when inlining multiple functions that reference
+// @_extern(c) declarations of the same name but different types at the SIL
+// level.
+
+import extern_with_nullable
+import extern_with_nonnull
+
+public func main() {
+  callWithNullable()
+  callWithNonNull()
+}

test/SILGen/extern_c.swift

@@ -2,48 +2,48 @@
 
 // REQUIRES: swift_feature_Extern
 
-// CHECK-DAG: sil hidden_external @my_c_name : $@convention(c) (Int) -> Int
+// CHECK-DAG: sil hidden_external [asmname "my_c_name"] @$s8extern_c9withCNameyS2iFTo : $@convention(c) (Int) -> Int
 @_extern(c, "my_c_name")
 func withCName(_ x: Int) -> Int
 
-// CHECK-DAG: sil hidden_external @take_c_func_ptr : $@convention(c) (@convention(c) (Int) -> Int) -> ()
+// CHECK-DAG: sil hidden_external [asmname "take_c_func_ptr"] @$s8extern_c12takeCFuncPtryyS2iXCF : $@convention(c) (@convention(c) (Int) -> Int) -> ()
 @_extern(c, "take_c_func_ptr")
 func takeCFuncPtr(_ f: @convention(c) (Int) -> Int)
 
-// CHECK-DAG: sil @public_visible : $@convention(c) (Int) -> Int
+// CHECK-DAG: sil [asmname "public_visible"] @$s8extern_c16publicVisibilityyS2iF : $@convention(c) (Int) -> Int
 @_extern(c, "public_visible")
 public func publicVisibility(_ x: Int) -> Int
 
-// CHECK-DAG: sil @private_visible : $@convention(c) (Int) -> Int
+// CHECK-DAG: sil [asmname "private_visible"] @$s8extern_c17privateVisibility{{.*}} : $@convention(c) (Int) -> Int
 @_extern(c, "private_visible")
 private func privateVisibility(_ x: Int) -> Int
 
-// CHECK-DAG: sil hidden_external @withoutCName : $@convention(c) () -> Int
+// CHECK-DAG: sil hidden_external [asmname "withoutCName"] @$s8extern_c12withoutCNameSiyF : $@convention(c) () -> Int
 @_extern(c)
 func withoutCName() -> Int
 
 // CHECK-DAG: sil hidden [ossa] @$s8extern_c10defaultArgyySiFfA_ : $@convention(thin) () -> Int {
-// CHECK-DAG: sil hidden_external @default_arg : $@convention(c) (Int) -> ()
+// CHECK-DAG: sil hidden_external [asmname "default_arg"] @$s8extern_c10defaultArgyySiF : $@convention(c) (Int) -> ()
 @_extern(c, "default_arg")
 func defaultArg(_ x: Int = 42)
 
 func main() {
-  // CHECK-DAG: [[F1:%.+]] = function_ref @my_c_name : $@convention(c) (Int) -> Int
-  // CHECK-DAG: [[F2:%.+]] = function_ref @take_c_func_ptr : $@convention(c) (@convention(c) (Int) -> Int) -> ()
+  // CHECK-DAG: [[F1:%.+]] = function_ref @$s8extern_c9withCNameyS2iFTo : $@convention(c) (Int) -> Int
+  // CHECK-DAG: [[F2:%.+]] = function_ref @$s8extern_c12takeCFuncPtryyS2iXCF : $@convention(c) (@convention(c) (Int) -> Int) -> ()
   // CHECK-DAG: apply [[F2]]([[F1]]) : $@convention(c) (@convention(c) (Int) -> Int) -> ()
   takeCFuncPtr(withCName)
-  // CHECK-DAG: [[F3:%.+]] = function_ref @public_visible : $@convention(c) (Int) -> Int
+  // CHECK-DAG: [[F3:%.+]] = function_ref @$s8extern_c16publicVisibilityyS2iF : $@convention(c) (Int) -> Int
   // CHECK-DAG: apply [[F3]]({{.*}}) : $@convention(c) (Int) -> Int
   _ = publicVisibility(42)
-  // CHECK-DAG: [[F4:%.+]] = function_ref @private_visible : $@convention(c) (Int) -> Int
+  // CHECK-DAG: [[F4:%.+]] = function_ref @$s8extern_c17privateVisibility{{.*}} : $@convention(c) (Int) -> Int
   // CHECK-DAG: apply [[F4]]({{.*}}) : $@convention(c) (Int) -> Int
   _ = privateVisibility(24)
-  // CHECK-DAG: [[F5:%.+]] = function_ref @withoutCName : $@convention(c) () -> Int
+  // CHECK-DAG: [[F5:%.+]] = function_ref @$s8extern_c12withoutCNameSiyF : $@convention(c) () -> Int
   // CHECK-DAG: apply [[F5]]() : $@convention(c) () -> Int
   _ = withoutCName()
   // CHECK-DAG: [[F6:%.+]] = function_ref @$s8extern_c10defaultArgyySiFfA_ : $@convention(thin) () -> Int
   // CHECK-DAG: [[DEFAULT_V:%.+]] = apply [[F6]]() : $@convention(thin) () -> Int
-  // CHECK-DAG: [[F7:%.+]] = function_ref @default_arg : $@convention(c) (Int) -> ()
+  // CHECK-DAG: [[F7:%.+]] = function_ref @$s8extern_c10defaultArgyySiF : $@convention(c) (Int) -> ()
   // CHECK-DAG: apply [[F7]]([[DEFAULT_V]]) : $@convention(c) (Int) -> ()
   defaultArg()
 }

test/SILGen/silgen_name_conflict.swift

@@ -9,7 +9,7 @@ func my_extern_func1() // expected-note {{function declared here}}
 func my_extern_func2(x: Int)
 
 @_extern(c, "my_other_extern_func")
-func my_other_extern_func1() // expected-note {{function declared here}}
+func my_other_extern_func1()
 
 @_extern(c, "my_other_extern_func")
 func my_other_extern_func2(x: Int)
@@ -18,6 +18,8 @@ public func foo() {
     my_extern_func1()
     my_extern_func2(x: 42) // expected-error {{function type mismatch, declared as '@convention(thin) () -> ()' but used as '@convention(thin) (Int) -> ()'}}
 
+    // @_extern(c, ...) keeps declarations separate at the SIL level, so we do
+    // not detect a mismatch here.
     my_other_extern_func1()
-    my_other_extern_func2(x: 42) // expected-error {{function type mismatch, declared as '@convention(c) () -> ()' but used as '@convention(c) (Int) -> ()'}}
+    my_other_extern_func2(x: 42)
 }

test/embedded/wrong-linkage.swift

@@ -4,6 +4,6 @@
 // REQUIRES: OS=macosx
 
 @_cdecl("posix_memalign")
-func posix_memalign(_ resultPtr:UnsafeMutablePointer<UnsafeMutableRawPointer?>, _ :Int, _ :Int) -> Int32 { // expected-error {{function has wrong linkage to be called from}}
+func posix_memalign(_ resultPtr:UnsafeMutablePointer<UnsafeMutableRawPointer?>, _ :Int, _ :Int) -> Int32 { // okay: @_extern(c) declaration is separate
   return 0
 }