Fix the IR gen for C++ method calls and refactor around CGFunctionInfo

lib/ClangImporter/ImportType.cpp

@@ -2203,10 +2203,11 @@ ImportedType ClangImporter::Implementation::importFunctionReturnType(
   // C++ operators +=, -=, *=, /= may return a reference to self. This is not
   // idiomatic in Swift, let's drop these return values.
   clang::OverloadedOperatorKind op = clangDecl->getOverloadedOperator();
-  if (op == clang::OverloadedOperatorKind::OO_PlusEqual ||
-      op == clang::OverloadedOperatorKind::OO_MinusEqual ||
-      op == clang::OverloadedOperatorKind::OO_StarEqual ||
-      op == clang::OverloadedOperatorKind::OO_SlashEqual)
+  if ((op == clang::OverloadedOperatorKind::OO_PlusEqual ||
+       op == clang::OverloadedOperatorKind::OO_MinusEqual ||
+       op == clang::OverloadedOperatorKind::OO_StarEqual ||
+       op == clang::OverloadedOperatorKind::OO_SlashEqual) &&
+      clangDecl->getReturnType()->isReferenceType())
     return {SwiftContext.getVoidType(), false};
 
   // Fix up optionality.

lib/IRGen/GenCall.cpp

@@ -1471,9 +1471,15 @@ void SignatureExpansion::expandExternalSignatureTypes() {
   // Generate function info for this signature.
   auto extInfo = clang::FunctionType::ExtInfo();
 
-  auto &FI = clang::CodeGen::arrangeFreeFunctionCall(IGM.ClangCodeGen->CGM(),
-                                             clangResultTy, paramTys, extInfo,
-                                             clang::CodeGen::RequiredArgs::All);
+  bool isCXXMethod =
+      FnType->getRepresentation() == SILFunctionTypeRepresentation::CXXMethod;
+  auto &FI = isCXXMethod ?
+      clang::CodeGen::arrangeCXXMethodCall(IGM.ClangCodeGen->CGM(),
+          clangResultTy, paramTys, extInfo, {},
+          clang::CodeGen::RequiredArgs::All) :
+      clang::CodeGen::arrangeFreeFunctionCall(IGM.ClangCodeGen->CGM(),
+          clangResultTy, paramTys, extInfo, {},
+          clang::CodeGen::RequiredArgs::All);
   ForeignInfo.ClangInfo = &FI;
 
   assert(FI.arg_size() == paramTys.size() &&
@@ -1595,9 +1601,7 @@ void SignatureExpansion::expandExternalSignatureTypes() {
   if (returnInfo.isIndirect()) {
     auto resultType = getSILFuncConventions().getSingleSILResultType(
         IGM.getMaximalTypeExpansionContext());
-    if (IGM.Triple.isWindowsMSVCEnvironment() &&
-        FnType->getRepresentation() ==
-            SILFunctionTypeRepresentation::CXXMethod) {
+    if (returnInfo.isSRetAfterThis()) {
       // Windows ABI places `this` before the
       // returned indirect values.
       emitArg(0);
@@ -2577,11 +2581,12 @@ class SyncCallEmission final : public CallEmission {
 
         // Windows ABI places `this` before the
         // returned indirect values.
-        bool isThisFirst = IGF.IGM.Triple.isWindowsMSVCEnvironment();
-        if (!isThisFirst)
+        auto &returnInfo =
+            getCallee().getForeignInfo().ClangInfo->getReturnInfo();
+        if (returnInfo.isIndirect() && !returnInfo.isSRetAfterThis())
           passIndirectResults();
         adjusted.add(arg);
-        if (isThisFirst)
+        if (returnInfo.isIndirect() && returnInfo.isSRetAfterThis())
           passIndirectResults();
       }
 
@@ -3171,9 +3176,10 @@ void CallEmission::emitToUnmappedMemory(Address result) {
   assert(LastArgWritten == 1 && "emitting unnaturally to indirect result");
 
   Args[0] = result.getAddress();
-  if (IGF.IGM.Triple.isWindowsMSVCEnvironment() &&
-      getCallee().getRepresentation() ==
-          SILFunctionTypeRepresentation::CXXMethod &&
+
+  auto *FI = getCallee().getForeignInfo().ClangInfo;
+  if (FI && FI->getReturnInfo().isIndirect() &&
+      FI->getReturnInfo().isSRetAfterThis() &&
       Args[1] == getCallee().getCXXMethodSelf()) {
     // C++ methods in MSVC ABI pass `this` before the
     // indirectly returned value.
@@ -3566,10 +3572,10 @@ void CallEmission::emitToExplosion(Explosion &out, bool isOutlined) {
       emitToMemory(temp, substResultTI, isOutlined);
       return;
     }
-    if (IGF.IGM.Triple.isWindowsMSVCEnvironment() &&
-        getCallee().getRepresentation() ==
-            SILFunctionTypeRepresentation::CXXMethod &&
-        substResultType.isVoid()) {
+
+    auto *FI = getCallee().getForeignInfo().ClangInfo;
+    if (FI && FI->getReturnInfo().isIndirect() &&
+        FI->getReturnInfo().isSRetAfterThis() && substResultType.isVoid()) {
       // Some C++ methods return a value but are imported as
       // returning `Void` (e.g. `operator +=`). In this case
       // we should allocate the correct temp indirect return

test/Interop/Cxx/class/method/Inputs/inreg-sret.h

@@ -0,0 +1,11 @@
+#ifndef TEST_INTEROP_CXX_CLASS_METHOD_INREG_SRET_H
+#define TEST_INTEROP_CXX_CLASS_METHOD_INREG_SRET_H
+
+struct OptionalBridgedBasicBlock {
+};
+
+struct BridgedFunction {
+  OptionalBridgedBasicBlock getFirstBlock() const { return {}; }
+};
+
+#endif // TEST_INTEROP_CXX_CLASS_METHOD_INREG_SRET_H

test/Interop/Cxx/class/method/Inputs/module.modulemap

@@ -19,3 +19,8 @@ module SRetWinARM64 {
   header "sret-win-arm64.h"
   requires cplusplus
 }
+
+module InRegSRet {
+  header "inreg-sret.h"
+  requires cplusplus
+}

test/Interop/Cxx/class/method/inreg-sret.swift

@@ -0,0 +1,28 @@
+// RUN: %target-swift-emit-irgen -I %S/Inputs -cxx-interoperability-mode=default %s | %FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-%target-cpu
+
+// REQUIRES: OS=windows-msvc
+
+import InRegSRet
+
+final public class BasicBlock {
+}
+
+extension OptionalBridgedBasicBlock {
+  public var block: BasicBlock? { nil }
+}
+
+final public class Function {
+  public var bridged: BridgedFunction {
+    BridgedFunction()
+  }
+
+  public var firstBlock : BasicBlock? { bridged.getFirstBlock().block }
+}
+
+// Check that inreg on the sret isn't missing
+
+// CHECK-x86_64: call void @"?getFirstBlock@BridgedFunction@@QEBA?AUOptionalBridgedBasicBlock@@XZ"(ptr {{.*}}, ptr noalias nocapture sret(%TSo25OptionalBridgedBasicBlockV) {{.*}})
+// CHECK-aarch64: call void @"?getFirstBlock@BridgedFunction@@QEBA?AUOptionalBridgedBasicBlock@@XZ"(ptr {{.*}}, ptr inreg noalias nocapture sret(%TSo25OptionalBridgedBasicBlockV) {{.*}})
+
+// CHECK-x86_64: define {{.*}} void @"?getFirstBlock@BridgedFunction@@QEBA?AUOptionalBridgedBasicBlock@@XZ"(ptr {{.*}} %{{.*}}, ptr noalias sret(%struct.OptionalBridgedBasicBlock) {{.*}} %{{.*}})
+// CHECK-aarch64: define {{.*}} void @"?getFirstBlock@BridgedFunction@@QEBA?AUOptionalBridgedBasicBlock@@XZ"(ptr {{.*}} %{{.*}}, ptr inreg noalias sret(%struct.OptionalBridgedBasicBlock) {{.*}} %{{.*}})

test/Interop/Cxx/class/method/msvc-abi-return-indirect-trivial-record.swift

@@ -57,15 +57,15 @@ public func test(_ result: VecStr) -> CInt {
 }
 
 // CHECK: swiftcc i32 @"$s4Test4testys5Int32VSo0014vecstr_yuJCataVF"({{.*}} %[[RESULT:.*]])
-// CHECK: call void @"?begin@?$vec@Vstr@@@@QEBA?AVIt@@XZ"(ptr %[[RESULT]], ptr sret{{.*}}
+// CHECK: call void @"?begin@?$vec@Vstr@@@@QEBA?AVIt@@XZ"(ptr %[[RESULT]], ptr {{.*}} sret{{.*}}
 
 public func passTempForIndirectRetToVoidCall() {
     var lhs = LoadableIntWrapper(value: 2)
     let rhs = LoadableIntWrapper(value: 2)
     lhs += rhs
 }
 
-// CHECK: void @"$sSo18LoadableIntWrapperV2peoiyyABz_ABtFZ"(ptr
-// CHECK: %[[OPRESULT:.*]] = alloca %struct.LoadableIntWrapper, align 16
-// CHECK-x86_64: call void @"??YLoadableIntWrapper@@QEAA?AU0@U0@@Z"(ptr {{.*}}, ptr sret(%struct.LoadableIntWrapper) %[[OPRESULT]], i32
-// CHECK-aarch64: call void @"??YLoadableIntWrapper@@QEAA?AU0@U0@@Z"(ptr {{.*}}, ptr sret(%struct.LoadableIntWrapper) %[[OPRESULT]], i64
+// CHECK: i32 @"$sSo18LoadableIntWrapperV2peoiyA2Bz_ABtFZ"(ptr
+// CHECK: %[[OPRESULT:.*]] = alloca %TSo18LoadableIntWrapperV, align 4
+// CHECK-x86_64: call void @"??YLoadableIntWrapper@@QEAA?AU0@U0@@Z"(ptr {{.*}}, ptr {{.*}} sret(%TSo18LoadableIntWrapperV) %[[OPRESULT]], i32
+// CHECK-aarch64: call void @"??YLoadableIntWrapper@@QEAA?AU0@U0@@Z"(ptr {{.*}}, ptr {{.*}} sret(%TSo18LoadableIntWrapperV) %[[OPRESULT]], i64

test/Interop/Cxx/operators/member-inline-irgen.swift

@@ -5,7 +5,7 @@ import MemberInline
 public func sub(_ lhs: inout LoadableIntWrapper, _ rhs: LoadableIntWrapper) -> LoadableIntWrapper { lhs - rhs }
 
 // CHECK-SYSV: call [[RESA:i32|i64]] [[NAMEA:@_ZN18LoadableIntWrappermiES_]](ptr {{%[0-9]+}}, {{i32|\[1 x i32\]|i64|%struct.LoadableIntWrapper\* byval\(.*\) align 4}} {{%[0-9]+}})
-// CHECK-WIN: call [[RESA:void]] [[NAMEA:@"\?\?GLoadableIntWrapper@@QEAA\?AU0@U0@@Z"]](ptr {{%[0-9]+}}, ptr sret(%struct.LoadableIntWrapper) {{.*}}, i32 {{%[0-9]+}})
+// CHECK-WIN: call [[RESA:void]] [[NAMEA:@"\?\?GLoadableIntWrapper@@QEAA\?AU0@U0@@Z"]](ptr {{%[0-9]+}}, ptr {{.*}} sret(%TSo18LoadableIntWrapperV) {{.*}}, i32 {{%[0-9]+}})
 
 public func call(_ wrapper: inout LoadableIntWrapper, _ arg: Int32) -> Int32 { wrapper(arg) }
 

test/Interop/Cxx/operators/member-out-of-line-irgen.swift

@@ -7,5 +7,5 @@ public func add(_ lhs: inout LoadableIntWrapper, _ rhs: LoadableIntWrapper) -> L
 // CHECK-SYSV: call {{i32|i64}} [[NAME:@_ZNK18LoadableIntWrapperplES_]](ptr %{{[0-9]+}}, {{i32|\[1 x i32\]|i64|%struct.LoadableIntWrapper\* byval\(.*\)}}{{.*}})
 // CHECK-SYSV: declare {{.*}}{{i32|i64}} [[NAME]](ptr {{.*}}, {{i32|\[1 x i32\]|i64|%struct.LoadableIntWrapper\* .*byval\(%struct.LoadableIntWrapper\)}}{{.*}})
 
-// CHECK-WIN: call void [[NAME:@"\?\?HLoadableIntWrapper@@QEBA\?AU0@U0@@Z"]](ptr %{{[0-9]+}}, ptr sret(%struct.LoadableIntWrapper) {{.*}}, i32 %{{[0-9]+}})
+// CHECK-WIN: call void [[NAME:@"\?\?HLoadableIntWrapper@@QEBA\?AU0@U0@@Z"]](ptr %{{[0-9]+}}, ptr {{.*}} sret(%TSo18LoadableIntWrapperV) {{.*}}, i32 %{{[0-9]+}})
 // CHECK-WIN: declare dso_local void [[NAME]](ptr {{.*}}, ptr sret(%struct.LoadableIntWrapper) {{.*}}, i32)