JIT: Support loading Swift self register from SwiftSelf struct (#99132)

Adds JIT support for loading the Swift self/context register value from the SwiftSelf struct argument passed to a Swift call. Also enables corresponding tests.

src/coreclr/jit/compiler.h

@@ -4367,7 +4367,7 @@ class Compiler
     void impCheckForPInvokeCall(
         GenTreeCall* call, CORINFO_METHOD_HANDLE methHnd, CORINFO_SIG_INFO* sig, unsigned mflags, BasicBlock* block);
     GenTreeCall* impImportIndirectCall(CORINFO_SIG_INFO* sig, const DebugInfo& di = DebugInfo());
-    void impPopArgsForUnmanagedCall(GenTreeCall* call, CORINFO_SIG_INFO* sig, /* OUT */ CallArg** swiftErrorArg, /* OUT */ CallArg** swiftSelfArg);
+    void impPopArgsForUnmanagedCall(GenTreeCall* call, CORINFO_SIG_INFO* sig, /* OUT */ CallArg** swiftErrorArg);
 
 #ifdef SWIFT_SUPPORT
     void impAppendSwiftErrorStore(GenTreeCall* call, CallArg* const swiftErrorArg);

src/coreclr/jit/gentree.cpp

@@ -1843,6 +1843,13 @@ regNumber CallArgs::GetCustomRegister(Compiler* comp, CorInfoCallConvExtension c
         case WellKnownArg::DispatchIndirectCallTarget:
             return REG_DISPATCH_INDIRECT_CALL_ADDR;
 #endif
+
+#ifdef SWIFT_SUPPORT
+        case WellKnownArg::SwiftSelf:
+            assert(cc == CorInfoCallConvExtension::Swift);
+            return REG_SWIFT_SELF;
+#endif // SWIFT_SUPPORT
+
         default:
             break;
     }
@@ -13092,6 +13099,8 @@ const char* Compiler::gtGetWellKnownArgNameForArgMsg(WellKnownArg arg)
         case WellKnownArg::ValidateIndirectCallTarget:
         case WellKnownArg::DispatchIndirectCallTarget:
             return "cfg tgt";
+        case WellKnownArg::SwiftSelf:
+            return "swift self";
         default:
             return nullptr;
     }

src/coreclr/jit/gentree.h

@@ -4401,7 +4401,7 @@ enum class CFGCallKind
 
 class CallArgs;
 
-enum class WellKnownArg
+enum class WellKnownArg : unsigned
 {
     None,
     ThisPointer,
@@ -4419,6 +4419,7 @@ enum class WellKnownArg
     R2RIndirectionCell,
     ValidateIndirectCallTarget,
     DispatchIndirectCallTarget,
+    SwiftSelf,
 };
 
 #ifdef DEBUG
@@ -4728,6 +4729,7 @@ class CallArg
     CORINFO_CLASS_HANDLE GetSignatureClassHandle() { return m_signatureClsHnd; }
     var_types GetSignatureType() { return m_signatureType; }
     WellKnownArg GetWellKnownArg() { return m_wellKnownArg; }
+    void SetWellKnownArg(const WellKnownArg argType) { m_wellKnownArg = argType; }
     bool IsTemp() { return m_isTmp; }
     // clang-format on
 

src/coreclr/jit/importercalls.cpp

@@ -98,10 +98,9 @@ var_types Compiler::impImportCall(OPCODE                  opcode,
     CORINFO_SIG_INFO calliSig;
     NewCallArg       extraArg;
 
-    // Swift calls may use special register types that require additional IR to handle,
-    // so if we're importing a Swift call, look for these types in the signature
+    // Swift calls that might throw use a SwiftError* arg that requires additional IR to handle,
+    // so if we're importing a Swift call, look for this type in the signature
     CallArg* swiftErrorArg = nullptr;
-    CallArg* swiftSelfArg  = nullptr;
 
     /*-------------------------------------------------------------------------
      * First create the call node
@@ -670,7 +669,7 @@ var_types Compiler::impImportCall(OPCODE                  opcode,
 
         checkForSmallType = true;
 
-        impPopArgsForUnmanagedCall(call->AsCall(), sig, &swiftErrorArg, &swiftSelfArg);
+        impPopArgsForUnmanagedCall(call->AsCall(), sig, &swiftErrorArg);
 
         goto DONE;
     }
@@ -1840,8 +1839,7 @@ GenTreeCall* Compiler::impImportIndirectCall(CORINFO_SIG_INFO* sig, const DebugI
 
 void Compiler::impPopArgsForUnmanagedCall(GenTreeCall*        call,
                                           CORINFO_SIG_INFO*   sig,
-                                          /* OUT */ CallArg** swiftErrorArg,
-                                          /* OUT */ CallArg** swiftSelfArg)
+                                          /* OUT */ CallArg** swiftErrorArg)
 {
     assert(call->gtFlags & GTF_CALL_UNMANAGED);
 
@@ -1867,6 +1865,7 @@ void Compiler::impPopArgsForUnmanagedCall(GenTreeCall*        call,
 
 #ifdef SWIFT_SUPPORT
     unsigned short swiftErrorIndex = sig->numArgs;
+    unsigned short swiftSelfIndex  = sig->numArgs;
 
     // We are importing an unmanaged Swift call, which might require special parameter handling
     if (call->unmgdCallConv == CorInfoCallConvExtension::Swift)
@@ -1915,13 +1914,29 @@ void Compiler::impPopArgsForUnmanagedCall(GenTreeCall*        call,
                 swiftErrorIndex  = argIndex;
                 checkEntireStack = true;
             }
-            // TODO: Handle SwiftSelf, SwiftAsync
+            else if ((strcmp(className, "SwiftSelf") == 0) &&
+                     (strcmp(namespaceName, "System.Runtime.InteropServices.Swift") == 0))
+            {
+                // We expect a SwiftSelf struct to be passed, not a pointer/reference
+                if (argIsByrefOrPtr)
+                {
+                    BADCODE("Expected SwiftSelf struct, got pointer/reference");
+                }
+
+                if (swiftSelfIndex != sig->numArgs)
+                {
+                    BADCODE("Duplicate SwiftSelf parameter");
+                }
+
+                swiftSelfIndex = argIndex;
+            }
+            // TODO: Handle SwiftAsync
         }
 
         // Don't need to reverse args for Swift calls
         argsToReverse = 0;
 
-        // If using one of the Swift register types, check entire stack for side effects
+        // If using SwiftError*, check entire stack for side effects
         if (checkEntireStack)
         {
             impSpillSideEffects(true, CHECK_SPILL_ALL DEBUGARG("Spill for swift calls"));
@@ -2006,7 +2021,12 @@ void Compiler::impPopArgsForUnmanagedCall(GenTreeCall*        call,
             assert(swiftErrorArg != nullptr);
             *swiftErrorArg = &arg;
         }
-// TODO: SwiftSelf, SwiftAsync
+        else if (argIndex == swiftSelfIndex)
+        {
+            // Found the SwiftSelf arg
+            arg.SetWellKnownArg(WellKnownArg::SwiftSelf);
+        }
+// TODO: SwiftAsync
 #endif // SWIFT_SUPPORT
 
         argIndex++;

src/coreclr/jit/morph.cpp

@@ -765,6 +765,8 @@ const char* getWellKnownArgName(WellKnownArg arg)
             return "ValidateIndirectCallTarget";
         case WellKnownArg::DispatchIndirectCallTarget:
             return "DispatchIndirectCallTarget";
+        case WellKnownArg::SwiftSelf:
+            return "SwiftSelf";
     }
 
     return "N/A";
@@ -3179,7 +3181,9 @@ GenTreeCall* Compiler::fgMorphArgs(GenTreeCall* call)
         }
 
         // TODO-ARGS: Review this, is it really necessary to treat them specially here?
-        if (call->gtArgs.IsNonStandard(this, call, &arg) && arg.AbiInfo.IsPassedInRegisters())
+        // Exception: Lower SwiftSelf struct arg to GT_LCL_FLD
+        if (call->gtArgs.IsNonStandard(this, call, &arg) && arg.AbiInfo.IsPassedInRegisters() &&
+            (arg.GetWellKnownArg() != WellKnownArg::SwiftSelf))
         {
             flagsSummary |= argx->gtFlags;
             continue;

src/coreclr/jit/targetamd64.h

@@ -566,6 +566,6 @@
   #define SWIFT_SUPPORT
   #define REG_SWIFT_ERROR REG_R12
   #define RBM_SWIFT_ERROR RBM_R12
-  #define SWIFT_SELF_REG  REG_R13
+  #define REG_SWIFT_SELF  REG_R13
 
 // clang-format on

src/coreclr/jit/targetarm64.h

@@ -373,6 +373,6 @@
   #define SWIFT_SUPPORT
   #define REG_SWIFT_ERROR REG_R21
   #define RBM_SWIFT_ERROR RBM_R21
-  #define SWIFT_SELF_REG  REG_R20
+  #define REG_SWIFT_SELF  REG_R20
 
 // clang-format on

src/tests/Interop/Swift/SwiftSelfContext/SwiftSelfContext.csproj

@@ -5,8 +5,6 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <!-- Swift interop is supported on Apple platforms only -->
     <CLRTestTargetUnsupported Condition="'$(TargetsOSX)' != 'true' and '$(TargetsAppleMobile)' != 'true'">true</CLRTestTargetUnsupported>
-    <!-- Tracking issue: https://github.com/dotnet/runtime/issues/93631 -->
-    <CLRTestTargetUnsupported Condition="'$(RuntimeFlavor)' != 'mono'">true</CLRTestTargetUnsupported>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(MSBuildProjectName).cs" />

src/tests/issues.targets

@@ -78,9 +78,6 @@
         <ExcludeList Include="$(XunitTestBinBase)/Interop/Swift/SwiftInvalidCallConv/*">
             <Issue>https://github.com/dotnet/runtime/issues/93631</Issue>
         </ExcludeList>
-        <ExcludeList Include="$(XunitTestBinBase)/Interop/Swift/SwiftSelfContext/*">
-            <Issue>https://github.com/dotnet/runtime/issues/93631</Issue>
-        </ExcludeList>
     </ItemGroup>
 
     <!-- All Unix targets on all runtimes -->