[clang] [clang] Add Swift support for MIPS (PR #205461)

[Alsey Coleman Miller via cfe-commits]

https://github.com/colemancda created https://github.com/llvm/llvm-project/pull/205461

Adds support for compiling Swift targeting the MIPS ABI.

Related to https://github.com/swiftlang/swift/issues/58204

>From 7f8304924a20b5c0fb2bb861b02633632308bdd9 Mon Sep 17 00:00:00 2001
From: Alsey Coleman Miller <alseycmiller at gmail.com>
Date: Tue, 23 Jun 2026 20:50:46 -0400
Subject: [PATCH] [clang] Add Swift support for MIPS

Adds support for compiling Swift targeting the MIPS ABI
---
 clang/lib/Basic/Targets/Mips.h     | 11 +++++++++++
 clang/lib/CodeGen/Targets/Mips.cpp |  5 ++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Basic/Targets/Mips.h b/clang/lib/Basic/Targets/Mips.h
index 2f251c7eb8690..ebdd7d083709b 100644
--- a/clang/lib/Basic/Targets/Mips.h
+++ b/clang/lib/Basic/Targets/Mips.h
@@ -433,6 +433,17 @@ class LLVM_LIBRARY_VISIBILITY MipsTargetInfo : public TargetInfo {
   std::pair<unsigned, unsigned> hardwareInterferenceSizes() const override {
     return std::make_pair(32, 32);
   }
+
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_Swift:
+      return CCCR_OK;
+    case CC_SwiftAsync:
+      return CCCR_Error;
+    default:
+      return CCCR_Warning;
+    }
+  }
 };
 
 class LLVM_LIBRARY_VISIBILITY WindowsMipsTargetInfo
diff --git a/clang/lib/CodeGen/Targets/Mips.cpp b/clang/lib/CodeGen/Targets/Mips.cpp
index 22fdcd95ea8fa..3693e5dbfa91c 100644
--- a/clang/lib/CodeGen/Targets/Mips.cpp
+++ b/clang/lib/CodeGen/Targets/Mips.cpp
@@ -44,7 +44,10 @@ class MIPSTargetCodeGenInfo : public TargetCodeGenInfo {
 public:
   MIPSTargetCodeGenInfo(CodeGenTypes &CGT, bool IsO32)
       : TargetCodeGenInfo(std::make_unique<MipsABIInfo>(CGT, IsO32)),
-        SizeOfUnwindException(IsO32 ? 24 : 32) {}
+        SizeOfUnwindException(IsO32 ? 24 : 32) {
+    SwiftInfo =
+        std::make_unique<SwiftABIInfo>(CGT, /*SwiftErrorInRegister=*/false);
+  }
 
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &CGM) const override {
     return 29;