[clang] [WinEH] Fix crash when aligning parameters larger than ABI (PR #180905)

[via cfe-commits]

https://github.com/GkvJwa updated https://github.com/llvm/llvm-project/pull/180905

>From 416ca75e0cb5337995a7546878ab6c9f0a9815c1 Mon Sep 17 00:00:00 2001
From: GkvJwa <gkvjwa at gmail.com>
Date: Mon, 2 Mar 2026 17:50:03 +0800
Subject: [PATCH] [WinEH] Fix crash when aligning parameters larger than ABI

---
 clang/lib/CodeGen/CGException.cpp             | 30 ++++++++++----
 .../windows-seh-arg-capture-crash.cpp.cpp     | 39 +++++++++++++++++++
 2 files changed, 62 insertions(+), 7 deletions(-)
 create mode 100644 clang/test/CodeGen/windows-seh-arg-capture-crash.cpp.cpp

diff --git a/clang/lib/CodeGen/CGException.cpp b/clang/lib/CodeGen/CGException.cpp
index 2f1df6e9a8a5c..fb96ede7a6812 100644
--- a/clang/lib/CodeGen/CGException.cpp
+++ b/clang/lib/CodeGen/CGException.cpp
@@ -1834,10 +1834,23 @@ struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
 Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
                                                    Address ParentVar,
                                                    llvm::Value *ParentFP) {
-  llvm::CallInst *RecoverCall = nullptr;
+  llvm::Value *RecoverCall = nullptr;
   CGBuilderTy Builder(*this, AllocaInsertPt);
-  if (auto *ParentAlloca =
-          dyn_cast_or_null<llvm::AllocaInst>(ParentVar.getBasePointer())) {
+  auto *ParentAlloca =
+      dyn_cast_or_null<llvm::AllocaInst>(ParentVar.getBasePointer());
+  auto *ParentArg =
+      dyn_cast_or_null<llvm::Argument>(ParentVar.getBasePointer());
+  if (!ParentAlloca) {
+    if (ParentArg) {
+      llvm::BasicBlock &EntryBB = ParentCGF.CurFn->getEntryBlock();
+      llvm::IRBuilder<> ParentEntryBuilder(&EntryBB, EntryBB.begin());
+      ParentAlloca = ParentEntryBuilder.CreateAlloca(
+          ParentArg->getType(), nullptr, ParentArg->getName() + ".addr");
+      ParentEntryBuilder.CreateStore(ParentArg, ParentAlloca);
+    }
+  }
+
+  if (ParentAlloca) {
     // Mark the variable escaped if nobody else referenced it and compute the
     // localescape index.
     auto InsertPair = ParentCGF.EscapedLocals.insert(
@@ -1849,7 +1862,9 @@ Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
     RecoverCall = Builder.CreateCall(
         FrameRecoverFn, {ParentCGF.CurFn, ParentFP,
                          llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx)});
-
+    if (ParentArg)
+      RecoverCall = Builder.CreateLoad(
+          Address(RecoverCall, ParentArg->getType(), getPointerAlign()));
   } else {
     // If the parent didn't have an alloca, we're doing some nested outlining.
     // Just clone the existing localrecover call, but tweak the FP argument to
@@ -1858,9 +1873,10 @@ Address CodeGenFunction::recoverAddrOfEscapedLocal(CodeGenFunction &ParentCGF,
         ParentVar.emitRawPointer(*this)->stripPointerCasts());
     assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::localrecover &&
            "expected alloca or localrecover in parent LocalDeclMap");
-    RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
-    RecoverCall->setArgOperand(1, ParentFP);
-    RecoverCall->insertBefore(AllocaInsertPt->getIterator());
+    RecoverCall = ParentRecover->clone();
+    cast<llvm::CallInst>(RecoverCall)->setArgOperand(1, ParentFP);
+    cast<llvm::CallInst>(RecoverCall)
+        ->insertBefore(AllocaInsertPt->getIterator());
   }
 
   // Bitcast the variable, rename it, and insert it in the local decl map.
diff --git a/clang/test/CodeGen/windows-seh-arg-capture-crash.cpp.cpp b/clang/test/CodeGen/windows-seh-arg-capture-crash.cpp.cpp
new file mode 100644
index 0000000000000..d985e3320b340
--- /dev/null
+++ b/clang/test/CodeGen/windows-seh-arg-capture-crash.cpp.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -fms-extensions -fexceptions -emit-llvm -o - %s | FileCheck %s
+
+class span_a {
+  public:
+    char data_;
+    int size_;
+};
+
+long g(span_a input);
+
+void f(span_a input) {
+  __try {
+  } __except (g(input)) {
+  }
+}
+
+// CHECK-LABEL: define dso_local void @"?f@@YAXVspan_a@@@Z"(i64 %input.coerce)
+// CHECK: entry:
+// CHECK:   call void (...) @llvm.localescape(ptr %input)
+
+typedef __SIZE_TYPE__ size_t;
+
+class span_b {
+public:
+  char data_;
+  size_t size_;
+};
+
+long g(span_b input);
+
+void f(span_b input) {
+  __try {
+  } __except (g(input)) {
+  }
+}
+
+// CHECK-LABEL: define dso_local void @"?f@@YAXVspan_b@@@Z"(ptr noundef dead_on_return %input)
+// CHECK: entry:
+// CHECK:   call void (...) @llvm.localescape(ptr %input.addr)
\ No newline at end of file