From cd4385dc3975bd51ec6b53c8aca765411f186927 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Martin=20Storsj=C3=B6?= Date: Wed, 8 Oct 2025 14:55:23 +0300 Subject: [PATCH] [clang] Fix catching pointers by reference on mingw targets For this specific case, when catching a pointer data type, by reference, Clang generates a special code pattern, which directly accesses the exception data by skipping past the `_Unwind_Exception` manually (rather than using the return value of `__cxa_begin_catch`). On most platforms, `_Unwind_Exception` is 32 bytes, but in some configurations it's different. (ARM EHABI is one preexisting case.) In the case of SEH, it's also different - it is 48 bytes in 32 bit mode and 64 bytes in 64 bit mode. Handle this case in `TargetCodeGenInfo::getSizeOfUnwindException`, fixing the code generation for catching pointers by reference. This fixes https://github.com/mstorsjo/llvm-mingw/issues/522. --- clang/lib/CodeGen/TargetInfo.cpp | 2 ++ clang/test/CodeGenCXX/sizeof-unwind-exception.cpp | 8 ++++++++ 2 files changed, 10 insertions(+) diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp index 1e58c3f217812..342a3af0ac1ee 100644 --- a/clang/lib/CodeGen/TargetInfo.cpp +++ b/clang/lib/CodeGen/TargetInfo.cpp @@ -82,6 +82,8 @@ TargetCodeGenInfo::~TargetCodeGenInfo() = default; // If someone can figure out a general rule for this, that would be great. // It's probably just doomed to be platform-dependent, though. unsigned TargetCodeGenInfo::getSizeOfUnwindException() const { + if (getABIInfo().getCodeGenOpts().hasSEHExceptions()) + return getABIInfo().getDataLayout().getPointerSizeInBits() > 32 ? 64 : 48; // Verified for: // x86-64 FreeBSD, Linux, Darwin // x86-32 FreeBSD, Linux, Darwin diff --git a/clang/test/CodeGenCXX/sizeof-unwind-exception.cpp b/clang/test/CodeGenCXX/sizeof-unwind-exception.cpp index 4fb977a5367e7..e40b2d7ae43ea 100644 --- a/clang/test/CodeGenCXX/sizeof-unwind-exception.cpp +++ b/clang/test/CodeGenCXX/sizeof-unwind-exception.cpp @@ -3,6 +3,8 @@ // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fcxx-exceptions -fexceptions %s -O2 -o - | FileCheck %s --check-prefix=ARM-DARWIN // RUN: %clang_cc1 -triple arm-unknown-gnueabi -emit-llvm -fcxx-exceptions -fexceptions %s -O2 -o - | FileCheck %s --check-prefix=ARM-EABI // RUN: %clang_cc1 -triple mipsel-unknown-unknown -emit-llvm -fcxx-exceptions -fexceptions %s -O2 -o - | FileCheck %s --check-prefix=MIPS +// RUN: %clang_cc1 -triple x86_64-windows-gnu -emit-llvm -fcxx-exceptions -fexceptions -exception-model=seh %s -O2 -o - | FileCheck %s --check-prefix=MINGW-X86-64 +// RUN: %clang_cc1 -triple thumbv7-windows-gnu -emit-llvm -fcxx-exceptions -fexceptions -exception-model=seh %s -O2 -o - | FileCheck %s --check-prefix=MINGW-ARMV7 void foo(); void test() { @@ -25,9 +27,15 @@ void test() { // ARM-EABI-NEXT: [[T1:%.*]] = getelementptr i8, ptr [[EXN]], i32 88 // MIPS: [[T0:%.*]] = tail call ptr @__cxa_begin_catch(ptr [[EXN:%.*]]) [[NUW:#[0-9]+]] // MIPS-NEXT: [[T1:%.*]] = getelementptr i8, ptr [[EXN]], i32 24 +// MINGW-X86-64: [[T0:%.*]] = tail call ptr @__cxa_begin_catch(ptr [[EXN:%.*]]) [[NUW:#[0-9]+]] +// MINGW-X86-64-NEXT:[[T1:%.*]] = getelementptr i8, ptr [[EXN]], i64 64 +// MINGW-ARMV7: [[T0:%.*]] = tail call arm_aapcs_vfpcc ptr @__cxa_begin_catch(ptr [[EXN:%.*]]) [[NUW:#[0-9]+]] +// MINGW-ARMV7-NEXT: [[T1:%.*]] = getelementptr i8, ptr [[EXN]], i32 48 // X86-64: attributes [[NUW]] = { nounwind } // X86-32: attributes [[NUW]] = { nounwind } // ARM-DARWIN: attributes [[NUW]] = { nounwind } // ARM-EABI: attributes [[NUW]] = { nounwind } // MIPS: attributes [[NUW]] = { nounwind } +// MINGW-X86-64: attributes [[NUW]] = { nounwind } +// MINGW-ARMV7: attributes [[NUW]] = { nounwind }