[llvm] [MC,COFF] .safeseh: avoid changeSection (PR #132624)

[Fangrui Song via llvm-commits]

https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/132624

The directive temporarily switches to the .sxdata section to emit data,
and then calls `insert`, which makes `CurFrag` out of sync of the
current section. Call push/switch/pop instead.

Related to #132464


>From 5d8329b81e54e511ac1c18484fbfbdec22f70f9a Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Sun, 23 Mar 2025 10:32:04 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
 =?UTF-8?q?l=20version?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Created using spr 1.3.5-bogner
---
 llvm/lib/MC/MCWinCOFFStreamer.cpp | 4 +++-
 llvm/test/CodeGen/X86/win32-eh.ll | 9 +++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/MC/MCWinCOFFStreamer.cpp b/llvm/lib/MC/MCWinCOFFStreamer.cpp
index d406bc58ccf9d..5d84546b0c175 100644
--- a/llvm/lib/MC/MCWinCOFFStreamer.cpp
+++ b/llvm/lib/MC/MCWinCOFFStreamer.cpp
@@ -287,7 +287,8 @@ void MCWinCOFFStreamer::emitCOFFSafeSEH(MCSymbol const *Symbol) {
     return;
 
   MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
-  changeSection(SXData);
+  pushSection();
+  switchSection(SXData);
   SXData->ensureMinAlignment(Align(4));
 
   insert(getContext().allocFragment<MCSymbolIdFragment>(Symbol));
@@ -298,6 +299,7 @@ void MCWinCOFFStreamer::emitCOFFSafeSEH(MCSymbol const *Symbol) {
   // function. Go ahead and oblige it here.
   CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
                    << COFF::SCT_COMPLEX_TYPE_SHIFT);
+  popSection();
 }
 
 void MCWinCOFFStreamer::emitCOFFSymbolIndex(MCSymbol const *Symbol) {
diff --git a/llvm/test/CodeGen/X86/win32-eh.ll b/llvm/test/CodeGen/X86/win32-eh.ll
index 82dc4beaf972b..d3d19ede546d6 100644
--- a/llvm/test/CodeGen/X86/win32-eh.ll
+++ b/llvm/test/CodeGen/X86/win32-eh.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -mtriple=i686-pc-windows-msvc < %s | FileCheck %s
+; RUN: llc -mtriple=i686-pc-windows-msvc -filetype=obj < %s -o %t
 
 declare void @may_throw_or_crash()
 declare i32 @_except_handler3(...)
@@ -208,6 +209,14 @@ catch:
 ; CHECK-NEXT:  .long   0
 ; CHECK-NEXT:  .long   1
 
+; CHECK-LABEL: inlineasm:
+; CHECK: .safeseh my_handler
+define i32 @inlineasm() {
+entry:
+  call void asm sideeffect ".safeseh my_handler", "~{dirflag},~{fpsr},~{flags}"()
+  ret i32 0
+}
+
 ; CHECK-LABEL: ___ehhandler$use_CxxFrameHandler3:
 ; CHECK: movl $L__ehtable$use_CxxFrameHandler3, %eax
 ; CHECK-NEXT: jmp  ___CxxFrameHandler3 # TAILCALL