[llvm] [LTT] mark the CFI jumptable naked on Windows (PR #170371)

[Mircea Trofin via llvm-commits]

https://github.com/mtrofin updated https://github.com/llvm/llvm-project/pull/170371

>From fe3a86e85bd223cf418fa41d64fcb83406970579 Mon Sep 17 00:00:00 2001
From: Mircea Trofin <mtrofin at google.com>
Date: Tue, 2 Dec 2025 13:48:10 -0800
Subject: [PATCH] [LLT] mark the CFI jumptable naked on Windows

---
 llvm/lib/Transforms/IPO/LowerTypeTests.cpp      |  7 +------
 llvm/test/Transforms/LowerTypeTests/function.ll | 11 +++++------
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
index fa35eef2c00f5..f7aeda95e41b3 100644
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -1554,12 +1554,7 @@ void LowerTypeTestsModule::createJumpTable(
 
   // Align the whole table by entry size.
   F->setAlignment(Align(getJumpTableEntrySize(JumpTableArch)));
-  // Skip prologue.
-  // Disabled on win32 due to https://llvm.org/bugs/show_bug.cgi?id=28641#c3.
-  // Luckily, this function does not get any prologue even without the
-  // attribute.
-  if (OS != Triple::Win32)
-    F->addFnAttr(Attribute::Naked);
+  F->addFnAttr(Attribute::Naked);
   if (JumpTableArch == Triple::arm)
     F->addFnAttr("target-features", "-thumb-mode");
   if (JumpTableArch == Triple::thumb) {
diff --git a/llvm/test/Transforms/LowerTypeTests/function.ll b/llvm/test/Transforms/LowerTypeTests/function.ll
index ab3cfb6acccf8..fa7c7bbcdabd3 100644
--- a/llvm/test/Transforms/LowerTypeTests/function.ll
+++ b/llvm/test/Transforms/LowerTypeTests/function.ll
@@ -1,7 +1,7 @@
-; RUN: opt -S -passes=lowertypetests -mtriple=i686-unknown-linux-gnu %s | FileCheck --check-prefixes=X86,X86-LINUX,NATIVE,JT8 %s
-; RUN: opt -S -passes=lowertypetests -mtriple=x86_64-unknown-linux-gnu %s | FileCheck --check-prefixes=X86,X86-LINUX,NATIVE,JT8 %s
-; RUN: opt -S -passes=lowertypetests -mtriple=i686-pc-win32 %s | FileCheck --check-prefixes=X86,X86-WIN32,NATIVE,JT8 %s
-; RUN: opt -S -passes=lowertypetests -mtriple=x86_64-pc-win32 %s | FileCheck --check-prefixes=X86,X86-WIN32,NATIVE,JT8 %s
+; RUN: opt -S -passes=lowertypetests -mtriple=i686-unknown-linux-gnu %s | FileCheck --check-prefixes=X86,NATIVE,JT8 %s
+; RUN: opt -S -passes=lowertypetests -mtriple=x86_64-unknown-linux-gnu %s | FileCheck --check-prefixes=X86,NATIVE,JT8 %s
+; RUN: opt -S -passes=lowertypetests -mtriple=i686-pc-win32 %s | FileCheck --check-prefixes=X86,NATIVE,JT8 %s
+; RUN: opt -S -passes=lowertypetests -mtriple=x86_64-pc-win32 %s | FileCheck --check-prefixes=X86,NATIVE,JT8 %s
 ; RUN: opt -S -passes=lowertypetests -mtriple=riscv32-unknown-linux-gnu %s | FileCheck --check-prefixes=RISCV,NATIVE,JT8 %s
 ; RUN: opt -S -passes=lowertypetests -mtriple=riscv64-unknown-linux-gnu %s | FileCheck --check-prefixes=RISCV,NATIVE,JT8 %s
 ; RUN: opt -S -passes=lowertypetests -mtriple=wasm32-unknown-unknown %s | FileCheck --check-prefix=WASM32 %s
@@ -114,8 +114,7 @@ define i1 @foo(ptr %p) {
 
 ; NATIVE-SAME: "s"(ptr @g.cfi)
 
-; X86-LINUX: attributes #[[ATTR]] = { naked nocf_check noinline }
-; X86-WIN32: attributes #[[ATTR]] = { nocf_check noinline }
+; X86: attributes #[[ATTR]] = { naked nocf_check noinline }
 ; ARM: attributes #[[ATTR]] = { naked noinline
 ; THUMB: attributes #[[ATTR]] = { naked noinline "target-cpu"="cortex-a8" "target-features"="+thumb-mode" }
 ; THUMBV6M: attributes #[[ATTR]] = { naked noinline "target-features"="+thumb-mode" }