[Cygwin] Cygwin cmodel medium for 64 bit

[xu-chiheng]

Cygwin 64 bit must use cmodel medium .

I have build scripts and patches at https://github.com/xu-chiheng/Note .
I can use the build scripts and patches to build and bootstrap GCC(start from 13.0.0) and Clang/LLVM(start from 16.0.0), using GCC or Clang, on Cygwin and MinGW.
If you have interests, you can look at my other PRs at https://github.com/llvm/llvm-project/pulls/xu-chiheng .

Most patches come from upstream at

https://cygwin.com/git-cygwin-packages/
https://cygwin.com/git-cygwin-packages/?p=git/cygwin-packages/clang.git;a=summary
git://cygwin.com/git/cygwin-packages/clang.git
https://cygwin.com/git-cygwin-packages/?p=git/cygwin-packages/llvm.git;a=summary
git://cygwin.com/git/cygwin-packages/llvm.git

https://github.com/msys2/MINGW-packages/tree/master/mingw-w64-clang
https://github.com/msys2/MINGW-packages/blob/master/mingw-w64-clang/PKGBUILD

https://src.fedoraproject.org/rpms/llvm.git

[llvmbot]

@llvm/pr-subscribers-backend-x86

Author: 徐持恒 Xu Chiheng (xu-chiheng)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/74931.diff

1 Files Affected:

• (modified) llvm/lib/Target/X86/X86TargetMachine.cpp (+5-3)

diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index 5668b514d6dec0..544b88228d5614 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -206,8 +206,8 @@ static Reloc::Model getEffectiveRelocModel(const Triple &TT, bool JIT,
 }
 
 static CodeModel::Model
-getEffectiveX86CodeModel(std::optional<CodeModel::Model> CM, bool JIT,
-                         bool Is64Bit) {
+getEffectiveX86CodeModel(const Triple &TT, std::optional<CodeModel::Model> CM, bool JIT) {
+  bool Is64Bit = TT.getArch() == Triple::x86_64;
   if (CM) {
     if (*CM == CodeModel::Tiny)
       report_fatal_error("Target does not support the tiny CodeModel", false);
@@ -215,6 +215,8 @@ getEffectiveX86CodeModel(std::optional<CodeModel::Model> CM, bool JIT,
   }
   if (JIT)
     return Is64Bit ? CodeModel::Large : CodeModel::Small;
+  if (TT.isWindowsCygwinEnvironment())
+    return Is64Bit ? CodeModel::Medium : CodeModel::Small;
   return CodeModel::Small;
 }
 
@@ -229,7 +231,7 @@ X86TargetMachine::X86TargetMachine(const Target &T, const Triple &TT,
     : LLVMTargetMachine(
           T, computeDataLayout(TT), TT, CPU, FS, Options,
           getEffectiveRelocModel(TT, JIT, RM),
-          getEffectiveX86CodeModel(CM, JIT, TT.getArch() == Triple::x86_64),
+          getEffectiveX86CodeModel(TT, CM, JIT),
           OL),
       TLOF(createTLOF(getTargetTriple())), IsJIT(JIT) {
   // On PS4/PS5, the "return address" of a 'noreturn' call must still be within

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[asl]

This lacks tests and proper description

[xu-chiheng]

This lacks tests and proper description

Cygwin 64 bit must use cmodel medium. Other wise Clang can't bootstrap.

I have build scripts and patches at https://github.com/xu-chiheng/Note

Cygwin also have outdated patches at :
https://cygwin.com/git-cygwin-packages/
https://cygwin.com/git-cygwin-packages/?p=git/cygwin-packages/clang.git;a=summary
git://cygwin.com/git/cygwin-packages/clang.git
https://cygwin.com/git-cygwin-packages/?p=git/cygwin-packages/llvm.git;a=summary
git://cygwin.com/git/cygwin-packages/llvm.git