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Porting LLVM

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Lucas Holt edited this page Mar 27, 2025 · 6 revisions

LLVM Changes

This page is a place to document changes needed to get LLVM running.

Ideally, we'd get a correct upstream patchset to LLVM. That was tried around the LLVM 6/7 era and rejected. (We should try again at some point)

MidnightBSD src patches

MidnightBSD (current 4.0) LLVM 18?

patch 1 patch 2 patch 3 patch 4 patch 5 patch 6 patch 7 patch 8 (LLDB) patch 9 patch 10 ...

mports

clang

These are 'hacks' to get the FreeBSD target to work, not the proper way to do this.

clang/lib/Basic/Targets/OSTargets.h

In the FreeBSD target, we do a hack to get __MidnightBSD__ and __MidnightBSD_cc_version defined

#ifndef MIDNIGHTBSD_CC_VERSION
 #define MIDNIGHTBSD_CC_VERSION 0U
 #endif
 
               // FreeBSD Target
template <typename Target>
class LLVM_LIBRARY_VISIBILITY FreeBSDTargetInfo : public OSTargetInfo<Target> {
protected:
  void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
                    MacroBuilder &Builder) const override {
    // FreeBSD defines; list based off of gcc output

    unsigned Release = Triple.getOSMajorVersion();
    if (Release == 0U)
      Release = 8U;
    unsigned CCVersion = MIDNIGHTBSD_CC_VERSION;
    if (CCVersion == 0U)
      CCVersion = Release * 100000U + 1U;

    Builder.defineMacro("__MidnightBSD__", Twine(Release));
    Builder.defineMacro("__MidnightBSD_cc_version", Twine(CCVersion));
    // freebsd compatibility
    Builder.defineMacro("__FreeBSD__", Twine(13U));
    Builder.defineMacro("__FreeBSD_cc_version", Twine(CCVersion));
    Builder.defineMacro("__KPRINTF_ATTRIBUTE__");
    DefineStd(Builder, "unix", Opts);
    if (this->HasFloat128)
      Builder.defineMacro("__FLOAT128__");

See Also

LLVM Hacks for building things

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