[cfe][M68k] (Patch 7/8) Basic Clang support

[myhsu]

Summary

1. Add M68k as new Clang target
2. Add new attribute to support M68k's ISR (Interrupt Service Routine)

[myhsu]

Fix formatting issues

[myhsu]

Update licenses

[myhsu]

Fix the CPU name passing to the backend. Also removed M68060 for now, since backend hasn't fully implemented it yet.

[myhsu]

[NFC] Rename M680x0 to M68k

[rengolin]

clang/lib/Basic/Targets.cpp

314

No support for bare-metal?

clang/lib/Basic/Targets/M68k.cpp

124

no "sp", "pc", etc? Or are all of them aliased to those?

clang/lib/CodeGen/TargetInfo.cpp

8085

That's an odd comment... :)

What doesn't work right now? Something or everything?

[RKSimon]

clang/lib/Basic/CMakeLists.txt

82

(sorting) - move after Le64.cpp

clang/lib/CodeGen/TargetInfo.cpp

8089

(style) Use const auto * for cast results

[bruno]

Looking forward to see m68k support (and hopefully sega genesis toolchain support someday)!

clang/lib/Basic/Targets/M68k.cpp

74

This doesn't seem to match the coding style, clang-format to the rescue.

90

Can you make all the defineMacro inline within the cases? Clarity seems more useful here.

clang/lib/Basic/Targets/M68k.h

36

Can you remove the comment and add the enum back whenever you introduce CK_68060 support?

[myhsu]

• Rebased to latest changes
• Addressed some of the feedbacks

[myhsu]

• Addressed all the feedbacks
• Fixed minor issues that would retrieve the wrong TargetCodeGenInfo instance

clang/lib/Basic/Targets.cpp

314

currently we don't have any plan for that

clang/lib/Basic/Targets/M68k.cpp

124

stack pointer is aliased to a7, but I'll add pc into the list.

clang/lib/CodeGen/TargetInfo.cpp

8085

Seems to work after I fixed a minor issue in getting the correct TargetCodeGenInfo. Will remove this comment.

[rengolin]

Thanks for the changes. This looks good to me but I'll let others check again and approve.

[myhsu]

• Add support for M68060 sub-target

[bruno]

LGTM

[RKSimon]

clang/lib/Basic/Targets/M68k.h

14

@myhsu This should probably be LLVM_CLANG_LIB_BASIC_TARGETS_M68K_H

[jrtc27]

clang/lib/Basic/Targets/M68k.cpp

38–50

If we're in SysV psABI land, then the stack is 32-bit aligned.

If we're in actual ABI used by everyone out there, i.e. GCC's default, then it's only 16-bit aligned, and your integer types also have the wrong alignment, so you will get ABI incompatibility with GCC-built binaries as provided by distributions like Debian.

63

GCC's -mcpu excludes any M prefix and is just the number.

77–79

Where are these coming from? GCC only defines __m68k__.