Summary:
As I maintain the AVR backend and am currently in the process of migrating it in tree, it makes sense to add myself as the code owner.

Thoughts welcome!

Differential Revision: http://reviews.llvm.org/D14002

llvm-svn: 251471

llvm-svn: 251367

llvm-svn: 246954

llvm-svn: 244823

This WebAssembly backend is just a skeleton at this time and is not yet
functional.

llvm-svn: 241022

llvm-svn: 236540

llvm-svn: 235360

llvm-svn: 232395

llvm-svn: 231412

llvm-svn: 227340

Summary:
V8->V9:
- cleanup tests

V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests

V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)

V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
  46 files changed, 456 insertions(+), 469 deletions(-)

V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense

V3->V4:
- added CODE_OWNERS entry for BPF backend

V2->V3:
- fix metadata in tests

V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin

V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.

The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/

One of use cases: dtrace/systemtap alternative.

bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe

instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt



Short summary of instruction set:
- 64-bit registers
  R0      - return value from in-kernel function, and exit value for BPF program
  R1 - R5 - arguments from BPF program to in-kernel function
  R6 - R9 - callee saved registers that in-kernel function will preserve
  R10     - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd

Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.

It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.

This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.

Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>

Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits

Differential Revision: http://reviews.llvm.org/D6494

llvm-svn: 227008

As agreed with Richard Sandiford, I'm taking over code ownership
for the SystemZ back end from him.

llvm-svn: 224535

llvm-svn: 224088

I apparently fail at the alphabet, E is not after G, and G isn't even
close to C. Sorry for the noise.

llvm-svn: 223990

llvm-svn: 223989

llvm-svn: 223988

llvm-svn: 223691

llvm-svn: 217659

Add one for Greg Clayton, Peter Collingbourne, Tobias Grosser and
Jakob Olesen based on recent commits.

llvm-svn: 214762

As per nominations from Chandler and Arnold.

llvm-svn: 213955

Add myself as the code owner for the scoped-noalias metadata I've developed.

llvm-svn: 213950

llvm-svn: 213302

llvm-svn: 205483

llvm-svn: 203824

llvm-svn: 201573

llvm-svn: 201432

llvm-svn: 196369

llvm-svn: 195915

I am the code owner of the loop reroller.

llvm-svn: 195271

llvm-svn: 194828

Per discussion with Chris Lattner

llvm-svn: 194554

Add more owners to CODE_OWNERS.TXT (Kostya Serebryany: AddressSanitizer and ThreadSanitizer; Evgeniy Stepanov: MemorySanitizer)

llvm-svn: 185064

llvm-svn: 181434

llvm-svn: 179663

llvm-svn: 179224

If anyone objects please let me know.

llvm-svn: 179212

llvm-svn: 177298

llvm-svn: 176858

llvm-svn: 174056

llvm-svn: 172525