llvm-6502/include/llvm/ADT
Alexei Starovoitov 4fe85c7548 BPF backend
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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227008 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-24 17:51:26 +00:00
..
APFloat.h [ADT] Add an (ADL-friendly) abs free function for APFloat that returns 2014-10-10 08:27:22 +00:00
APInt.h Reapply "LLVMContext: Store APInt/APFloat directly into the ConstantInt/FP DenseMaps." 2014-12-06 13:12:56 +00:00
APSInt.h APSInt: Simplify code to reduce the number of copies. No functionality change. 2014-10-12 15:36:31 +00:00
ArrayRef.h Revert r225053: Add an ArrayRef upcasting constructor from ArrayRef<U*> -> ArrayRef<T*> where T is a base of U. 2015-01-01 13:01:25 +00:00
BitVector.h Silence more static analyzer warnings. 2014-12-15 18:48:43 +00:00
DAGDeltaAlgorithm.h
DeltaAlgorithm.h
DenseMap.h Make the DenseMap bucket type configurable and use a smaller bucket for DenseSet. 2014-12-06 19:22:44 +00:00
DenseMapInfo.h
DenseSet.h Make the DenseMap bucket type configurable and use a smaller bucket for DenseSet. 2014-12-06 19:22:44 +00:00
DepthFirstIterator.h [cleanup] Re-sort all the #include lines in LLVM using 2015-01-14 11:23:27 +00:00
edit_distance.h
EquivalenceClasses.h
FoldingSet.h
GraphTraits.h
Hashing.h
ilist_node.h
ilist.h
ImmutableList.h
ImmutableMap.h
ImmutableSet.h
IndexedMap.h
IntEqClasses.h
IntervalMap.h
IntrusiveRefCntPtr.h
iterator_range.h [ADT] Remove the unused default constructor for iterator_range. 2015-01-11 01:16:26 +00:00
iterator.h [cleanup] Re-sort all the #include lines in LLVM using 2015-01-14 11:23:27 +00:00
MapVector.h Convert SmallMapVector from a class to a struct. 2015-01-05 08:55:19 +00:00
None.h
Optional.h Add an emplace(...) method to llvm::Optional<T>. 2014-10-01 02:12:35 +00:00
PackedVector.h
PointerIntPair.h
PointerUnion.h
PostOrderIterator.h Update template specialization to reflect API changes. 2014-11-20 19:33:30 +00:00
PriorityQueue.h
SCCIterator.h
ScopedHashTable.h Prune CRLF. 2014-10-27 12:37:26 +00:00
SetOperations.h
SetVector.h Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool> 2014-11-19 07:49:26 +00:00
SmallBitVector.h Silencing a *lot* of -Wsign-compare warnings; NFC. 2014-12-13 16:53:15 +00:00
SmallPtrSet.h Update SmallPtrSet::insert's doc comment to match the new return type 2014-12-19 21:45:11 +00:00
SmallSet.h Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool> 2014-11-19 07:49:26 +00:00
SmallString.h
SmallVector.h [ADT] Add move operations to SmallVector<T,N> from SmallVectorImpl<T>. 2015-01-23 06:25:17 +00:00
SparseBitVector.h Prune CRLF. 2014-10-27 12:37:26 +00:00
SparseMultiSet.h Prune CRLF. 2014-10-27 12:37:26 +00:00
SparseSet.h Prune CRLF. 2014-10-27 12:37:26 +00:00
Statistic.h
STLExtras.h Fix non-variadic function_ref cases to match r221753 2014-11-12 03:28:57 +00:00
StringExtras.h
StringMap.h ADT: Remove GetStringMapEntryFromValue() 2014-12-05 01:41:36 +00:00
StringRef.h Bitcode: Use unsigned char to record MDStrings 2014-12-11 23:34:30 +00:00
StringSet.h Make StringSet::insert return pair<iterator, bool> like other self-associative containers 2014-11-19 02:56:00 +00:00
StringSwitch.h
TinyPtrVector.h [tinyptrvector] Add in a MutableArrayRef implicit conversion operator to complement the ArrayRef implicit conversion operator. 2015-01-19 03:25:33 +00:00
Triple.h BPF backend 2015-01-24 17:51:26 +00:00
Twine.h Use a typed enum instead of 'unsigned char' for packed field. NFC. 2014-12-02 23:34:23 +00:00
UniqueVector.h
VariadicFunction.h