Commit Graph

47 Commits

Author SHA1 Message Date
Daniel Sanders
4ddb0ced90 Replace string GNU Triples with llvm::Triple in TargetMachine. NFC.
Summary:
For the moment, TargetMachine::getTargetTriple() still returns a StringRef.

This continues the patch series to eliminate StringRef forms of GNU triples
from the internals of LLVM that began in r239036.

Reviewers: rengolin

Reviewed By: rengolin

Subscribers: ted, llvm-commits, rengolin, jholewinski

Differential Revision: http://reviews.llvm.org/D10362

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239554 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-11 19:41:26 +00:00
Ahmed Bougacha
fd83cb21ce [CodeGen] ArrayRef'ize cond/pred in various TII APIs. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239553 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-11 19:30:37 +00:00
Daniel Sanders
4d13f315d1 Replace string GNU Triples with llvm::Triple in MCSubtargetInfo and create*MCSubtargetInfo(). NFC.
Summary:
This continues the patch series to eliminate StringRef forms of GNU triples
from the internals of LLVM that began in r239036.

Reviewers: rafael

Reviewed By: rafael

Subscribers: rafael, ted, jfb, llvm-commits, rengolin, jholewinski

Differential Revision: http://reviews.llvm.org/D10311


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239467 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-10 12:11:26 +00:00
Daniel Sanders
03c060b6d4 Replace string GNU Triples with llvm::Triple in MCAsmBackend subclasses and create*AsmBackend(). NFC.
Summary:
This continues the patch series to eliminate StringRef forms of GNU triples
from the internals of LLVM that began in r239036.

Reviewers: echristo, rafael

Reviewed By: rafael

Subscribers: rafael, llvm-commits, rengolin

Differential Revision: http://reviews.llvm.org/D10243

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239464 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-10 10:35:34 +00:00
Alexei Starovoitov
b6ebf678ac [bpf] rename triple names bpf_be -> bpfeb
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239162 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-05 16:11:14 +00:00
Jim Grosbach
bc81286cac MC: Clean up naming in MCObjectWriter. NFC.
s/WriteObject/writeObject/
s/RecordRelocation/recordRelocation/
s/IsSymbolRefDifferenceFullyResolved/isSymbolRefDifferenceFullyResolved/
s/Write8/write8/
s/WriteLE16/writeLE16/
s/WriteLE32/writeLE32/
s/WriteLE64/writeLE64/
s/WriteBE16/writeBE16/
s/WriteBE32/writeBE32/
s/WriteBE64/writeBE64/
s/Write16/write16/
s/Write32/write32/
s/Write64/write64/
s/WriteZeroes/writeZeroes/
s/WriteBytes/writeBytes/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239108 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-04 22:24:41 +00:00
Alexei Starovoitov
ac73683b10 [bpf] add big- and host- endian support
Summary:
-march=bpf    -> host endian
-march=bpf_le -> little endian
-match=bpf_be -> big endian

Test Plan:
v1 was tested by IBM s390 guys and appears to be working there.
It bit rots too fast here.

Reviewers: chandlerc, tstellarAMD

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10177

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239071 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-04 19:15:05 +00:00
Benjamin Kramer
7ec7c7d865 Replace custom fixed endian to raw_ostream emission with EndianStream.
Less code, clearer and more efficient. No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239040 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-04 15:03:02 +00:00
Daniel Sanders
6ff6fc6055 Replace string GNU Triples with llvm::Triple in MCAsmInfo subclasses and create*AsmInfo(). NFC.
Summary:
This is the first of several patches to eliminate StringRef forms of GNU
triples from the internals of LLVM. After this is complete, GNU triples
will be replaced by a more authoratitive representation in the form of
an LLVM TargetTuple.

Reviewers: rengolin

Reviewed By: rengolin

Subscribers: ted, llvm-commits, rengolin, jholewinski

Differential Revision: http://reviews.llvm.org/D10236


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239036 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-04 13:12:25 +00:00
Alexei Starovoitov
0b48e9a83c [bpf] fix build
fix breakage due to r238634

Patch by Vijay Subramanian.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238792 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-01 22:24:36 +00:00
Alexei Starovoitov
1fd101c86d [bpf] emit jmp fixups in little endian
The 'off' field of 'struct bpf_insn' is in cpu-endianness,
since the rest is emitted as little endian, make sure
that 'off' field is little endian as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238038 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-22 18:47:33 +00:00
Alexei Starovoitov
a6f501cb97 [bpf] fix build
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237751 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-20 00:20:26 +00:00
Jim Grosbach
21a996a0e3 MC: MCCodeGenInfo naming update. NFC.
s/InitMCCodeGenInfo/initMCCodeGenInfo/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237471 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-15 19:13:31 +00:00
Jim Grosbach
251a66ec37 MC: Update MCCodeEmitter naming. NFC.
s/EncodeInstruction/encodeInstruction/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237469 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-15 19:13:16 +00:00
Jim Grosbach
8b22e9c00a MC: Update MCFixup naming. NFC.
s/MCFixup::Create/MCFixup::create/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237468 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-15 19:13:05 +00:00
Jim Grosbach
db703aaedd MC: Modernize MCOperand API naming. NFC.
MCOperand::Create*() methods renamed to MCOperand::create*().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237275 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-13 18:37:00 +00:00
Matthias Braun
bbff669c18 Change getTargetNodeName() to produce compiler warnings for missing cases, fix them
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236775 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-07 21:33:59 +00:00
Quentin Colombet
2f7322b348 [ShrinkWrap] Add (a simplified version) of shrink-wrapping.
This patch introduces a new pass that computes the safe point to insert the
prologue and epilogue of the function.
The interest is to find safe points that are cheaper than the entry and exits
blocks.

As an example and to avoid regressions to be introduce, this patch also
implements the required bits to enable the shrink-wrapping pass for AArch64.


** Context **

Currently we insert the prologue and epilogue of the method/function in the
entry and exits blocks. Although this is correct, we can do a better job when
those are not immediately required and insert them at less frequently executed
places.
The job of the shrink-wrapping pass is to identify such places.


** Motivating example **

Let us consider the following function that perform a call only in one branch of
a if:
define i32 @f(i32 %a, i32 %b)  {
 %tmp = alloca i32, align 4
 %tmp2 = icmp slt i32 %a, %b
 br i1 %tmp2, label %true, label %false

true:
 store i32 %a, i32* %tmp, align 4
 %tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
 br label %false

false:
 %tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
 ret i32 %tmp.0
}

On AArch64 this code generates (removing the cfi directives to ease
readabilities):
_f:                                     ; @f
; BB#0:
  stp x29, x30, [sp, #-16]!
  mov  x29, sp
  sub sp, sp, #16             ; =16
  cmp  w0, w1
  b.ge  LBB0_2
; BB#1:                                 ; %true
  stur  w0, [x29, #-4]
  sub x1, x29, #4             ; =4
  mov  w0, wzr
  bl  _doSomething
LBB0_2:                                 ; %false
  mov  sp, x29
  ldp x29, x30, [sp], #16
  ret

With shrink-wrapping we could generate:
_f:                                     ; @f
; BB#0:
  cmp  w0, w1
  b.ge  LBB0_2
; BB#1:                                 ; %true
  stp x29, x30, [sp, #-16]!
  mov  x29, sp
  sub sp, sp, #16             ; =16
  stur  w0, [x29, #-4]
  sub x1, x29, #4             ; =4
  mov  w0, wzr
  bl  _doSomething
  add sp, x29, #16            ; =16
  ldp x29, x30, [sp], #16
LBB0_2:                                 ; %false
  ret

Therefore, we would pay the overhead of setting up/destroying the frame only if
we actually do the call.


** Proposed Solution **

This patch introduces a new machine pass that perform the shrink-wrapping
analysis (See the comments at the beginning of ShrinkWrap.cpp for more details).
It then stores the safe save and restore point into the MachineFrameInfo
attached to the MachineFunction.
This information is then used by the PrologEpilogInserter (PEI) to place the
related code at the right place. This pass runs right before the PEI.

Unlike the original paper of Chow from PLDI’88, this implementation of
shrink-wrapping does not use expensive data-flow analysis and does not need hack
to properly avoid frequently executed point. Instead, it relies on dominance and
loop properties.

The pass is off by default and each target can opt-in by setting the
EnableShrinkWrap boolean to true in their derived class of TargetPassConfig.
This setting can also be overwritten on the command line by using
-enable-shrink-wrap.

Before you try out the pass for your target, make sure you properly fix your
emitProlog/emitEpilog/adjustForXXX method to cope with basic blocks that are not
necessarily the entry block.


** Design Decisions **

1. ShrinkWrap is its own pass right now. It could frankly be merged into PEI but
for debugging and clarity I thought it was best to have its own file.
2. Right now, we only support one save point and one restore point. At some
point we can expand this to several save point and restore point, the impacted
component would then be:
- The pass itself: New algorithm needed.
- MachineFrameInfo: Hold a list or set of Save/Restore point instead of one
  pointer.
- PEI: Should loop over the save point and restore point.
Anyhow, at least for this first iteration, I do not believe this is interesting
to support the complex cases. We should revisit that when we motivating
examples.

Differential Revision: http://reviews.llvm.org/D9210

<rdar://problem/3201744>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236507 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-05 17:38:16 +00:00
Alexei Starovoitov
04877fa7ff [bpf] fix build
Patch by Brenden Blanco.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236030 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-28 20:38:56 +00:00
Alexei Starovoitov
ad82d26669 [bpf] fix build and remove a compiler warning in Release mode
Patch by Brenden Blanco.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235814 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-26 01:58:08 +00:00
Alexei Starovoitov
49b5acf658 [bpf] fix build
fix build due to refactoring in DIL/MDL and raw_pwrite_stream

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234971 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-15 02:48:57 +00:00
Benjamin Kramer
0973b7ddb8 Reduce dyn_cast<> to isa<> or cast<> where possible.
No functional change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234586 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-10 11:24:51 +00:00
Alexei Starovoitov
34354ecc30 [bpf] support BPF backend as shared library
dependencies were not set correctly for shared library build.
static was ok

Patch by Brenden Blanco.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234386 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-08 03:46:51 +00:00
Alexei Starovoitov
68e6b651a1 [bpf] fix build
fix the build and remove unused variable warnings in Release mode.

Patch by Brenden Blanco.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234349 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-07 20:25:34 +00:00
Alexei Starovoitov
8ffc5ca532 [bpf] mark mov instructions as ReMaterializable
loading immediate into register is cheap, so take advantage of remat.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233666 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-31 02:49:58 +00:00
Eric Christopher
e2424b02b2 Replace the MCSubtargetInfo parameter with a Triple when creating
an MCInstPrinter. Update all callers and use where we wanted a Triple
previously.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233648 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-31 00:10:04 +00:00
Alexei Starovoitov
5ca9ec70fd [bpf] add support for bswap instructions
BPF has cpu_to_be and cpu_to_le instructions.
For now assume little endian and generate cpu_to_be for ISD::BSWAP.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233620 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-30 22:40:40 +00:00
Alexei Starovoitov
adb58c18f5 [bpf] fix build
fix build broken due to r233599.
Would still need to switch to MDLocation long term.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233619 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-30 22:40:35 +00:00
Eric Christopher
1c60a4e36b Remove unused Target argument from MCInstPrinter ctor functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233607 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-30 21:52:21 +00:00
Akira Hatanaka
f09378397e [MCInstPrinter] Enable MCInstPrinter to change its behavior based on the
per-function subtarget.

Currently, code-gen passes the default or generic subtarget to the constructors
of MCInstPrinter subclasses (see LLVMTargetMachine::addPassesToEmitFile), which
enables some targets (AArch64, ARM, and X86) to change their instprinter's
behavior based on the subtarget feature bits. Since the backend can now use
different subtargets for each function, instprinter has to be changed to use the
per-function subtarget rather than the default subtarget.

This patch takes the first step towards enabling instprinter to change its
behavior based on the per-function subtarget. It adds a bit "PassSubtarget" to
AsmWriter which tells table-gen to pass a reference to MCSubtargetInfo to the
various print methods table-gen auto-generates. 

I will follow up with changes to instprinters of AArch64, ARM, and X86.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233411 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-27 20:36:02 +00:00
Alexei Starovoitov
4193093152 [bpf] add support for bpf pseudo instruction
Expose bpf pseudo load instruction via intrinsic. It is used by front-ends that
can encode file descriptors directly into IR instead of relying on relocations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233396 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-27 18:51:42 +00:00
Benjamin Kramer
1bfcd1f675 Re-sort includes with sort-includes.py and insert raw_ostream.h where it's used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232998 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-23 19:32:43 +00:00
Eric Christopher
4638c99333 Remove the target independent TargetMachine::getSubtarget and
TargetMachine::getSubtargetImpl routines.

This keeps the target independent code free of bare subtarget
calls while the remainder of the backends are migrated, or not
if they don't wish to support per-function subtargets as would
be needed for function multiversioning or LTO of disparate
cpu subarchitecture types, e.g.

clang -msse4.2 -c foo.c -emit-llvm -o foo.bc
clang -c bar.c -emit-llvm -o bar.bc
llvm-link foo.bc bar.bc -o baz.bc
llc baz.bc

and get appropriate code for what the command lines requested.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232885 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-21 04:22:23 +00:00
Alexei Starovoitov
2611a42321 [bpf] fix build
fix BPF backend build broken by r232699

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232795 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-20 02:35:29 +00:00
Alexei Starovoitov
e3626baa58 [bpf] fix build
fix BPF backend build broken by r232429

Patch by Brenden Blanco

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232581 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-18 01:39:40 +00:00
David Blaikie
7610ba7d24 Fix uses of reserved identifiers starting with an underscore followed by an uppercase letter
This covers essentially all of llvm's headers and libs. One or two weird
cases I wasn't sure were worth/appropriate to fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232394 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 18:06:57 +00:00
Alexei Starovoitov
d5dd5dcb9c bpf: turn on HasJIT flag in BPF backend
basic tests that use BPF backend to produce code in memory are passing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232222 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-13 22:03:25 +00:00
Alexei Starovoitov
8b5546f6d5 bpf: fix build
fix missed bits which were left over after r231987

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232208 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-13 20:49:38 +00:00
Mehdi Amini
ceb9150268 Move the DataLayout to the generic TargetMachine, making it mandatory.
Summary:
I don't know why every singled backend had to redeclare its own DataLayout.
There was a virtual getDataLayout() on the common base TargetMachine, the
default implementation returned nullptr. It was not clear from this that
we could assume at call site that a DataLayout will be available with
each Target.

Now getDataLayout() is no longer virtual and return a pointer to the
DataLayout member of the common base TargetMachine. I plan to turn it into
a reference in a future patch.

The only backend that didn't have a DataLayout previsouly was the CPPBackend.
It now initializes the default DataLayout. This commit is NFC for all the
other backends.

Test Plan: clang+llvm ninja check-all

Reviewers: echristo

Subscribers: jfb, jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D8243

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231987 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 00:07:24 +00:00
Eric Christopher
5233c26b6b Have getCalleeSavedRegs take a non-null MachineFunction all the
time. The target independent code was passing in one all the
time and targets weren't checking validity before using. Update
a few calls to pass in a MachineFunction where necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231970 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-11 21:41:28 +00:00
Alexei Starovoitov
ae27891f8e bpf: fix build
complete the plumbing of passing TargetRegisterInfo through
computeRegisterProperties started by r230583

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230858 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-28 18:03:04 +00:00
Eric Christopher
a01bc6a59f Remove an argument-less call to getSubtargetImpl from TargetLoweringBase.
This required plumbing a TargetRegisterInfo through computeRegisterProperties
and into findRepresentativeClass which uses it for register class
iteration. This required passing a subtarget into a few target specific
initializations of TargetLowering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230583 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-26 00:00:24 +00:00
Aaron Ballman
66981fe208 Removing LLVM_DELETED_FUNCTION, as MSVC 2012 was the last reason for requiring the macro. NFC; LLVM edition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229340 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-15 22:54:22 +00:00
Chandler Carruth
417c5c172c [PM] Remove the old 'PassManager.h' header file at the top level of
LLVM's include tree and the use of using declarations to hide the
'legacy' namespace for the old pass manager.

This undoes the primary modules-hostile change I made to keep
out-of-tree targets building. I sent an email inquiring about whether
this would be reasonable to do at this phase and people seemed fine with
it, so making it a reality. This should allow us to start bootstrapping
with modules to a certain extent along with making it easier to mix and
match headers in general.

The updates to any code for users of LLVM are very mechanical. Switch
from including "llvm/PassManager.h" to "llvm/IR/LegacyPassManager.h".
Qualify the types which now produce compile errors with "legacy::". The
most common ones are "PassManager", "PassManagerBase", and
"FunctionPassManager".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229094 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-13 10:01:29 +00:00
Alexei Starovoitov
8ea8f377aa bpf: Use the getSubtarget call off of the MachineFunction rather than the TargetMachine
Summary:
Hi Eric,

this patch cleans up the layering violation that you're fixing across backends.
Anything else I need to fix on bpf backend side?

Thanks

Reviewers: echristo

Reviewed By: echristo

Differential Revision: http://reviews.llvm.org/D7355

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227865 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-02 21:24:27 +00:00
Alexei Starovoitov
bcd2c28872 bpf: fix build due to 'Move DataLayout back to the TargetMachine'
commit r227113 moved DataLayout

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227133 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-26 20:43:15 +00:00
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