Commit Graph

20942 Commits

Author SHA1 Message Date
Tim Northover 1123323be2 GlobalISel: give MachineInstrBuilder a uniform interface. NFC.
Instead of an ad-hoc collection of "buildInstr" functions with varying numbers
of registers, this uses variadic templates to provide for as many regs as
needed!

Also make IRtranslator use new "buildBr" function instead of some weird generic
one that no-one else would really use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276762 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-26 16:45:26 +00:00
Matthias Braun bb936d2a6e LiveIntervalAnalysis: Fix handleMoveDown() problem
If we move a last-use register read to a later position we may skip
intermediate segments. This may require us to not only extend the
segment before the NewIdx, but also extend the segment live-in to
OldIdx.

This switches LiveIntervalTest to use AMDGPU so we can test subregister
liveness.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276724 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-26 03:57:45 +00:00
Tim Northover 6ba60326a1 GlobalISel: remove redundant ';'s. NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276723 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-26 03:29:18 +00:00
Evgeniy Stepanov 6f1298ed27 [safestack] Fix stack guard live range.
Stack guard slot is live throughout the function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276712 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-26 00:05:14 +00:00
Tim Northover 967b5082a2 GlobalISel: add generic casts to IRTranslator
This adds LLVM's 3 main cast instructions (inttoptr, ptrtoint, bitcast) to the
IRTranslator. The first two are direct translations (with 2 MachineInstr types
each). Since LLT discards information, a bitcast might become trivial and we
emit a COPY in those cases instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276690 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-25 21:01:29 +00:00
Matt Arsenault 065de94c4a MachineVerifier: Fix printing nonsense for physical registers
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276677 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-25 19:39:01 +00:00
Evgeniy Stepanov 4791de83c3 Fix invalid iterator use in safestack coloring.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276676 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-25 19:25:40 +00:00
Joel Jones 8a39975ebd MC] Provide an MCTargetOptions to implementors of MCAsmBackendCtorTy, NFC
Some targets, notably AArch64 for ILP32, have different relocation encodings
based upon the ABI. This is an enabling change, so a future patch can use the
ABIName from MCTargetOptions to chose which relocations to use. Tested using
check-llvm.

The corresponding change to clang is in: http://reviews.llvm.org/D16538

Patch by: Joel Jones

Differential Revision: https://reviews.llvm.org/D16213


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276654 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-25 17:18:28 +00:00
NAKAMURA Takumi 6b25086f00 Untabify.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276597 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-25 00:59:51 +00:00
Tim Northover 3921674c30 GlobalISel: allow multiple types on MachineInstrs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276481 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-22 22:13:36 +00:00
Tim Northover ea26cb1f48 GlobalISel: implement legalization pass, with just one transformation.
This adds the actual MachineLegalizeHelper to do the work and a trivial pass
wrapper that legalizes all instructions in a MachineFunction. Currently the
only transformation supported is splitting up a vector G_ADD into one acting on
smaller vectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276461 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-22 20:03:43 +00:00
Zachary Turner 4ab13f5ec5 [msf] Create LLVMDebugInfoMsf
This provides a better layering of responsibilities among different
aspects of PDB writing code.  Some of the MSF related code was
contained in CodeView, and some was in PDB prior to this.  Further,
we were often saying PDB when we meant MSF, and the two are
actually independent of each other since in theory you can have
other types of data besides PDB data in an MSF.  So, this patch
separates the MSF specific code into its own library, with no
dependencies on anything else, and DebugInfoCodeView and
DebugInfoPDB take dependencies on DebugInfoMsf.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276458 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-22 19:56:05 +00:00
Tim Northover 04e7d3ce19 GlobalISel: implement alloca instruction
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276433 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-22 16:59:52 +00:00
Simon Pilgrim 85f2423a35 [SelectionDAG] Optimization of BITREVERSE legalization for power-of-2 integer scalar/vector types
An extension of D19978, this patch replaces the default BITREVERSE evaluation of individual bit masks+shifts with block mask+shifts when we have integer elements of power-of-2 bits in size.

After calling BSWAP to reverse the order of the constituent bytes (which typically follows a similar approach), every neighbouring 4-bits, 2-bits and finally 1-bit pairs are masked off and swapped over with shifts.

In doing so we can significantly reduce the number of operations required.

Differential Revision: https://reviews.llvm.org/D21578

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276432 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-22 16:46:25 +00:00
Ahmed Bougacha e01551dfca [FastISel] Ignore @llvm.assume.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276410 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-22 12:54:53 +00:00
Quentin Colombet a2132baaff [MIRTesting] Abort when failing to parse a function.
When we failed to parse a function in the mir parser, we should abort
the whole compilation instead of continuing in a weird state. Indeed,
this was creating strange machine function passes failures that were
hard to understand, until we notice that the function actually did not
get parsed correctly!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276348 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-21 22:25:57 +00:00
Quentin Colombet 9abf24c5c4 [IRTranslator] Add G_SUB opcode.
This commit adds a generic SUB opcode to global-isel.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276308 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-21 17:26:50 +00:00
Quentin Colombet 368a8a2f01 [IRTranslator] Add comments to explain the ordering of the switch. NFC.
Group arithmetic operations, bitwise operations, and branch operations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276305 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-21 17:26:41 +00:00
Quentin Colombet 513679d9f5 [IRTranslator] Add G_AND opcode.
This commit adds a generic AND opcode to global-isel.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276297 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-21 15:50:42 +00:00
Marina Yatsina a264c851a4 ExecutionDepsFix - Fix bug in clearance calculation
The clearance calculation did not take into account registers defined as outputs or clobbers in inline assembly machine instructions because these register defs are implicit.

Differential Revision: http://reviews.llvm.org/D22580



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276266 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-21 12:37:07 +00:00
Matthias Braun fc02f97363 IPRA: Fix RegMask calculation for alias registers
This patch fixes a very subtle bug in regmask calculation. Thanks to zan
jyu Wong <zyfwong@gmail.com> for bringing this to notice.
For example if CL is only clobbered than CH should not be marked
clobbered but CX, RCX and ECX should be mark clobbered. Previously for
each modified register all of its aliases are marked clobbered by
markRegClobbred() in RegUsageInfoCollector.cpp but that is wrong because
when CL is clobbered then MRI::isPhysRegModified() will return true for
CL, CX, ECX, RCX which is correct behavior but then for CX, EXC, RCX we
mark CH also clobbered as CH is aliased to CX,ECX,RCX so
markRegClobbred() is not required because isPhysRegModified already take
cares of proper aliasing register. A very simple test case has been
added to verify this change.
Please find relevant bug report here :
http://llvm.org/PR28567

Patch by Vivek Pandya <vivekvpandya@gmail.com>

Differential Revision: https://reviews.llvm.org/D22400

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276235 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-21 03:50:39 +00:00
Tim Northover 6f08925c54 GlobalISel: implement Legalization querying framework.
This adds an (incomplete, inefficient) framework for deciding what to do with
some operation on a given type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276184 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-20 21:13:29 +00:00
Tim Northover 4951996d06 GlobalISel: implement low-level type with just size & vector lanes.
This should be all the low-level instruction selection needs to determine how
to implement an operation, with the remaining context taken from the opcode
(e.g. G_ADD vs G_FADD) or other flags not based on type (e.g. fast-math).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276158 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-20 19:09:30 +00:00
Matthias Braun e3d8cd87b2 Revert "RegScavenging: Add scavengeRegisterBackwards()"
Reverting this commit for now as it seems to be causing failures on
test-suite tests on the clang-ppc64le-linux-lnt bot.

This reverts commit r276044.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276068 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-20 00:21:32 +00:00
Kyle Butt 3d7281b8c9 Codegen: Tail Duplication: Only duplicate into layout pred if it is a CFG Pred.
Add a check that the layout predecessor of a block is an actual CFG
predecssor of the block as well. No current code fails this check, but
upcoming patches can trigger this, and it makes sense to separate it
out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276066 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-20 00:01:51 +00:00
Kyle Butt ebd8d9a1ff Codegen: Factor out canTailDuplicate
canTailDuplicate accepts two blocks and returns true if the first can be
duplicated into the second successfully. Use this function to
encapsulate the heuristic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276062 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 23:54:21 +00:00
Matthias Braun c5e14e0478 RegScavenging: Add scavengeRegisterBackwards()
This is a variant of scavengeRegister() that works for
enterBasicBlockEnd()/backward(). The benefit of the backward mode is
that it is not affected by incomplete kill flags.

This patch also changes
PrologEpilogInserter::doScavengeFrameVirtualRegs() to use the register
scavenger in backwards mode.

Differential Revision: http://reviews.llvm.org/D21885

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276044 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 22:37:09 +00:00
Matthias Braun e07c066cdd RegisterScavenger: Introduce backward() mode.
This adds two pieces:
- RegisterScavenger:::enterBasicBlockEnd() which behaves similar to
  enterBasicBlock() but starts tracking at the end of the basic block.
- A RegisterScavenger::backward() method. It is subtly different
  from the existing unprocess() method which only considers uses with
  the kill flag set: If a value is dead at the end of a basic block with
  a last use inside the basic block, unprocess() will fail to mark it as
  live. However we cannot change/fix this behaviour because unprocess()
  needs to perform the exact reverse operation of forward().

Differential Revision: http://reviews.llvm.org/D21873

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276043 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 22:37:02 +00:00
Ahmed Bougacha 98d2ab3a50 [GlobalISel] Mark newly-created gvregs as having a bank.
Also verify that we never try to set the size of a vreg associated
to a register class.

Report an error when we encounter that in MIR. Fix a testcase that
hit that error and had a size for no reason.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276012 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 19:48:36 +00:00
Ahmed Bougacha e627715b1b [GlobalISel] Simplify more RegClassOrRegBank is+get. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276011 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 19:47:06 +00:00
Elena Demikhovsky 87a79055a6 AVX-512: Fixed BT instruction selection.
The following condition expression ( a >> n) & 1 is converted to "bt a, n" instruction. It works on all intel targets.
But on AVX-512 it was broken because the expression is modified to (truncate (a >>n) to i1).

I added the new sequence (truncate (a >>n) to i1) to the BT pattern.

Differential Revision: https://reviews.llvm.org/D22354



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275950 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-19 07:14:21 +00:00
Tim Northover d7c16ef558 CodeGenPrep: use correct function to determine Global's alignment.
Elsewhere (particularly computeKnownBits) we assume that a global will be
aligned to the value returned by Value::getPointerAlignment. This is used to
boost the alignment on memcpy/memset, so any target-specific request can only
increase that value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275866 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-18 18:28:52 +00:00
Chih-Hung Hsieh f94271deae [X86] Accept SELECT op code for x86-64 fp128 type
DAGTypeLegalizer::CanSkipSoftenFloatOperand should allow
SELECT op code for x86_64 fp128 type for MME targets,
so SoftenFloatOperand does not abort on SELECT op code.

Differential Revision: http://reviews.llvm.org/D21758


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275818 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-18 17:20:09 +00:00
Simon Dardis 5ebefb8fd2 [inlineasm] Propagate operand constraints to the backend
When SelectionDAGISel transforms a node representing an inline asm
block, memory constraint information is not preserved. This can cause
constraints to be broken when a memory offset is of the form:

offset + frame index

when the frame is resolved.

By propagating the constraints all the way to the backend, targets can
enforce memory operands of inline assembly to conform to their constraints.

For MIPSR6, some instructions had their offsets reduced to 9 bits from
16 bits such as ll/sc. This becomes problematic when using inline assembly
to perform atomic operations, as an offset can generated that is too big to
encode in the instruction.

Reviewers: dsanders, vkalintris

Differential Review: https://reviews.llvm.org/D21615


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275786 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-18 13:17:31 +00:00
Dehao Chen 78ee4b6ec0 [PM] Convert IVUsers analysis to new pass manager.
Summary: Convert IVUsers analysis to new pass manager.

Reviewers: davidxl, silvas

Subscribers: junbuml, sanjoy, llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D22434

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275698 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-16 22:51:33 +00:00
Mehdi Amini bf11cc79f2 IPRA: avoid double query to the map (NFC)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275689 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-16 18:20:26 +00:00
Matthias Braun 4d5c34d999 MIParser: reject subregister indexes on physregs
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275658 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-16 01:36:18 +00:00
Michael Kuperstein 467260108e ExpandPostRAPseudos should transfer implicit uses, not only implicit defs
Previously, we would expand:
%BL<def> = COPY %DL<kill>, %EBX<imp-use,kill>, %EBX<imp-def>
Into:
%BL<def> = MOV8rr %DL<kill>, %EBX<imp-def>
Dropping the imp-use on the floor.

That confused CriticalAntiDepBreaker, which (correctly) assumes that if an
instruction defs but doesn't use a register, that register is dead immediately
before the instruction - while in this case, the high lanes of EBX can be very
much alive.

This fixes PR28560.

Differential Revision: https://reviews.llvm.org/D22425


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275634 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 22:31:14 +00:00
Saleem Abdulrasool 1083a5297a CodeGen: avoid emitting unnecessary CFI
Remove unnecessary clutter in assembly output.  When using SjLj EH, the CFI is
not actually used for anything.  Do not emit the CFI needlessly.  The minor test
adjustments are interesting.  The prologue test was just overzealous matcching.
The interesting case is the LSDA change.  It was originally added to ensure that
various compilations did not mangle the name (it explicitly checked the name!).
However, subsequent cleanups made it more reliant on the CFI to find the name.
Parse the generated code flow to generically find the label still.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275614 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 21:10:29 +00:00
Sjoerd Meijer aafccf0a58 [MBP] Clean up of the comments, and a first attempt to better describe a part
of the algorithm.

Differential Revision: https://reviews.llvm.org/D22364


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275595 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 18:41:56 +00:00
Justin Lebar b2d6ad7cfd [SelectionDAG] Get rid of bool parameters in SelectionDAG::getLoad, getStore, and friends.
Summary:
Instead, we take a single flags arg (a bitset).

Also add a default 0 alignment, and change the order of arguments so the
alignment comes before the flags.

This greatly simplifies many callsites, and fixes a bug in
AMDGPUISelLowering, wherein the order of the args to getLoad was
inverted.  It also greatly simplifies the process of adding another flag
to getLoad.

Reviewers: chandlerc, tstellarAMD

Subscribers: jholewinski, arsenm, jyknight, dsanders, nemanjai, llvm-commits

Differential Revision: http://reviews.llvm.org/D22249

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275592 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 18:27:10 +00:00
Justin Lebar 14fc45e102 [CodeGen] Take a MachineMemOperand::Flags in MachineFunction::getMachineMemOperand.
Summary:
Previously we took an unsigned.

Hooray for type-safety.

Reviewers: chandlerc

Subscribers: dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D22282

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275591 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 18:26:59 +00:00
Jacques Pienaar 48ed4ab2d6 Rename AnalyzeBranch* to analyzeBranch*.
Summary: NFC. Rename AnalyzeBranch/AnalyzeBranchPredicate to analyzeBranch/analyzeBranchPredicate to follow LLVM coding style and be consistent with TargetInstrInfo's analyzeCompare and analyzeSelect.

Reviewers: tstellarAMD, mcrosier

Subscribers: mcrosier, jholewinski, jfb, arsenm, dschuff, jyknight, dsanders, nemanjai

Differential Revision: https://reviews.llvm.org/D22409

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275564 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-15 14:41:04 +00:00
Reid Kleckner c61d5f4b2c [codeview] Shrink inlined call site line info tables
For a fully inlined call chain like a -> b -> c -> d, we were emitting
line info for 'd' 3 separate times: once for d's actual InlineSite line
table, and twice for 'b' and 'c'. This is particularly inefficient when
all these functions are in different headers, because now we need to
encode the file change. Windbg was coping with our suboptimal output, so
this should not be noticeable from the debugger.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275502 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 23:47:15 +00:00
Krzysztof Parzyszek 8bd1db4d74 Add debugging code to the packetizer
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275455 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 19:04:26 +00:00
Justin Lebar d4faf8fe43 [CodeGen] Refactor MachineMemOperand::Flags's target-specific flags.
Summary:
Make the target-specific flags in MachineMemOperand::Flags real, bona
fide enum values.  This simplifies users, prevents various constants
from going out of sync, and avoids the false sense of security provided
by declaring static members in classes and then forgetting to define
them inside of cpp files.

Reviewers: MatzeB

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22372

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275451 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 18:15:20 +00:00
Justin Lebar f66cee6be5 [CodeGen] Refactor MachineMemOperand's Flags enum.
Summary:
- Give it a shorter name (because we're going to refer to it often from
  SelectionDAG and friends).

- Split the flags and alignment into separate variables.

- Specialize FlagsEnumTraits for it, so we can do bitwise ops on it
  without losing type information.

- Make some enum values constants in MachineMemOperand instead.
  MOMaxBits should not be a valid Flag.

- Simplify some of the bitwise ops for dealing with Flags.

Reviewers: chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D22281

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275438 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 17:07:44 +00:00
Ahmed Bougacha 8b8511816c [GlobalISel] Fix #include ordering/spacing. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275423 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 14:52:55 +00:00
Dean Michael Berris f585634128 Remove extra ';' to appease -Wpedantic
Summary:

Reviewers: dok

Subscribers: llvm-commits

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275399 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 11:46:41 +00:00
Dean Michael Berris cee9af9136 XRay: Add entry and exit sleds
Summary:
In this patch we implement the following parts of XRay:

- Supporting a function attribute named 'function-instrument' which currently only supports 'xray-always'. We should be able to use this attribute for other instrumentation approaches.
- Supporting a function attribute named 'xray-instruction-threshold' used to determine whether a function is instrumented with a minimum number of instructions (IR instruction counts).
- X86-specific nop sleds as described in the white paper.
- A machine function pass that adds the different instrumentation marker instructions at a very late stage.
- A way of identifying which return opcode is considered "normal" for each architecture.

There are some caveats here:

1) We don't handle PATCHABLE_RET in platforms other than x86_64 yet -- this means if IR used PATCHABLE_RET directly instead of a normal ret, instruction lowering for that platform might do the wrong thing. We think this should be handled at instruction selection time to by default be unpacked for platforms where XRay is not availble yet.

2) The generated section for X86 is different from what is described from the white paper for the sole reason that LLVM allows us to do this neatly. We're taking the opportunity to deviate from the white paper from this perspective to allow us to get richer information from the runtime library.

Reviewers: sanjoy, eugenis, kcc, pcc, echristo, rnk

Subscribers: niravd, majnemer, atrick, rnk, emaste, bmakam, mcrosier, mehdi_amini, llvm-commits

Differential Revision: http://reviews.llvm.org/D19904

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275367 91177308-0d34-0410-b5e6-96231b3b80d8
2016-07-14 04:06:33 +00:00