If a shufflevector's mask vector has an element with "undef" then the generic
instruction defining that element register is a G_IMPLICT_DEF instead of G_CONSTANT.
This fixes the selector to handle this case, and for now assumes that undef just means
zero. In future we'll optimize this case properly.
llvm-svn: 358312
Loads and store of values with type like <2 x p0> currently don't get imported
because SelectionDAG has no knowledge of pointer types. To leverage the existing
support for vector load/stores, we can bitcast the value to have s64 element
types instead. We do this as a custom legalization.
This patch also adds support for general loads of <2 x s64>, and relaxes some
type conditions on selecting G_BITCAST.
Differential Revision: https://reviews.llvm.org/D60534
llvm-svn: 358221
The selection for G_ICMP is unfortunately not currently importable from SDAG
due to the use of custom SDNodes. To support this, this selection method has an
opcode table which has been generated by a script, indexed by various
instruction properties. Ideally in future we will have a GISel native selection
patterns that we can write in tablegen to improve on this.
For selection of some types we also need support for G_ASHR and G_SHL which are
generated as a result of legalization. This patch also adds support for them,
generating the same code as SelectionDAG currently does.
Differential Revision: https://reviews.llvm.org/D60436
llvm-svn: 358035
This adds partial instruction selection support for llvm.aarch64.stlxr. It also
factors out selection for G_INTRINSIC_W_SIDE_EFFECTS into its own function. The
new function removes the restriction that the intrinsic ID on the
G_INTRINSIC_W_SIDE_EFFECTS be on operand 0.
Also add a test, and add a GISel line to arm64-ldxr-stxr.ll.
Differential Revision: https://reviews.llvm.org/D60100
llvm-svn: 357518
This adds support for v2s32 vector inserts, and updates the selection +
regbankselect tests for G_INSERT_VECTOR_ELT.
Differential Revision: https://reviews.llvm.org/D59910
llvm-svn: 357318
This adds pattern matching for the insert+shufflevector sequence so we can
generate dup instructions instead of the current TBL sequence.
Differential Revision: https://reviews.llvm.org/D59558
llvm-svn: 356526
After review comments, it was preferred to not teach MachineIRBuilder about
non-generic instructions beyond using buildInstr().
For AArch64 I've changed the buildCopy() calls to buildInstr() + a
separate addReg() call.
This also relaxes the MachineIRBuilder's COPY checking more because it may
not always have a SrcOp given to it.
llvm-svn: 356396
This relaxes some asserts about sizes, and adds an optional subreg parameter
to buildCopy().
Also update AArch64 instruction selector to use this in places where we
previously used MachineInstrBuilder manually.
Differential Revision: https://reviews.llvm.org/D59434
llvm-svn: 356304
This adds instruction selection support for G_UADDO on s32s and s64s.
Also
- Add an instruction selection test
- Update the arm64-xaluo.ll test to show that we generate the correct assembly
Differential Revision: https://reviews.llvm.org/D58734
llvm-svn: 356214
This re-uses the previous support for extract vector elt to extract the
subvectors.
Differential Revision: https://reviews.llvm.org/D59390
llvm-svn: 356213
This adds support for inserting elements into packed vectors. It also adds
two tests: one for selection, and one for regbank select.
Unpacked vectors will come in a follow-up.
Differential Revision: https://reviews.llvm.org/D59325
llvm-svn: 356182
NFC. Some more preliminary factoring for G_INSERT_VECTOR_ELT.
Also better code-reuse, etc., etc.
Differential Revision: https://reviews.llvm.org/D59323
llvm-svn: 356107
Factor out the vector insert code in `selectBuildVector`. Replace part of it
with `emitScalarToVector`, since it was pretty much equivalent.
This will make implementing G_INSERT_VECTOR_ELT easier.
Differential Revision: https://reviews.llvm.org/D59322
llvm-svn: 356106
Some more refactoring for G_INSERT_VECTOR_ELT.
Factor out the code used to find a lane index from `selectExtractElt`. Put it
into a more general-purpose `getConstantValueForReg` function.
This will be shared with the code for G_INSERT_VECTOR_ELT.
Differential Revision: https://reviews.llvm.org/D59324
llvm-svn: 356101
After r355865, we should be able to safely select G_EXTRACT_VECTOR_ELT without
running into any problematic intrinsics.
Also add a fix for lane copies, which don't support index 0.
llvm-svn: 355871
This adds instruction selection support for G_EXTRACT_VECTOR_ELT for cases
where the index is defined by a G_CONSTANT.
It also factos out the lane copy opcode selection part into its own function,
`getLaneCopyOpcode`. This is used by both `selectUnmergeValues` and
`selectExtractElt`.
Differential Revision: https://reviews.llvm.org/D58469
llvm-svn: 355344
The code to materialize a mask from a constant pool load tried to use a 128 bit
LDR to load a 64 bit constant pool entry, which was 8 byte aligned. This resulted
in a link failure in the NEON tests in the test suite since the LDR address was
unaligned. This change fixes that to instead emit a 64 bit LDR if the entry is
64 bit, before converting back to a 128 bit register for the TBL.
llvm-svn: 355326
1) GCC complains that KnownValid is set but not used.
2) In ARMInstructionSelector::selectGlobal() the code is mixing "enumeral
and non-enumeral type in conditional expression". Solve this by casting
to unsigned which is the final type anyway.
Differential Revision: https://reviews.llvm.org/D58834
llvm-svn: 355304
This extends the existing support for shufflevector to handle cases like
<2 x float>, which we can implement by concating the vectors and using a TBL1.
Differential Revision: https://reviews.llvm.org/D58684
llvm-svn: 355104
This is a preparatory change as I want to use emitScalarToVector() elsewhere,
and in general we want to transition to MIRBuilder instead of using BuildMI
directly.
Differential Revision: https://reviews.llvm.org/D58528
llvm-svn: 354807
This change makes some basic type combinations for G_SHUFFLE_VECTOR legal, and
implements them with a very pessimistic TBL2 instruction in the selector.
For TBL2, support is also needed to generate constant pool entries and load from
them in order to materialize the mask register.
Currently supports <2 x s64> and <4 x s32> result types.
Differential Revision: https://reviews.llvm.org/D58466
llvm-svn: 354521
https://reviews.llvm.org/D57608
It's a common pattern in GISel to have a MachineInstrBuilder from which we get various regs
(commonly MIB->getOperand(0).getReg()). This adds a helper method and the above can be
replaced with MIB.getReg(0).
llvm-svn: 353223
This patch adds support for vector @llvm.ceil intrinsics when full 16 bit
floating point support isn't available.
To do this, this patch...
- Implements basic isel for G_UNMERGE_VALUES
- Teaches the legalizer about 16 bit floats
- Teaches AArch64RegisterBankInfo to respect floating point registers on
G_BUILD_VECTOR and G_UNMERGE_VALUES
- Teaches selectCopy about 16-bit floating point vectors
It also adds
- A legalizer test for the 16-bit vector ceil which verifies that we create a
G_UNMERGE_VALUES and G_BUILD_VECTOR when full fp16 isn't supported
- An instruction selection test which makes sure we lower to G_FCEIL when
full fp16 is supported
- A test for selecting G_UNMERGE_VALUES
And also updates arm64-vfloatintrinsics.ll to show that the new ceiling types
work as expected.
https://reviews.llvm.org/D56682
llvm-svn: 352113
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
This code pattern is an unfortunate side effect of the way some types get split
at call lowering. Ideally we'd either not generate it at all or combine it away
in the legalizer artifact combiner.
Until then, add selection support anyway which is a significant proportion of
our current fallbacks on CTMark.
rdar://46491420
llvm-svn: 349712
The pass implements tracking of control flow miss-speculation into a "taint"
register. That taint register can then be used to mask off registers with
sensitive data when executing under miss-speculation, a.k.a. "transient
execution".
This pass is aimed at mitigating against SpectreV1-style vulnarabilities.
At the moment, it implements the tracking of miss-speculation of control
flow into a taint register, but doesn't implement a mechanism yet to then
use that taint register to mask off vulnerable data in registers (something
for a follow-on improvement). Possible strategies to mask out vulnerable
data that can be implemented on top of this are:
- speculative load hardening to automatically mask of data loaded
in registers.
- using intrinsics to mask of data in registers as indicated by the
programmer (see https://lwn.net/Articles/759423/).
For AArch64, the following implementation choices are made.
Some of these are different than the implementation choices made in
the similar pass implemented in X86SpeculativeLoadHardening.cpp, as
the instruction set characteristics result in different trade-offs.
- The speculation hardening is done after register allocation. With a
relative abundance of registers, one register is reserved (X16) to be
the taint register. X16 is expected to not clash with other register
reservation mechanisms with very high probability because:
. The AArch64 ABI doesn't guarantee X16 to be retained across any call.
. The only way to request X16 to be used as a programmer is through
inline assembly. In the rare case a function explicitly demands to
use X16/W16, this pass falls back to hardening against speculation
by inserting a DSB SYS/ISB barrier pair which will prevent control
flow speculation.
- It is easy to insert mask operations at this late stage as we have
mask operations available that don't set flags.
- The taint variable contains all-ones when no miss-speculation is detected,
and contains all-zeros when miss-speculation is detected. Therefore, when
masking, an AND instruction (which only changes the register to be masked,
no other side effects) can easily be inserted anywhere that's needed.
- The tracking of miss-speculation is done by using a data-flow conditional
select instruction (CSEL) to evaluate the flags that were also used to
make conditional branch direction decisions. Speculation of the CSEL
instruction can be limited with a CSDB instruction - so the combination of
CSEL + a later CSDB gives the guarantee that the flags as used in the CSEL
aren't speculated. When conditional branch direction gets miss-speculated,
the semantics of the inserted CSEL instruction is such that the taint
register will contain all zero bits.
One key requirement for this to work is that the conditional branch is
followed by an execution of the CSEL instruction, where the CSEL
instruction needs to use the same flags status as the conditional branch.
This means that the conditional branches must not be implemented as one
of the AArch64 conditional branches that do not use the flags as input
(CB(N)Z and TB(N)Z). This is implemented by ensuring in the instruction
selectors to not produce these instructions when speculation hardening
is enabled. This pass will assert if it does encounter such an instruction.
- On function call boundaries, the miss-speculation state is transferred from
the taint register X16 to be encoded in the SP register as value 0.
Future extensions/improvements could be:
- Implement this functionality using full speculation barriers, akin to the
x86-slh-lfence option. This may be more useful for the intrinsics-based
approach than for the SLH approach to masking.
Note that this pass already inserts the full speculation barriers if the
function for some niche reason makes use of X16/W16.
- no indirect branch misprediction gets protected/instrumented; but this
could be done for some indirect branches, such as switch jump tables.
Differential Revision: https://reviews.llvm.org/D54896
llvm-svn: 349456
https://reviews.llvm.org/D55294
Previously MachineIRBuilder::buildInstr used to accept variadic
arguments for sources (which were either unsigned or
MachineInstrBuilder). While this worked well in common cases, it doesn't
allow us to build instructions that have multiple destinations.
Additionally passing in other optional parameters in the end (such as
flags) is not possible trivially. Also a trivial call such as
B.buildInstr(Opc, Reg1, Reg2, Reg3)
can be interpreted differently based on the opcode (2defs + 1 src for
unmerge vs 1 def + 2srcs).
This patch refactors the buildInstr to
buildInstr(Opc, ArrayRef<DstOps>, ArrayRef<SrcOps>)
where DstOps and SrcOps are typed unions that know how to add itself to
MachineInstrBuilder.
After this patch, most invocations would look like
B.buildInstr(Opc, {s32, DstReg}, {SrcRegs..., SrcMIBs..});
Now all the other calls (such as buildAdd, buildSub etc) forward to
buildInstr. It also makes it possible to build instructions with
multiple defs.
Additionally in a subsequent patch, we should make it possible to add
flags directly while building instructions.
Additionally, the main buildInstr method is now virtual and other
builders now only have to override buildInstr (for say constant
folding/cseing) is straightforward.
Also attached here (https://reviews.llvm.org/F7675680) is a clang-tidy
patch that should upgrade the API calls if necessary.
llvm-svn: 348815
This patch restricts the capability of G_MERGE_VALUES, and uses the new
G_BUILD_VECTOR and G_CONCAT_VECTORS opcodes instead in the appropriate places.
This patch also includes AArch64 support for selecting G_BUILD_VECTOR of <4 x s32>
and <2 x s64> vectors.
Differential Revisions: https://reviews.llvm.org/D53629
llvm-svn: 348788
We previously disabled this in r323371 because of a bug where we selected an
extending load, but didn't delete the old G_LOAD, resulting in two loads being
generated for volatile loads.
Since we now have dedicated G_SEXTLOAD/G_ZEXTLOAD operations, and that the
tablegen patterns should no longer be able to select (ext(load x)) patterns, it
should be safe to re-enable it.
The old test case should still work as expected.
llvm-svn: 348320
This adds the plumbing for the Tiny code model for the AArch64 backend. This,
instead of loading addresses through the normal ADRP;ADD pair used in the Small
model, uses a single ADR. The 21 bit range of an ADR means that the code and
its statically defined symbols need to be within 1MB of each other.
This makes it mostly interesting for embedded applications where we want to fit
as much as we can in as small a space as possible.
Differential Revision: https://reviews.llvm.org/D49673
llvm-svn: 340397
Also refactors some existing code to materialize addresses for the large code
model so it can be shared between G_GLOBAL_VALUE and G_BLOCK_ADDR.
This implements PR36390.
Differential Revision: https://reviews.llvm.org/D49903
llvm-svn: 338337
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.
In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.
Differential Revision: https://reviews.llvm.org/D43624
llvm-svn: 332240
Summary:
Previously, a extending load was represented at (G_*EXT (G_LOAD x)).
This had a few drawbacks:
* G_LOAD had to be legal for all sizes you could extend from, even if
registers didn't naturally hold those sizes.
* All sizes you could extend from had to be allocatable just in case the
extend went missing (e.g. by optimization).
* At minimum, G_*EXT and G_TRUNC had to be legal for these sizes. As we
improve optimization of extends and truncates, this legality requirement
would spread without considerable care w.r.t when certain combines were
permitted.
* The SelectionDAG importer required some ugly and fragile pattern
rewriting to translate patterns into this style.
This patch changes the representation to:
* (G_[SZ]EXTLOAD x)
* (G_LOAD x) any-extends when MMO.getSize() * 8 < ResultTy.getSizeInBits()
which resolves these issues by allowing targets to work entirely in their
native register sizes, and by having a more direct translation from
SelectionDAG patterns.
Each extending load can be lowered by the legalizer into separate extends
and loads, however a target that supports s1 will need the any-extending
load to extend to at least s8 since LLVM does not represent memory accesses
smaller than 8 bit. The legalizer can widenScalar G_LOAD into an
any-extending load but sign/zero-extending loads need help from something
else like a combiner pass. A follow-up patch that adds combiner helpers for
for this will follow.
The new representation requires that the MMO correctly reflect the memory
access so this has been corrected in a couple tests. I've also moved the
extending loads to their own tests since they are (mostly) separate opcodes
now. Additionally, the re-write appears to have invalidated two tests from
select-with-no-legality-check.mir since the matcher table no longer contains
loads that result in s1's and they aren't legal in AArch64 anymore.
Depends on D45540
Reviewers: ab, aditya_nandakumar, bogner, rtereshin, volkan, rovka, javed.absar
Reviewed By: rtereshin
Subscribers: javed.absar, llvm-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D45541
llvm-svn: 331601
This is a follow on commit to r[x] where we fix the other direction of copy.
For this case, after converting the source from gpr32 -> fpr32, we use a
subregister copy, which is essentially what EXTRACT_SUBREG does in SDAG land.
https://reviews.llvm.org/D43444
llvm-svn: 325550
Amara Emerson