| Commit message (Collapse) | Author | Age | Files | Lines |
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This patch aims to reduce spilling and register moves by using the 3-address
versions of instructions per default instead of the 2-address equivalent
ones. It seems that both spilling and register moves are improved noticeably
generally.
Regalloc hints are passed to increase conversions to 2-address instructions
which are done in SystemZShortenInst.cpp (after regalloc).
Since the SystemZ reg/mem instructions are 2-address (dst and lhs regs are
the same), foldMemoryOperandImpl() can no longer trivially fold a spilled
source register since the reg/reg instruction is now 3-address. In order to
remedy this, new 3-address pseudo memory instructions are used to perform the
folding only when the dst and lhs virtual registers are known to be allocated
to the same physreg. In order to not let MachineCopyPropagation run and
change registers on these transformed instructions (making it 3-address), a
new target pass called SystemZPostRewrite.cpp is run just after
VirtRegRewriter, that immediately lowers the pseudo to a target instruction.
If it would have been possibe to insert a COPY instruction and change a
register operand (convert to 2-address) in foldMemoryOperandImpl() while
trusting that the caller (e.g. InlineSpiller) would update/repair the
involved LiveIntervals, the solution involving pseudo instructions would not
have been needed. This is perhaps a potential improvement (see Phabricator
post).
Common code changes:
* A new hook TargetPassConfig::addPostRewrite() is utilized to be able to run a
target pass immediately before MachineCopyPropagation.
* VirtRegMap is passed as an argument to foldMemoryOperand().
Review: Ulrich Weigand, Quentin Colombet
https://reviews.llvm.org/D60888
llvm-svn: 362868
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Summary:
It looks like since INLINEASM_BR was created off of INLINEASM, a few
checks for INLINEASM needed to be updated to check for either case.
pr/41999
Reviewers: t.p.northover, peter.smith
Reviewed By: peter.smith
Subscribers: craig.topper, javed.absar, kristof.beyls, hiraditya, llvm-commits, peter.smith, srhines
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62402
llvm-svn: 361661
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This fix is for the problem from https://bugs.llvm.org/show_bug.cgi?id=38714.
Specifically, Simple Register Coalescing creates following conversion :
undef %0.sub_32:gpr64 = ORRWrs $wzr, %3:gpr32common, 0, debug-location !24;
It copies 32-bit value from gpr32 into gpr64. But Live DEBUG_VALUE analysis
is not able to create debug location record for that instruction. So the problem
is in that debug info for argc variable is incorrect. The fix is
to write custom isCopyInstrImpl() which would recognize the ORRWrs instr.
llvm-svn: 361417
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Summary:
Otherwise, we emit directives for CFI without any actual CFI opcodes to
go with them, which causes tools to malfunction. The technique is
similar to what the x86 backend already does.
Fixes https://bugs.llvm.org/show_bug.cgi?id=40876
Patch by: froydnj (Nathan Froyd)
Reviewers: mstorsjo, eli.friedman, rnk, mgrang, ssijaric
Reviewed By: rnk
Subscribers: javed.absar, kristof.beyls, llvm-commits, dmajor
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61960
llvm-svn: 360816
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This patch provides intrinsics support for Memory Tagging Extension (MTE),
which was introduced with the Armv8.5-a architecture.
The intrinsics are described in detail in the latest
ACLE Q1 2019 documentation: https://developer.arm.com/docs/101028/latest
Reviewed by: David Spickett
Differential Revision: https://reviews.llvm.org/D60486
llvm-svn: 358963
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Summary:
The basic idea here is to make it possible to use
MachineInstr::mayAlias also when the MachineInstr
is const (or the "Other" MachineInstr is const).
The addition of const in MachineInstr::mayAlias
then rippled down to the need for adding const
in several other places, such as
TargetTransformInfo::getMemOperandWithOffset.
Reviewers: hfinkel
Reviewed By: hfinkel
Subscribers: hfinkel, MatzeB, arsenm, jvesely, nhaehnle, hiraditya, javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60856
llvm-svn: 358744
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Rename the functions that query the optimization kind attributes.
Differential revision: https://reviews.llvm.org/D60287
llvm-svn: 357731
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Cleanup isAArch64FrameOffsetLegal by:
- Merging the large switch statement to reuse AArch64InstrInfo::getMemOpInfo().
- Using AArch64InstrInfo::getUnscaledLdSt() to determine whether an instruction
has an unscaled variant.
- Simplifying the logic that calculates the offset to fit the immediate.
Reviewers: paquette, evandro, eli.friedman, efriedma
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D59636
llvm-svn: 357064
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This patch also adds cases PRFUMi and PRFMui.
This change was discussed in https://reviews.llvm.org/D59635.
llvm-svn: 357059
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When doing 128-bit atomics using CASP we might need to copy a GPRPair to a
different register, but that was unimplemented up to now.
llvm-svn: 353383
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We can't outline BTI instructions, because they need to be the very first
instruction executed after an indirect call or branch. If we outline them, then
an indirect call might go to the branch to the outlined function, which will
fault.
Differential revision: https://reviews.llvm.org/D57753
llvm-svn: 353190
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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
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Summary:
D55896 and D56029 add support to emit fixups for :abs_g0: , :abs_g1_s: , etc.
This patch adds the necessary enums and MCExpr needed for lowering these.
Reviewers: rnk, mstorsjo, efriedma
Reviewed By: efriedma
Subscribers: javed.absar, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D56037
llvm-svn: 350798
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This is an initial implementation for Speculative Load Hardening for
AArch64. It builds on top of the recently introduced
AArch64SpeculationHardening pass.
This doesn't implement (yet) some of the optimizations implemented for
the X86SpeculativeLoadHardening pass. I thought introducing the
optimizations incrementally in follow-up patches should make this easier
to review.
Differential Revision: https://reviews.llvm.org/D55929
llvm-svn: 350729
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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
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Refactor the scheduling predicates based on `MCInstPredicate`. In this
case, for the Exynos processors.
Differential revision: https://reviews.llvm.org/D55345
llvm-svn: 348774
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Fix predicate for arithmetic instructions with shift and/or extend.
llvm-svn: 348510
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llvm-svn: 348254
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This moves the stack check logic into a lambda within getOutliningCandidateInfo.
This allows us to be less conservative with stack checks. Whether or not a
stack instruction is safe to outline is dependent on the frame variant and call
variant of the outlined function; only in cases where we modify the stack can
these be unsafe.
So, if we move that logic later, when we're looking at an individual candidate,
we can make better decisions here.
This gives some code size savings as a result.
llvm-svn: 348220
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If we dropped too many candidates to be beneficial when dropping candidates
that modify the stack, there's no reason to check for other cost model
qualities.
llvm-svn: 348219
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If it's a bigger code size win to drop candidates that require stack fixups
than to demote every candidate to that variant, the outliner should do that.
This happens if the number of bytes taken by calls to functions that don't
require fixups, plus the number of bytes that'd be left is less than the
number of bytes that it'd take to emit a save + restore for all candidates.
Also add tests for each possible new behaviour.
- machine-outliner-compatible-candidates shows that when we have candidates
that don't use the stack, we can use the default call variant along with the
no save/regsave variant.
- machine-outliner-all-stack shows that when it's better to fix up the stack,
we still will demote all candidates to that case
- machine-outliner-drop-stack shows that we can discard candidates that
require stack fixups when it would be beneficial to do so.
llvm-svn: 348168
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If we know that we'll definitely save LR to a register, there's no reason to
pre-check whether or not a stack instruction is unsafe to fix up.
This makes it so that we check for that condition before mapping instructions.
This allows us to outline more, since we don't pessimise as many instructions.
Also update some tests, since we outline more.
llvm-svn: 348081
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Instead of treating the outlined functions for these as distinct frames, they
should be combined into one case. Neither allows for stack fixups, and both
generate the same frame. Thus, they ought to be considered one case.
This makes the code far easier to understand, for one thing. It also offers
some small code size improvements. It's fairly rare to see a class of outlined
functions that doesn't fall entirely into one variant (on CTMark anyway). It
does happen from time to time though.
This mostly offers some serious simplification.
Also update the test to show the added functionality.
llvm-svn: 348036
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It makes more sense to order FI-based memops in descending order when
the stack goes down. This allows offsets to stay "consecutive" and allow
easier pattern matching.
llvm-svn: 347906
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Before this patch, the following stores in `merge_fail` would fail to be
merged, while they would get merged in `merge_ok`:
```
void use(unsigned long long *);
void merge_fail(unsigned key, unsigned index)
{
unsigned long long args[8];
args[0] = key;
args[1] = index;
use(args);
}
void merge_ok(unsigned long long *dst, unsigned a, unsigned b)
{
dst[0] = a;
dst[1] = b;
}
```
The reason is that `getMemOpBaseImmOfs` would return false for FI base
operands.
This adds support for this.
Differential Revision: https://reviews.llvm.org/D54847
llvm-svn: 347747
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Currently, instructions doing memory accesses through a base operand that is
not a register can not be analyzed using `TII::getMemOpBaseRegImmOfs`.
This means that functions such as `TII::shouldClusterMemOps` will bail
out on instructions using an FI as a base instead of a register.
The goal of this patch is to refactor all this to return a base
operand instead of a base register.
Then in a separate patch, I will add FI support to the mem op clustering
in the MachineScheduler.
Differential Revision: https://reviews.llvm.org/D54846
llvm-svn: 347746
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Make the names for the macros for `TargetInstrInfo` uniform.
llvm-svn: 347706
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Refactor the scheduling predicates based on `MCInstPredicate`. In this
case, `AArch64InstrInfo::hasExtendedReg()`.
Differential revision: https://reviews.llvm.org/D54822
llvm-svn: 347599
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Refactor the scheduling predicates based on `MCInstPredicate`. In this
case, `AArch64InstrInfo::hasShiftedReg()`.
Differential revision: https://reviews.llvm.org/D54820
llvm-svn: 347598
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Refactor the scheduling predicates based on `MCInstPredicate`. In this
case, `AArch64InstrInfo::isScaledAddr()`
Differential revision: https://reviews.llvm.org/D54777
llvm-svn: 347597
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Using the MBB flags, we can tell if X16/X17/NZCV are unused in a block,
and also not live out.
If this holds for all MBBs, then we can avoid checking for liveness on
that candidate. Furthermore, if it holds for an individual candidate's
MBB, then we can avoid checking for liveness on that candidate.
llvm-svn: 346901
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If we keep track of if the ContainsCalls bit is set in the MBB flags for each
candidate, then we have a better chance of not checking the candidate for calls
at all.
This saves quite a few checks in some CTMark tests (~200 in Bullet, for
example.)
llvm-svn: 346816
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We already determine a bunch of information about an MBB in
getMachineOutlinerMBBFlags. We can reuse that information to avoid calculating
things that must be false/true.
The first thing we can easily check is if an outlined sequence could ever
contain calls. There's no reason to walk over the outlined range, checking for
calls, if we already know that there are no calls in the block containing the
sequence.
llvm-svn: 346809
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Since we never outline anything with fewer than 2 occurrences, there's no
reason to compute cost model information if there's less than that.
llvm-svn: 346803
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Turns out it's way simpler to do this check with one LRU. Instead of
maintaining two, just keep one. Check if each of the registers is available,
and then check if it's a live out from the block. If it's a live out, but
available in the block, we know we're in an unsafe case.
llvm-svn: 346721
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isMBBSafeToOutlineFrom
Instead of returning Flags, return true if the MBB is safe to outline from.
This lets us check for unsafe situations, like say, in AArch64, X17 is live
across a MBB without being defined in that MBB. In that case, there's no point
in performing an instruction mapping.
llvm-svn: 346718
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This patch adds support for funclets in frame lowering and ISel
lowering. Together with D50288 and D50166, it enables C++ exception
handling.
Patch by Sanjin Sijaric, with some fixes by me.
Differential Revision: https://reviews.llvm.org/D51524
llvm-svn: 346568
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Refactor helper functions in AArch64InstrInfo to be static methods.
llvm-svn: 346273
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Emit pseudo instructions indicating unwind codes corresponding to each
instruction inside the prologue/epilogue. These are used by the MCLayer to
populate the .xdata section.
Differential Revision: https://reviews.llvm.org/D50288
llvm-svn: 345701
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Prevents the post-RA scheduler from modifying the prologue sequences
emitting by frame lowering. This is roughly similar to what we do for
other targets: TargetInstrInfo::isSchedulingBoundary checks
isPosition(), which checks for CFI_INSTRUCTION.
isSEHInstruction is taken from D50288; it'll land with whatever patch
lands first.
Differential Revision: https://reviews.llvm.org/D53851
llvm-svn: 345634
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Effectively, NFC.
llvm-svn: 345201
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llvm-svn: 345188
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llvm-svn: 345187
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llvm-svn: 344774
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When branch target identification is enabled, we can only do indirect
tail-calls through x16 or x17. This means that the outliner can't
transform a BLR instruction at the end of an outlined region into a BR.
Differential revision: https://reviews.llvm.org/D52869
llvm-svn: 343969
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The MachineOutliner for AArch64 transforms indirect calls into indirect
tail calls, replacing the call with the TCRETURNri pseudo-instruction.
This pseudo lowers to a BR, but has the isCall and isReturn flags set.
The problem is that TCRETURNri takes a tcGPR64 as the register argument,
to prevent indiret tail-calls from using caller-saved registers. The
indirect calls transformed by the outliner could use caller-saved
registers. This is fine, because the outliner ensures that the register
is available at all call sites. However, this causes a verifier failure
when the register is not in tcGPR64. The fix is to add a new
pseudo-instruction like TCRETURNri, but which accepts any GPR.
Differential revision: https://reviews.llvm.org/D52829
llvm-svn: 343959
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This rebases and recommits r343520. hwasan should be fixed now and this
shouldn't break the tests anymore.
Spill/reload instructions are artificially generated by the compiler and
have no relation to the original source code. So the best thing to do is
not attach any debug location to them (instead of just taking the next
debug location we find on following instructions).
Differential Revision: https://reviews.llvm.org/D52125
llvm-svn: 343895
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- Fix spill/reloads of XSeqPairs failing with vregs (only physregs
worked correctly)
- Add missing spill/reload code for WSeqPairs class
Differential Revision: https://reviews.llvm.org/D52761
llvm-svn: 343799
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instructions"
This reverts r343520 due to breakage of HWASan tests on Android.
llvm-svn: 343616
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Spill/reload instructions are artificially generated by the compiler and
have no relation to the original source code. So the best thing to do is
not attach any debug location to them (instead of just taking the next
debug location we find on following instructions).
Differential Revision: https://reviews.llvm.org/D52125
llvm-svn: 343520
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