Imagine a loop of the form:
```
preheader:
%r = def
header:
bcc latch, inner
inner1:
..
inner2:
b latch
latch:
%r = subs %r
bcc header
```
It can be possible for code to spend a decent amount of time in the
header<->latch loop, not going into the inner part of the loop as much.
The greedy register allocator can prefer to spill _around_ %r though,
adding spills around the subs in the loop, which can be very detrimental
for performance. (The case I am looking at is actually a very deeply
nested set of loops that repeat the header<->latch pattern at multiple
different levels).
The greedy RA will apply a preference to spill to the IV, as it is live
through the header block. This patch attempts to add a heuristic to
prevent that in this case for variables that look like IVs, in a similar
regard to the extra spill weight that gets added to variables that look
like IVs, that are expensive to spill. That will mean spills are more
likely to be pushed into the inner blocks, where they are less likely to
be executed and not as expensive as spills around the IV.
This gives a 8% speedup in the exchange benchmark from spec2017 when
compiled with flang-new, whilst importantly stabilising the scores to be
less chaotic to other changes. Running ctmark showed no difference in
the compile time. I've tried to run a range of benchmarking for
performance, most of which were relatively flat not showing many large
differences. One matrix multiply case improved 21.3% due to removing a
cascading chains of spills, and some other knock-on effects happen which
usually cause small differences in the scores.
We adjust the insertion point at the BB top for spills/copies during RA
to ensure they are placed after the exec restore instructions required
for the divergent control flow execution. This is, however, required
only for the vector operations. The insertions for scalar registers can
still go to the BB top.
The original commit, and the comments in the code already provide sufficient
context. But for posterity, there's a tiny bit more that might be useful if
someone is digging here in the future:
> This is related to <rdar://problem/10318439> Lower invokes into terminating
> machine instructions.
>
> The return value from a function call is live in to that function call's
> landing pad. The landing pad is shared with a later call, and the variable is
> undef on the first exceptional edge.
>
> Our computation of the last legal split point gets confused because the
> return value is live-out from the calling block, and live-in to the landing
> pad, but it is not live on the edge itself.
>
> Fixed in r147911 and r147912.
This reverts commit a496c8be6e638ae58bb45f13113dbe3a4b7b23fd.
The workaround in c26dfc81e254c78dc23579cf3d1336f77249e1f6 should work
around the underlying problem with SUBREG_TO_REG.
And dependent commits.
Details in D150388.
This reverts commit 825b7f0ca5f2211ec3c93139f98d1e24048c225c.
This reverts commit 7a98f084c4d121244ef7286bc6503b6a181d446e.
This reverts commit b4a62b1fa546312d882fa12dfdcd015177d66826.
This reverts commit b7836d856206ec39509d42529f958c920368166b.
No conflicts in the code, few tests had conflicts in autogenerated CHECKs:
llvm/test/CodeGen/Thumb2/mve-float32regloops.ll
llvm/test/CodeGen/AMDGPU/fix-frame-reg-in-custom-csr-spills.ll
Reviewed By: alexfh
Differential Revision: https://reviews.llvm.org/D156381
Replacing D143754. Right now the LiveRangeSplitting during register allocation uses
TargetOpcode::COPY instruction for splitting. For AMDGPU target that creates a
problem as we have both vector and scalar copies. Vector copies perform a copy over
a vector register but only on the lanes(threads) that are active. This is mostly sufficient
however we do run into cases when we have to copy the entire vector register and
not just active lane data. One major place where we need that is live range splitting.
Allowing targets to use their own copy instructions(if defined) will provide a lot of
flexibility and ease to lower these pseudo instructions to correct MIR.
- Introduce getTargetCopyOpcode() virtual function and use if to generate copy in Live range
splitting.
- Replace necessary MI.isCopy() checks with TII.isCopyInstr() in register allocator pipeline.
Reviewed By: arsenm, cdevadas, kparzysz
Differential Revision: https://reviews.llvm.org/D150388
This is a helper function to very slightly simplify many calls to
MachineInstruction::getOperandNo.
Differential Revision: https://reviews.llvm.org/D143250
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
This was stored in LiveIntervals, but not actually used for anything
related to LiveIntervals. It was only used in one check for if a load
instruction is rematerializable. I also don't think this was entirely
correct, since it was implicitly assuming constant loads are also
dereferenceable.
Remove this and rely only on the invariant+dereferenceable flags in
the memory operand. Set the flag based on the AA query upfront. This
should have the same net benefit, but has the possible disadvantage of
making this AA query nonlazy.
Preserve the behavior of assuming pointsToConstantMemory implying
dereferenceable for now, but maybe this should be changed.
This reverts commit 7207373e1eb0dd419b4e13a5e2d0ca146ef9544e.
We found another RISC-V bug when landing D126048, and it has been fixed
by D127642 now.
Differential Revision: https://reviews.llvm.org/D126048
Spliter will try to extend a live range into `r` slot for a use operand,
that's works on most situaion, however that not work correctly when the operand
has tied to def, and the def operand is early clobber.
Give an example to demo what's wrong:
0 %0 = ...
16 early-clobber %0 = Op %0 (tied-def 0), ...
32 ... = Op %0
Before extend:
%0 = [0r, 0d) [16e, 32d)
The point we want to extend is 0d to 16e not 16r in this case, but if
we use 16r here we will extend nothing because that already contained
in [16e, 32d).
This patch add check for detect such case and adjust the extend point.
Detailed explanation for testcase: https://reviews.llvm.org/D126047
Reviewed By: MatzeB
Differential Revision: https://reviews.llvm.org/D126048
We may use several COPY instructions to copy the needed sub-registers
during split. But the way we split the lanes during the COPYs may be
different from the subranges of the old register. This would fail when we
extend the subranges of the new register because the LaneMasks do not
match exactly between subranges of new register and old register.
Since we are bundling the COPYs, I think there is no need to further refine the
subranges of the new register based on the set of LaneMasks of the inserted COPYs.
I am not sure if there will be further breaking cases. But as the subranges of
new register are created based on the LaneMasks of the subranges of old register,
it will be highly possible we will always find an exact LaneMask match.
We can think about how to make the extendPHIKillRanges() work for
subrange mask mismatch case if we meet more such cases in the future.
The test case was from D105065 by @arsenm.
Differential Revision: https://reviews.llvm.org/D107829
statepoint instruction uses tied-def registers to represent live gc value which
is use and def at the same time on a call.
At the same time invoke statepoint instruction is a last split point which can throw and
jump to landing pad.
As a result we have instructon which is last split point with tied-defs registers and
we need to teach Greedy RA to work with it.
The option -use-registers-for-gc-values-in-landing-pad controls whether statepoint lowering
will generate tied-defs for invoke statepoint and is off by default now.
To resolve all issues the following changes has been done.
1) Last Split point for invoke statepoint should be statepoint itself
If statepoint has a def it is a relocated gc pointer and it should be available in landing pad.
So we cannot split interval after statepoint at end of basic block.
2) Do not split interval on tied-def
If end of interval for overlap utility is a use which has tied-def we
should not split interval on this instruction due to in this case use
and def may have different registers and it breaks tied-def property.
3) Take into account Last Split Point for enterIntvAtEnd
If the use after Last Split Point is a def so it should be tied-def and
we can take the def of the tied-use as ParentVNI and thus
tied-use and tied-def will be live in resulting interval.
4) Handle the case when def is after LIP in InlineSpiller
If def of LI is after last insertion point of basic block we cannot hoist in this BB.
The example of such instruction is invoke statepoint where def represents the
relocated live gc pointer. Invoke is a last insertion point and its def is located after it.
In this case there is no place to insert spill and we bail out.
5) Fix removeBackCopies to account empty copies
RegAssignMap cannot hold empty interval, so do not set stop
to kill value if it produces empty interval.
This can happen if we remove back-copy and right before that we have another
back-copy.
For example, for parent %0 we can get
%1 = COPY %0
%2 = COPY %0
while we removing %2 we cannot set kill for %1 due to its empty.
6) Do not hoist copy to BB if its def is after LSP
If the parent def is a LastSplitPoint or later we cannot hoist copy to this basic block
because inserted copy (or re-materialization) will be located before the def.
All parts have been reviewed separately as follows:
https://reviews.llvm.org/D100747https://reviews.llvm.org/D100748https://reviews.llvm.org/D100750https://reviews.llvm.org/D100927https://reviews.llvm.org/D100945https://reviews.llvm.org/D101028
Reviewers: reames, rnk, void, MatzeB, wmi, qcolombet
Reviewed By: reames, qcolombet
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D101150
Pseudo probe are currently given a slot index like other regular instructions. This affects register pressure and lifetime weight computation because of enlarged lifetime length with pseudo probe instructions. As a consequence, program could get different code generated w/ and w/o pseudo probes. I'm closing the gap by excluding pseudo probes from stack index and downstream register allocation related passes.
Reviewed By: wmi
Differential Revision: https://reviews.llvm.org/D100334
VirtRegAuxInfo is an extensibility point, so the register allocator's
decision on which implementation to use should be communicated to the
other users - namely, LiveRangeEdit.
Differential Revision: https://reviews.llvm.org/D96898
Return the best covering index, and additional needed to complete the
mask. This logically belongs in TargetRegisterInfo, although I ended
up not needing it for why I originally split this out.
Following on from D87757 "[SplitKit] Only copy live lanes", it is
possible to split a live range at a point when none of its subranges
are live. This patch handles that case by inserting an implicit def
of the superreg.
Patch by Quentin Colombet!
Differential Revision: https://reviews.llvm.org/D88397
Following on from D87757 "[SplitKit] Only copy live lanes", in
SplitEditor::addDeadDef, when we're checking whether the parent live
interval has a subrange defining the same lanes, tolerate the case
where the parent subrange defines a superset of the lanes. This can
happen when the child subrange comes from SplitEditor::buildCopy
decomposing a partial copy into a sequence of subreg copies that cover
the required lanes.
Differential Revision: https://reviews.llvm.org/D88020
When splitting a live interval with subranges, only insert copies for
the lanes that are live at the point of the split. This avoids some
unnecessary copies and fixes a problem where copying dead lanes was
generating MIR that failed verification. The test case for this is
test/CodeGen/AMDGPU/splitkit-copy-live-lanes.mir.
Without this fix, some earlier live range splitting would create %430:
%430 [256r,848r:0)[848r,2584r:1) 0@256r 1@848r L0000000000000003 [848r,2584r:0) 0@848r L0000000000000030 [256r,2584r:0) 0@256r weight:1.480938e-03
...
256B undef %430.sub2:vreg_128 = V_LSHRREV_B32_e32 16, %20.sub1:vreg_128, implicit $exec
...
848B %430.sub0:vreg_128 = V_AND_B32_e32 %92:sreg_32, %20.sub1:vreg_128, implicit $exec
...
2584B %431:vreg_128 = COPY %430:vreg_128
Then RAGreedy::tryLocalSplit would split %430 into %432 and %433 just
before 848B giving:
%432 [256r,844r:0) 0@256r L0000000000000030 [256r,844r:0) 0@256r weight:3.066802e-03
%433 [844r,848r:0)[848r,2584r:1) 0@844r 1@848r L0000000000000030 [844r,2584r:0) 0@844r L0000000000000003 [844r,844d:0)[848r,2584r:1) 0@844r 1@848r weight:2.831776e-03
...
256B undef %432.sub2:vreg_128 = V_LSHRREV_B32_e32 16, %20.sub1:vreg_128, implicit $exec
...
844B undef %433.sub0:vreg_128 = COPY %432.sub0:vreg_128 {
internal %433.sub2:vreg_128 = COPY %432.sub2:vreg_128
848B }
%433.sub0:vreg_128 = V_AND_B32_e32 %92:sreg_32, %20.sub1:vreg_128, implicit $exec
...
2584B %431:vreg_128 = COPY %433:vreg_128
Note that the copy from %432 to %433 at 844B is a curious
bundle-without-a-BUNDLE-instruction that SplitKit creates deliberately,
and it includes a copy of .sub0 which is not live at this point, and
that causes it to fail verification:
*** Bad machine code: No live subrange at use ***
- function: zextload_global_v64i16_to_v64i64
- basic block: %bb.0 (0x7faed48) [0B;2848B)
- instruction: 844B undef %433.sub0:vreg_128 = COPY %432.sub0:vreg_128
- operand 1: %432.sub0:vreg_128
- interval: %432 [256r,844r:0) 0@256r L0000000000000030 [256r,844r:0) 0@256r weight:3.066802e-03
- at: 844B
Using real bundles with a BUNDLE instruction might also fix this
problem, but the current fix is less invasive and also avoids some
unnecessary copies.
https://bugs.llvm.org/show_bug.cgi?id=47492
Differential Revision: https://reviews.llvm.org/D87757
Also renamed the fields to follow style guidelines.
Accessors help with readability - weight mutation, in particular,
is easier to follow this way.
Differential Revision: https://reviews.llvm.org/D87725
Before this instruction supported output values, it fit fairly
naturally as a terminator. However, being a terminator while also
supporting outputs causes some trouble, as the physreg->vreg COPY
operations cannot be in the same block.
Modeling it as a non-terminator allows it to be handled the same way
as invoke is handled already.
Most of the changes here were created by auditing all the existing
users of MachineBasicBlock::isEHPad() and
MachineBasicBlock::hasEHPadSuccessor(), and adding calls to
isInlineAsmBrIndirectTarget or mayHaveInlineAsmBr, as appropriate.
Reviewed By: nickdesaulniers, void
Differential Revision: https://reviews.llvm.org/D79794
Summary:
Refactor LiveRangeCalc such that it is now split into two classes
The objective is to split all the "register specific" logic away
from LiveRangeCalc.
The two new classes created are:
- LiveRangeCalc - is meant as a generic class to compute and modify
live ranges in a generic way. This class should deal only with
SlotIndices and VNInfo objects.
- LiveIntervalCals - is meant to be equivalent to the old LiveRangeCalc.
It computes the liveness virtual registers tracked by a LiveInterval
object.
With this refactoring LiveRangeCalc can be used to implement tracking of
liveness of LiveRanges that represent other things than just registers.
Subscribers: MatzeB, qcolombet, mgorny, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76584
Summary:
This clang-tidy check is looking for unsigned integer variables whose initializer
starts with an implicit cast from llvm::Register and changes the type of the
variable to llvm::Register (dropping the llvm:: where possible).
Partial reverts in:
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
X86FixupLEAs.cpp - Some functions return unsigned and arguably should be MCRegister
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
HexagonBitSimplify.cpp - Function takes BitTracker::RegisterRef which appears to be unsigned&
MachineVerifier.cpp - Ambiguous operator==() given MCRegister and const Register
PPCFastISel.cpp - No Register::operator-=()
PeepholeOptimizer.cpp - TargetInstrInfo::optimizeLoadInstr() takes an unsigned&
MachineTraceMetrics.cpp - MachineTraceMetrics lacks a suitable constructor
Manual fixups in:
ARMFastISel.cpp - ARMEmitLoad() now takes a Register& instead of unsigned&
HexagonSplitDouble.cpp - Ternary operator was ambiguous between unsigned/Register
HexagonConstExtenders.cpp - Has a local class named Register, used llvm::Register instead of Register.
PPCFastISel.cpp - PPCEmitLoad() now takes a Register& instead of unsigned&
Depends on D65919
Reviewers: arsenm, bogner, craig.topper, RKSimon
Reviewed By: arsenm
Subscribers: RKSimon, craig.topper, lenary, aemerson, wuzish, jholewinski, MatzeB, qcolombet, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, wdng, nhaehnle, sbc100, jgravelle-google, kristof.beyls, hiraditya, aheejin, kbarton, fedor.sergeev, javed.absar, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, tpr, PkmX, jocewei, jsji, Petar.Avramovic, asbirlea, Jim, s.egerton, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65962
llvm-svn: 369041
When splitting a subrange we end up with two different subranges covering
two different, non overlapping, lanes.
As part of this splitting the VNIs of the original live-range need
to be dispatched to the subranges according to which lanes they are
actually defining.
Prior to this patch we were assuming that all values were defining
all lanes. This was wrong as demonstrated by llvm.org/PR40835.
Differential Revision: https://reviews.llvm.org/D59731
llvm-svn: 357032
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
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
Because we create a new kind of debug instruction, DBG_LABEL, we need to
check all passes which use isDebugValue() to check MachineInstr is debug
instruction or not. When expelling debug instructions, we should expel
both DBG_VALUE and DBG_LABEL. So, I create a new function,
isDebugInstr(), in MachineInstr to check whether the MachineInstr is
debug instruction or not.
This patch has no new test case. I have run regression test and there is
no difference in regression test.
Differential Revision: https://reviews.llvm.org/D45342
Patch by Hsiangkai Wang.
llvm-svn: 331844
See r331124 for how I made a list of files missing the include.
I then ran this Python script:
for f in open('filelist.txt'):
f = f.strip()
fl = open(f).readlines()
found = False
for i in xrange(len(fl)):
p = '#include "llvm/'
if not fl[i].startswith(p):
continue
if fl[i][len(p):] > 'Config':
fl.insert(i, '#include "llvm/Config/llvm-config.h"\n')
found = True
break
if not found:
print 'not found', f
else:
open(f, 'w').write(''.join(fl))
and then looked through everything with `svn diff | diffstat -l | xargs -n 1000 gvim -p`
and tried to fix include ordering and whatnot.
No intended behavior change.
llvm-svn: 331184
Example situation:
```
BB0:
%0 = ...
use %0
; ...
condjump BB1
jmp BB2
BB1:
%0 = ... ; rematerialized def from above (from earlier split step)
jmp BB2
BB2:
; ...
use %0
```
%0 will have a live interval with 3 value numbers (for the BB0, BB1 and
BB2 parts). Now SplitKit tries and succeeds in rematerializing the value
number in BB2 (This only works because it is a secondary split so
SplitKit is can trace this back to a single original def).
We need to recompute all live ranges affected by a value number that we
rematerialize. The case that we missed before is that when the value
that is rematerialized is at a join (Phi VNI) then we also have to
recompute liveness for the predecessor VNIs.
rdar://35699130
Differential Revision: https://reviews.llvm.org/D42667
llvm-svn: 324039
Headers/Implementation files should be named after the class they
declare/define.
Also eliminated an `#include "llvm/CodeGen/LiveIntervalAnalysis.h"` in
favor of `class LiveIntarvals;`
llvm-svn: 320546
As part of the unification of the debug format and the MIR format, print
MBB references as '%bb.5'.
The MIR printer prints the IR name of a MBB only for block definitions.
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)->getNumber\(\)/" << printMBBReference(*\1)/g'
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)\.getNumber\(\)/" << printMBBReference(\1)/g'
* find . \( -name "*.txt" -o -name "*.s" -o -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#([0-9]+)/%bb.\1/g'
* grep -nr 'BB#' and fix
Differential Revision: https://reviews.llvm.org/D40422
llvm-svn: 319665
As part of the unification of the debug format and the MIR format, avoid
printing "vreg" for virtual registers (which is one of the current MIR
possibilities).
Basically:
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E "s/%vreg([0-9]+)/%\1/g"
* grep -nr '%vreg' . and fix if needed
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E "s/ vreg([0-9]+)/ %\1/g"
* grep -nr 'vreg[0-9]\+' . and fix if needed
Differential Revision: https://reviews.llvm.org/D40420
llvm-svn: 319427
LLVM Coding Standards:
Function names should be verb phrases (as they represent actions), and
command-like function should be imperative. The name should be camel
case, and start with a lower case letter (e.g. openFile() or isFoo()).
Differential Revision: https://reviews.llvm.org/D40416
llvm-svn: 319168
