[semantic-arc] Attempt to handle indirect_mutating parameters that are never written to. #29480

gottesmm · 2020-01-27T22:04:47Z

It only handles local writes, so we can not handle chains of inout parameters.
That being said, I wonder if we could hook this up to an analysis to determine
if the inout has this same property in callees.

rdar://problem/58667192

Just had to get this out of my fingers.

gottesmm · 2020-01-27T22:04:59Z

@swift-ci smoke test

atrick

To handle calls, this can be converted into a bottom-up IPA... eventually...

Also, is there a possibility this will be called on the same argument multiple times? It's a red flag that you're calling an unbounded def-use analysis from within a use-def analysis.

atrick · 2020-01-27T23:32:18Z

lib/SILOptimizer/Mandatory/SemanticARCOpts.cpp

+    }
+
+    // load_borrow and debug_value_addr are both fine as well.
+    if (isa<LoadBorrowInst>(user) || isa<DebugValueAddrInst>(user)) {


When visiting uses, I like to use isIncidentalUse, instead of checking for Debug opcodes so we can add different "marker" instructions later without auditing all passes.

Yes. I was just writing something up real quickly. Also I realized I need to look through access markers.

atrick · 2020-01-27T23:40:42Z

lib/SILOptimizer/Mandatory/SemanticARCOpts.cpp

+    // interprocedural analysis that we do not perform here.
+    if (auto fas = FullApplySite::isa(user)) {
+      if (fas.getArgumentConvention(*op) ==
+          SILArgumentConvention::Indirect_In_Guaranteed)


Too bad you need to hard-code Full-Apply + Indirect_In_Guaranteed. I feel like we should be using the isMutatingOrConsuming logic from the verifier to handle closures, coroutines, and other conventions... but it looks like it returns an overly optimistic results for inout_aliasable

I was just trying to do something really simple. I am going to refactor it out.

gottesmm · 2020-01-28T00:15:50Z

@atrick I don't think this will be unbounded since it does not trigger the parent use-def walk in any way. We may perform the walk multiple times, but always a bounded amount of times.

gottesmm · 2020-01-28T00:18:42Z

From talking with Andy, he was actually referring to quadratic behavior.

atrick · 2020-01-28T00:22:19Z

When I say "unbounded" I mean there's nothing stopping it from running away on pathological code. You could have 1000 use-def walks in a pathological case, which is ok, but then then same def-use chain will be visited again.. quadratically

gottesmm · 2020-01-28T00:29:01Z

@swift-ci smoke test

gottesmm · 2020-01-28T00:29:07Z

@swift-ci smoke test

gottesmm · 2020-01-28T00:30:45Z

@swift-ci benchmark

gottesmm · 2020-01-28T00:30:48Z

@swift-ci benchmark

gottesmm · 2020-01-28T00:31:18Z

@swift-ci benchmark

swift-ci · 2020-01-28T00:52:29Z

Build failed before running benchmark.

gottesmm · 2020-01-28T00:52:32Z

@swift-ci test

gottesmm · 2020-01-28T00:52:38Z

@swift-ci smoke test

gottesmm · 2020-01-28T00:52:42Z

@swift-ci smoke test

gottesmm · 2020-01-28T00:52:46Z

@swift-ci smoke test

gottesmm · 2020-01-28T00:53:06Z

@swift-ci smoke test

swift-ci · 2020-01-28T00:54:43Z

Build failed
Swift Test OS X Platform
Git Sha - 40a773030b01b98b8dfcdae517f0f4b3020b74fe

swift-ci · 2020-01-28T00:54:58Z

Build failed
Swift Test Linux Platform
Git Sha - 40a773030b01b98b8dfcdae517f0f4b3020b74fe

gottesmm · 2020-01-28T01:05:28Z

Going to do a little more work on this real quick in the background and make sure at least when building the stdlib, I am not missing anything.

gottesmm · 2020-01-28T01:21:13Z

@swift-ci smoke test

gottesmm · 2020-01-28T01:21:18Z

@swift-ci smoke test

gottesmm · 2020-01-28T01:21:23Z

@swift-ci smoke test

gottesmm · 2020-01-28T01:22:05Z

@swift-ci smoke test

gottesmm · 2020-01-28T01:22:13Z

@swift-ci benchmark

gottesmm · 2020-01-28T01:22:17Z

@swift-ci benchmark

gottesmm · 2020-01-28T01:22:26Z

@swift-ci benchmark

gottesmm · 2020-01-28T01:22:35Z

@swift-ci benchmark

gottesmm · 2020-01-28T01:22:50Z

@swift-ci benchmark

gottesmm · 2020-01-28T01:23:42Z

@swift-ci benchmark

swift-ci · 2020-01-28T02:13:58Z

Performance: -O

Regression	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	4102	5049	+23.1%	0.81x (?)

Improvement	OLD	NEW	DELTA	RATIO
NSStringConversion.Long	570	503	-11.8%	1.13x (?)
ObjectiveCBridgeStubNSDateRefAccess	196	174	-11.2%	1.13x (?)
RemoveWhereMoveInts	19	17	-10.5%	1.12x (?)
RandomShuffleLCG2	464	416	-10.3%	1.12x (?)
ArrayPlusEqualFiveElementCollection	4773	4292	-10.1%	1.11x (?)
StringHashing_fastPrenormal	600	540	-10.0%	1.11x (?)
NormalizedIterator_fastPrenormal	630	570	-9.5%	1.11x
Calculator	143	130	-9.1%	1.10x (?)
MapReduce	218	200	-8.3%	1.09x (?)
RemoveWhereSwapInts	38	35	-7.9%	1.09x (?)
Set.isSubset.Int.Empty	52	48	-7.7%	1.08x (?)
ArraySetElement	283	262	-7.4%	1.08x
DropLastSequence	320	298	-6.9%	1.07x (?)

Code size: -O

Performance: -Osize

Regression	OLD	NEW	DELTA	RATIO
Set.isStrictSubset.Int.Empty	47	51	+8.5%	0.92x (?)
ArrayAppendLazyMap	4170	4520	+8.4%	0.92x (?)

Improvement	OLD	NEW	DELTA	RATIO
ArrayLiteral2	115	100	-13.0%	1.15x (?)
NormalizedIterator_fastPrenormal	640	570	-10.9%	1.12x (?)
StringHashing_fastPrenormal	600	540	-10.0%	1.11x (?)
NormalizedIterator_latin1	222	202	-9.0%	1.10x (?)
NSStringConversion.Long	549	503	-8.4%	1.09x (?)

Code size: -Osize

Improvement	OLD	NEW	DELTA	RATIO
ArraySetElement.o	1227	1212	-1.2%	1.01x
Sim2DArray.o	1259	1244	-1.2%	1.01x
COWArrayGuaranteedParameterOverhead.o	1334	1319	-1.1%	1.01x

Performance: -Onone

Improvement	OLD	NEW	DELTA	RATIO
PopFrontArray	1960	1580	-19.4%	1.24x
Hanoi	14830	12490	-15.8%	1.19x (?)
ArrayAppendLatin1	12818	11050	-13.8%	1.16x (?)
ArrayAppendAscii	12852	11084	-13.8%	1.16x (?)
ArrayAppendUTF16	12886	11186	-13.2%	1.15x (?)
PopFrontArrayGeneric	3440	3060	-11.0%	1.12x (?)
ArrayOfGenericRef	7300	6660	-8.8%	1.10x (?)
ArrayOfRef	7150	6530	-8.7%	1.09x (?)
ArrayOfGenericPOD2	815	752	-7.7%	1.08x (?)
NormalizedIterator_fastPrenormal	950	880	-7.4%	1.08x (?)

Code size: -swiftlibs

How to read the data

The tables contain differences in performance which are larger than 8% and differences in code size which are larger than 1%.

If you see any unexpected regressions, you should consider fixing the
regressions before you merge the PR.

Noise: Sometimes the performance results (not code size!) contain false
alarms. Unexpected regressions which are marked with '(?)' are probably noise.
If you see regressions which you cannot explain you can try to run the
benchmarks again. If regressions still show up, please consult with the
performance team (@eeckstein).

Hardware Overview

  Model Name: Mac mini
  Model Identifier: Macmini8,1
  Processor Name: Intel Core i7
  Processor Speed: 3.2 GHz
  Number of Processors: 1
  Total Number of Cores: 6
  L2 Cache (per Core): 256 KB
  L3 Cache: 12 MB
  Memory: 64 GB

gottesmm · 2020-02-02T22:02:43Z

I am going to clean up this a bit to get rid of the quadratic behavior and then in a follow on commit, I am going to add support for handling more complex cases including cases where the value is written to but not in the region we are loading within. I have a simple implementation that should work.

…e never written to. It only handles local writes, so we can not handle chains of inout parameters. That being said, I wonder if we could hook this up to an analysis to determine if the inout has this same property in callees.

gottesmm · 2020-02-03T03:36:03Z

@swift-ci test

gottesmm · 2020-02-03T03:36:06Z

@swift-ci test

gottesmm · 2020-02-03T03:36:08Z

@swift-ci test

gottesmm · 2020-02-03T03:36:16Z

@swift-ci test source compatibility

gottesmm · 2020-02-03T03:36:24Z

@swift-ci benchmark

gottesmm · 2020-02-03T03:36:28Z

@swift-ci test

gottesmm · 2020-02-03T03:36:35Z

@swift-ci test windows platform

gottesmm · 2020-02-03T03:36:40Z

@swift-ci benchmark

gottesmm · 2020-02-03T03:36:48Z

@swift-ci test source compatibility

gottesmm · 2020-02-03T03:36:56Z

@swift-ci test windows platform

swift-ci · 2020-02-03T04:30:10Z

Performance: -O

Improvement	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	9599	6962	-27.5%	1.38x (?)
FlattenListLoop	5117	3955	-22.7%	1.29x (?)
CharacterLiteralsLarge	108	97	-10.2%	1.11x
RandomShuffleLCG2	768	704	-8.3%	1.09x (?)
Array2D	7520	6944	-7.7%	1.08x (?)
MapReduceClass2	40	37	-7.5%	1.08x (?)
RemoveWhereSwapInts	67	62	-7.5%	1.08x (?)
ArrayPlusEqualFiveElementCollection	8436	7807	-7.5%	1.08x (?)
ObjectiveCBridgeStubNSDateRefAccess	400	371	-7.2%	1.08x (?)
MapReduceAnyCollection	397	369	-7.1%	1.08x (?)
MapReduce	400	372	-7.0%	1.08x

Code size: -O

Performance: -Osize

Regression	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	6888	7531	+9.3%	0.91x (?)

Improvement	OLD	NEW	DELTA	RATIO
String.replaceSubrange.RepChar.Small	391	355	-9.2%	1.10x (?)
NSStringConversion.LongUTF8	585	539	-7.9%	1.09x (?)
ObjectiveCBridgeStubFromNSDateRef	4010	3710	-7.5%	1.08x (?)

Code size: -Osize

Improvement	OLD	NEW	DELTA	RATIO
ArraySetElement.o	1227	1212	-1.2%	1.01x
Sim2DArray.o	1259	1244	-1.2%	1.01x
COWArrayGuaranteedParameterOverhead.o	1334	1319	-1.1%	1.01x

Performance: -Onone

Improvement	OLD	NEW	DELTA	RATIO
PopFrontArray	3500	2980	-14.9%	1.17x (?)
FatCompactMap	491850	420500	-14.5%	1.17x (?)
FindString.Rec3.Substring	1054	903	-14.3%	1.17x (?)
LazilyFilteredArrays2	133800	115200	-13.9%	1.16x (?)
Hanoi	22060	19050	-13.6%	1.16x (?)
FindString.Rec3.String	1070	937	-12.4%	1.14x (?)
LazilyFilteredArrayContains	1380100	1210500	-12.3%	1.14x (?)
ArrayAppendAscii	21114	18632	-11.8%	1.13x (?)
ArrayAppendLatin1	21046	18700	-11.1%	1.13x (?)
ArrayAppendUTF16	20876	18564	-11.1%	1.12x
ChainedFilterMap	343773	306594	-10.8%	1.12x (?)
StringUTF16SubstringBuilder	18770	16770	-10.7%	1.12x (?)
String.replaceSubrange.RepChar.Small	397	359	-9.6%	1.11x (?)
Histogram	8873	8063	-9.1%	1.10x (?)
ArrayOfRef	9500	8650	-8.9%	1.10x (?)
ArrayOfGenericRef	9600	8760	-8.7%	1.10x (?)
PopFrontArrayGeneric	5960	5440	-8.7%	1.10x (?)
FlattenListFlatMap	266394	243526	-8.6%	1.09x (?)
RangeReplaceableCollectionPlusDefault	7272	6672	-8.3%	1.09x (?)
ArrayOfPOD	1125	1038	-7.7%	1.08x (?)
ArrayPlusEqualSingleElementCollection	204591	189974	-7.1%	1.08x (?)
ArrayPlusEqualFiveElementCollection	163503	151996	-7.0%	1.08x (?)
ArrayAppendAsciiSubstring	50004	46620	-6.8%	1.07x (?)

Code size: -swiftlibs

How to read the data

The tables contain differences in performance which are larger than 8% and differences in code size which are larger than 1%.

If you see any unexpected regressions, you should consider fixing the
regressions before you merge the PR.

Noise: Sometimes the performance results (not code size!) contain false
alarms. Unexpected regressions which are marked with '(?)' are probably noise.
If you see regressions which you cannot explain you can try to run the
benchmarks again. If regressions still show up, please consult with the
performance team (@eeckstein).

Hardware Overview

  Model Name: Mac Pro
  Model Identifier: MacPro6,1
  Processor Name: 12-Core Intel Xeon E5
  Processor Speed: 2.7 GHz
  Number of Processors: 1
  Total Number of Cores: 12
  L2 Cache (per Core): 256 KB
  L3 Cache: 30 MB
  Memory: 64 GB

atrick reviewed Jan 27, 2020

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gottesmm force-pushed the pr-53b63ed55998c4245196c9d026b31c41598abb2e branch from 40a7730 to ac486a1 Compare January 28, 2020 00:28

gottesmm force-pushed the pr-53b63ed55998c4245196c9d026b31c41598abb2e branch from ac486a1 to 79b77f2 Compare January 28, 2020 00:52

gottesmm force-pushed the pr-53b63ed55998c4245196c9d026b31c41598abb2e branch from 79b77f2 to 0f924f0 Compare January 28, 2020 01:05

gottesmm force-pushed the pr-53b63ed55998c4245196c9d026b31c41598abb2e branch 2 times, most recently from 8da4eed to a4bf2c1 Compare January 28, 2020 01:21

gottesmm changed the title ~~[DRAFT][semantic-arc] Attempt to handle indirect_mutating parameters that are never written to.~~ [semantic-arc] Attempt to handle indirect_mutating parameters that are never written to. Feb 3, 2020

gottesmm force-pushed the pr-53b63ed55998c4245196c9d026b31c41598abb2e branch from a4bf2c1 to f9b0f99 Compare February 3, 2020 03:35

gottesmm mentioned this pull request Feb 3, 2020

[semantic-arc-opts] Convert @owned -> @guaranteed args of transforming terminators when fed by load [copy], copy_value. #29605

Merged

gottesmm merged commit 9ce20c4 into swiftlang:master Feb 3, 2020

gottesmm deleted the pr-53b63ed55998c4245196c9d026b31c41598abb2e branch February 3, 2020 12:27

gottesmm mentioned this pull request Mar 6, 2020

[SR-11706] Invoking computed properties on class-backed structures emits excessive retains/releases #54114

Open

[semantic-arc] Attempt to handle indirect_mutating parameters that are never written to. #29480

[semantic-arc] Attempt to handle indirect_mutating parameters that are never written to. #29480

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