[IRGen] Propagate locally-cached metadata completion to transitive dependencies.

[nate-chandler]

When metadata record for a generic type is locally cached as ::Complete, the metadata is known to be complete in that scope. If it's for a generic type, being complete means that all of its recursive generic arguments are also complete.

Previously, though, that fact was not exploited. So a metadata record for such an argument which was originally obtained via an incomplete request would remain cached in that incomplete state even when a generic type in which it appeared as a generic argument was cached as complete. At worst, the result was a runtime call (checkMetadataState) to promote the complete the metadata record for the recursive argument.

Here, when a bound generic type's metadata is locally cached as complete, its recursive generic arguments are visited; for each such type for which a metadata record is already locally cached, the preexisting record is recached as complete.

[nate-chandler]

@swift-ci please apple silicon benchmark

[nate-chandler]

@swift-ci please test

[rjmccall]

Hmm. I think this is going to force abstract entries in the LocalTypeData cache to emitted (abstract in the sense of the LTDC, i.e. metadata that can cheaply be produced). We probably don't want that; it might have a lot of extra compile-time cost, even if LLVM can eliminate it later.

It might be easiest to just add a new operation on the LTDC, some sort of update-state-in-scope operation. The initial implementation can just affect concrete entries, but in principle we could also make this work with abstract entries by cloning the abstract path and then telling it to override the completeness.

[nate-chandler]

Fixed. Added an advanceStateInScope operation to LTDC. It looks for relevant cache entries and updates the cache accordingly. There are TODOs for the abstract case. If a relevant concrete entry is found (i.e. one whose dominance point dominates the active dominance point), it's used to produce a new cache entry whose dominance point is the active dominance point and whose state is the one specified.

[rjmccall]

It's sortof implied by the code, but please update the comment to talk about transitively-complete metadata rather than the vaguer "all of the metadata it references".

[nate-chandler]

Fixed.

[nate-chandler]

@swift-ci please apple silicon benchmark

[nate-chandler]

@swift-ci please test

[nate-chandler]

### Performance (arm64): -O

**Improvement**                       | **OLD** | **NEW** | **DELTA** | **RATIO**
:---                                  | ---:    | ---:    | ---:   | ---:     
Data.init.Sequence.511B.Count.I       | 19.648  | 17.384  | -11.5% | **1.13x (?)**
BufferFillFromSlice                   | 12.107  | 10.793  | -10.9% | **1.12x (?)**
Breadcrumbs.IdxToUTF16Range.longASCII | 10.308  | 9.37    | -9.1%  | **1.10x (?)**
ArrayAppendGenericStructs             | 977.5   | 891.111 | -8.8%  | **1.10x (?)**
SubstringFromLongStringGeneric2       | 20.263  | 18.697  | -7.7%  | **1.08x (?)**
NSStringConversion.Rebridge           | 75.643  | 69.914  | -7.6%  | **1.08x (?)**
String.replaceSubrange.RepChar        | 943.0   | 876.0   | -7.1%  | **1.08x (?)**
NSStringConversion                    | 295.714 | 274.75  | -7.1%  | **1.08x (?)**
StringFromLongWholeSubstring          | 2.169   | 2.016   | -7.1%  | **1.08x**

### Code size: -O


### Performance (arm64): -Osize

**Regression**                        | **OLD** | **NEW** | **DELTA** | **RATIO**
:---                                  | ---:    | ---:    | ---:   | ---:     
ObserverForwarderStruct               | 193.696 | 210.8   | +8.8%  | **0.92x (?)**
  | | | | 
**Improvement**                       | **OLD** | **NEW** | **DELTA** | **RATIO**
StringWithCString2                    | 0.002   | 0.0     | -66.7% | **3.00x**
String.replaceSubrange.RepChar        | 949.0   | 860.0   | -9.4%  | **1.10x (?)**
Breadcrumbs.IdxToUTF16Range.longASCII | 11.554  | 10.62   | -8.1%  | **1.09x**
SubstringFromLongStringGeneric2       | 20.271  | 18.707  | -7.7%  | **1.08x (?)**
NSStringConversion.Rebridge           | 75.688  | 69.9    | -7.6%  | **1.08x (?)**
NSStringConversion                    | 295.667 | 274.667 | -7.1%  | **1.08x (?)**
StringFromLongWholeSubstring          | 2.328   | 2.172   | -6.7%  | **1.07x**

### Code size: -Osize


### Performance (arm64): -Onone

**Regression**                        | **OLD**  | **NEW**  | **DELTA** | **RATIO**
:---                                  | ---:     | ---:     | ---:   | ---:     
CharacterLiteralsLarge                | 230.75   | 262.0    | +13.5% | **0.88x (?)**
SIMDRandomMask.Int8x64                | 11013.0  | 11854.0  | +7.6%  | **0.93x (?)**
  | | | | 
**Improvement**                       | **OLD**  | **NEW**  | **DELTA** | **RATIO**
ArrayAppendGenericStructs             | 766.667  | 455.0    | -40.7% | **1.68x (?)**
RawBuffer.1000.findFirst              | 55503.0  | 47703.0  | -14.1% | **1.16x**
DataCreateMedium                      | 101300.0 | 88400.0  | -12.7% | **1.15x (?)**
RawBuffer.1000.findLast               | 61712.0  | 53889.0  | -12.7% | **1.15x**
RawBuffer.128.findLast                | 8449.0   | 7451.0   | -11.8% | **1.13x (?)**
RawBuffer.7.findLast                  | 1144.0   | 1011.5   | -11.6% | **1.13x (?)**
RawBuffer.39.findFirst                | 2813.0   | 2509.0   | -10.8% | **1.12x (?)**
RawBuffer.39.findLast                 | 3092.0   | 2785.0   | -9.9%  | **1.11x (?)**
DataCreateSmall                       | 13380.0  | 12150.0  | -9.2%  | **1.10x (?)**
PrefixWhileSequenceLazy               | 6420.0   | 5840.0   | -9.0%  | **1.10x (?)**
PrefixWhileAnySequenceLazy            | 6491.0   | 5914.0   | -8.9%  | **1.10x (?)**
DropWhileAnySequence                  | 8542.0   | 7800.0   | -8.7%  | **1.10x (?)**
DropWhileSequence                     | 8293.0   | 7579.0   | -8.6%  | **1.09x (?)**
DropWhileSequenceLazy                 | 7835.0   | 7165.0   | -8.6%  | **1.09x (?)**
RawBuffer.7.findFirst                 | 1020.0   | 933.0    | -8.5%  | **1.09x (?)**
DropWhileAnySequenceLazy              | 7906.0   | 7252.0   | -8.3%  | **1.09x (?)**
DictionaryCompactMapValuesOfNilValue  | 6658.333 | 6123.529 | -8.0%  | **1.09x (?)**
String.replaceSubrange.RepChar        | 946.0    | 872.0    | -7.8%  | **1.08x (?)**
NSStringConversion                    | 330.5    | 307.5    | -7.0%  | **1.07x (?)**
Dict.FilterAllMatch.24k               | 107.565  | 100.08   | -7.0%  | **1.07x (?)**
DropFirstSequence                     | 5524.0   | 5140.0   | -7.0%  | **1.07x (?)**
Dict.FilterAllMatch.20k               | 90.111   | 83.857   | -6.9%  | **1.07x (?)**
DropFirstSequenceLazy                 | 5517.0   | 5137.0   | -6.9%  | **1.07x (?)**
Dict.FilterAllMatch.16k               | 72.625   | 67.636   | -6.9%  | **1.07x (?)**
Dict.FilterAllMatch.28k               | 127.5    | 118.762  | -6.9%  | **1.07x (?)**
ObjectiveCBridgeStringIsEqualAllSwift | 32.138   | 30.03    | -6.6%  | **1.07x (?)**

### Code size: -swiftlibs

[rjmccall]

This looks great!

[slavapestov]

Nice!