JIT: Expand runtime lookups in a late phase by EgorBo · Pull Request #81635 · dotnet/runtime

EgorBo · 2023-02-04T13:19:39Z

Closes#35551 and is a preparation for #81432

The main advantage of the late expansion is that we will be able to do CSE/Hoisting for such helpers, e.g.:

staticvoidTest<T>(){for(inti=0;i<100;i++)Callee<T>();}

Current codegen:

; Assembly listing for method Prog:Test[System.__Canon]()57pushrdi56pushrsi53pushrbx 4883EC30 subrsp,48 48894C2428 mov qword ptr [rsp+28H],rcx 488BF1 movrsi,rcx 33FF xoredi,edi 488B5E10 movrbx, qword ptr [rsi+10H];;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; loop startG_M000_IG03:  488B4B10 movrcx, qword ptr [rbx+10H] 4885C9 testrcx,rcx7402je SHORT G_M000_IG05 EB15 jmp SHORT G_M000_IG06G_M000_IG05:  488BCE movrcx,rsi 48BAB80C584EFC7F0000 movrdx,0x7FFC4E580CB8 E87E36A95F call CORINFO_HELP_RUNTIMEHANDLE_METHOD 488BC8 movrcx,raxG_M000_IG06:  FF159D932800 call[Prog:Callee[System.__Canon]():bool] FFC7 incedi 83FF64 cmpedi,100 7CD3 jl SHORT G_M000_IG03;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; loop end 4883C430 addrsp,48 5B poprbx 5E poprsi 5F poprdi C3 ret; Total bytes of code 74

We were not able to hoist the runtime lookup stuff out of loop while this PR fixes that.
New codegen:

; Assembly listing for method Prog:Test[System.__Canon]()G_M2205_IG01: 57pushrdi56pushrsi53pushrbx 4883EC30 subrsp,48 48894C2428 mov qword ptr [rsp+28H],rcxG_M2205_IG02:  33F6 xoresi,esi 488B5138 movrdx, qword ptr [rcx+38H] 488B7A10 movrdi, qword ptr [rdx+10H] 4885FF testrdi,rdi7405je SHORT G_M2205_IG04G_M2205_IG03:  488BDF movrbx,rdi EB12 jmp SHORT G_M2205_IG05G_M2205_IG04:  48BA20D3D3B5FC7F0000 movrdx,0x7FFCB5D3D320 ; global ptr E8A1D10F5F call CORINFO_HELP_RUNTIMEHANDLE_METHOD 488BD8 movrbx,rax;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; loop startG_M2205_IG05:  488BCB movrcx,rbx FF1595216000 call[Prog:Callee[System.__Canon]()] FFC6 incesi 83FE64 cmpesi,100 7CF0 jl SHORT G_M2205_IG05;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; loop endG_M2205_IG06:  4883C430 addrsp,48 5B poprbx 5E poprsi 5F poprdi C3 ret; Total bytes of code 74

The call is correctly hoisted

This is also required to do proper fix for @jkotas's suggestion in #81432 (comment)

Quite nice diffs

ghost · 2023-02-04T13:19:51Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch, @kunalspathak
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Issue Details

Closes #35551 and is a preparation for #81432

The main advantage of the late expansion is that we will be able to do CSE/Hoisting for such helpers, e.g.:

staticvoidTest<T>(){for(inti=0;i<100;i++)Callee<T>();}

Current codegen:

; Assembly listing for method Prog:Test[System.__Canon]()57pushrdi56pushrsi53pushrbx 4883EC30 subrsp,48 48894C2428 mov qword ptr [rsp+28H],rcx 488BF1 movrsi,rcx 33FF xoredi,edi 488B5E10 movrbx, qword ptr [rsi+10H] ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; loop startG_M000_IG03:  488B4B10 movrcx, qword ptr [rbx+10H] 4885C9 testrcx,rcx7402je SHORT G_M000_IG05 EB15 jmp SHORT G_M000_IG06G_M000_IG05:  488BCE movrcx,rsi 48BAB80C584EFC7F0000 movrdx,0x7FFC4E580CB8 E87E36A95F call CORINFO_HELP_RUNTIMEHANDLE_METHOD 488BC8 movrcx,raxG_M000_IG06:  FF159D932800 call[Prog:Callee[System.__Canon]():bool] FFC7 incedi 83FF64 cmpedi,100 7CD3 jl SHORT G_M000_IG03 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; loop end 4883C430 addrsp,48 5B poprbx 5E poprsi 5F poprdi C3 ret; Total bytes of code 74

We were not able to hoist the runtime lookup stuff out of loop while this PR fixes that.
This is also required to do proper fix for @jkotas's suggestion in #81432 (comment)

Author:	EgorBo
Assignees:	-
Labels:	`area-CodeGen-coreclr`
Milestone:	-

…lookups-later

AndyAyersMS · 2023-02-06T15:57:20Z

Presumably, the dynamically expandable ones can't be marked as "pure"

Right, they are not pure.

jakobbotsch · 2023-02-06T16:03:18Z

They might not be "pure" for a very strict sense of pure, but like the comment says, can they not be optimized as such from the JIT's perspective? I.e. they are idempotent.

AndyAyersMS · 2023-02-06T16:29:29Z

Well, there are (were?) issues like #40298. I vaguely recall some other problem but haven't pinned it down yet.

AndyAyersMS · 2023-02-06T16:36:23Z

Well, there are (were?) issues like #40298. I vaguely recall some other problem but haven't pinned it down yet.

Hmm. Maybe the other thing was just making sure we don't mark some of those indirs in the early expansions as invariant.

jkotas · 2023-02-06T17:44:22Z

The dictionary lookup as a whole is pure. The helper call to populate the dictionary slot lazily is not pure (ie it has observable side-effects).

…lookups-later

EgorBo · 2023-02-25T17:33:43Z

Fun fact about this PR - non-inlined runtime lookups lead to test timeouts. Initially I suspected some freezes/crashes but it turned out the code is just slow 😐

E.g. System.ObjectModel.Tests takes around a second to finish normally and 1 minutes without expanded runtime lookups

This reverts commit 22f34a1.

Co-authored-by: Jakob Botsch Nielsen <Jakob.botsch.nielsen@gmail.com>

EgorBo · 2023-03-14T18:25:12Z

Anything else? New diffs - TP is even better than previously for Tier0, thanks @jakobbotsch

jakobbotsch

LGTM!

AndyAyersMS

LGTM, just a few questions....

AndyAyersMS · 2023-03-14T19:58:05Z

+ BasicBlockFlags originalFlags = block->bbFlags;
+ BasicBlock* prevBb = block;
+
+ if (stmt == block->firstStmt())


This is checking for the case where gtSplitTree didn't do anything?
Perhaps deserves a comment to that effect.

I'll add a comment in a follow up if you don't mind to avoid re-running CI for it

Is this really about gtSplitTree? Isn't it here because we don't have a fgSplitBlockBefore?
gtSplitTree can make changes even without introducing new statements -- the return value needs to be used for that kind of check.

Yes, it's here just because I need basically fgSplitBlockBefore and only have fgSplitBlockAfter API

so when it's not the first statement in the current block I do fgSplitBlockAfter (stmt->PrevStmt())

I suppose I should look at what gtSplitTree does, but I'm still confused exactly what this method is supposed to be doing. Maybe an example would help?

I suppose I should look at what gtSplitTree does, but I'm still confused exactly what this method is supposed to be doing. Maybe an example would help?
The general idea that we want to split a block (e.g. BB0) into two (say, BBa and BBb) at a specific node (e.g. callX) and make sure that all side-effects are moved to BBa and the actual callX is now in BBb.
We have a phase where we insert GC safe points after specific call nodes - that one didn't have to care about any execution ordering since we just wanted to make sure GC is polled (it doesn't even matter whether to emit the poll before or after the calls). The runtime lookup case is a lot more complicated since we needed to insert verbose tree in front of the call and re-use its arguments, respect all kinds of complex COMMAs,

AndyAyersMS · 2023-03-14T20:05:10Z

+ }

- assert((lastIndOfTree != nullptr) && (pRuntimeLookup->indirections > 0));
+impSpillSideEffects(true, CHECK_SPILL_ALL DEBUGARG("bubbling QMark0"));


Is there any benefit to deferring expansion of the rest of this in a manner similar to the case above? Seems like this is also creating a hoistable/cseable complex.

I didn't touch this path because it wasn't clear for me when it's hit. From what I see it's not used by R2R and NAOT. Perhaps some dynamic context
In a follow I'll see if it's worth supporting

testForFixup was used by fragile NGen. It is not used anymore. I think it is fine to delete it - both on the JIT/EE interface and the supporting code in the JIT.

testForFixup was used by fragile NGen. It is not used anymore. I think it is fine to delete it - both on the JIT/EE interface and the supporting code in the JIT.
Thanks, will delete in #83430

EgorBo · 2023-03-21T12:52:07Z

Some CSE/Hoisting related Improvements on x64:

[Perf] Alpine/x64: 36 Improvements on 3/15/2023 12:03:45 AM perf-autofiling-issues#14217
[Perf] Linux/x64: 32 Improvements on 3/15/2023 12:03:45 AM perf-autofiling-issues#14211
[Perf] Windows/x86: 47 Improvements on 3/15/2023 12:03:45 AM perf-autofiling-issues#14244
[Perf] Windows/x64: 42 Improvements on 3/15/2023 12:03:45 AM perf-autofiling-issues#14277

Expand runtime lookups in a late phase
2dcd5e4

ghost added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Feb 4, 2023

ghost assigned EgorBo Feb 4, 2023

EgorBo commented Feb 4, 2023
View reviewed changes

Comment threadsrc/coreclr/jit/indirectcalltransformer.cpp

Clean up
2c7a4a3

This was referenced Feb 4, 2023
System.Text.RegularExpressions.Tests.AttRegexTests test fails in CI #75808
Closed
Test failure Loader\\classloader\\DictionaryExpansion\\DictionaryExpansion\\DictionaryExpansion.cmd #75244
Closed

jakobbotsch mentioned this pull request Feb 5, 2023
SPMI: Fix SpmiRecordsHelper::RestoreCORINFO_RUNTIME_LOOKUP #81657
Merged

Merge branch 'main' of github.com:dotnet/runtime into expand-runtime-…
5754331
…lookups-later

EgorBo mentioned this pull request Feb 6, 2023
Don't clone a large tree in impRuntimeLookupToTree #81472
Closed

test
dca8140

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test2
e303869

runfoappBot mentioned this pull request Feb 6, 2023
Infra improvements for Helix #68176
Closed

EgorBo added 4 commits February 25, 2023 11:29

Merge branch 'main' of github.com:dotnet/runtime into expand-runtime-…
aa760e5
…lookups-later

Test
20e79dc

Enable JitDasmWithAlignmentBoundaries in Release
22f34a1

Merge branch 'main' of github.com:dotnet/runtime into expand-runtime-…
c3681c1
…lookups-later

EgorBo added 5 commits February 25, 2023 19:05

clean up
2110ec0

Revert "Enable JitDasmWithAlignmentBoundaries in Release"
54b224c
This reverts commit 22f34a1.

add hashtable
e4d4944

test
3e272e0

Initial version (no dynamic expansion for now)
2671e14

Add goto SCAN_BLOCK_AGAIN
a116695

jakobbotsch reviewed Mar 14, 2023
View reviewed changes

Comment threadsrc/coreclr/jit/runtimelookup.cpp

EgorBoand others added 3 commits March 14, 2023 15:27

Update src/coreclr/jit/runtimelookup.cpp
386446e
Co-authored-by: Jakob Botsch Nielsen <Jakob.botsch.nielsen@gmail.com>

Address feedback
d2f3fec

update side effects for fallbackBb
19034d9

jakobbotsch approved these changes Mar 14, 2023
View reviewed changes

AndyAyersMS approved these changes Mar 14, 2023
View reviewed changes

EgorBo merged commit d86af84 into dotnet:mainMar 14, 2023

EgorBo deleted the expand-runtime-lookups-later branch March 14, 2023 22:33

EgorBo mentioned this pull request Mar 15, 2023
Runtime lookup clean up, enable for helper-based tail calls #83430
Merged

AndyAyersMS mentioned this pull request Mar 21, 2023
Regressions in System.Collections.CreateAddAndRemove #83738
Closed

kunalspathak mentioned this pull request Mar 21, 2023
[Perf] Linux/x64: 4 Improvements on 3/17/2023 5:15:23 PM dotnet/perf-autofiling-issues#14214
Closed

AndyAyersMS mentioned this pull request Mar 21, 2023
[Perf] Linux/x64: 18 Regressions on 3/15/2023 12:03:45 AM dotnet/perf-autofiling-issues#14193
Closed

EgorBo mentioned this pull request Mar 25, 2023
NativeAOT: Partially expand static initialization #83911
Merged

kunalspathak mentioned this pull request Mar 28, 2023
Consider expanding casts in late phases #84025
Open

AndyAyersMS mentioned this pull request Mar 30, 2023
JIT: better optimization for CORINFO_HELP_RUNTIMEHANDLE_METHOD #7590
Closed

JulieLeeMSFT mentioned this pull request Apr 4, 2023
What's new in .NET 8 Preview 3 dotnet/core#8135
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3 tasks

AndyAyersMS mentioned this pull request Apr 13, 2023
Regression in System.Collections.Concurrent.IsEmpty.Queue #84790
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