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Merged
merged 3 commits into from
Sep 16, 2025
Merged

Ownership support for LICM #84045

merged 3 commits into from
Sep 16, 2025

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MAJKFL
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@MAJKFL MAJKFL commented Sep 1, 2025 •
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This PR enables the new LICM pass to properly handle values with ownership. It adds support for the following instructions:

  • load_borrow
  • store [init]
  • load [take]
  • load [copy]
  • begin_borrow
  • store_borrow
  • begin_apply
  • store [assign]

@MAJKFL MAJKFL force-pushed the new-sil-licm-pass-copy-ownership branch from 865d153 to 9706745 Compare September 2, 2025 17:09
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MAJKFL commented Sep 2, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 4, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 5, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 5, 2025

@swift-ci apple silicon benchmark

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MAJKFL commented Sep 5, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 5, 2025

@swift-ci apple silicon benchmark

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MAJKFL commented Sep 5, 2025

@swift-ci Please test

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MAJKFL commented Sep 5, 2025

@swift-ci Please Test Source Compatibility Release

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MAJKFL commented Sep 8, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 8, 2025

@swift-ci apple silicon benchmark

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MAJKFL commented Sep 8, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 8, 2025

@swift-ci apple silicon benchmark

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MAJKFL commented Sep 8, 2025

@swift-ci Please Test Source Compatibility Release

nate-chandler
nate-chandler approved these changes Sep 8, 2025
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Nice!

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LoopInvariantCodeMotion.swift Outdated
for exitBlock in loop.exitBlocks {
assert(exitBlock.hasSinglePredecessor, "Exiting edge should not be critical.")

if let createdEndBorrow {
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Looks like a few more lines to clone instead of createEndBorrow for every exitBlock. Out of curiosity, why clone?

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I wanted to handle multiple loop exit blocks similarly as in sink, where move is followed by copy on remaining exit blocks. Though here, I think you’re right, it’s better to just use createEndBorrow. I changed it.

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LoopInvariantCodeMotion.swift
_ context: FunctionPassContext
) -> Bool {
guard endInstructions.allSatisfy({ loop.contains(block: $0.parentBlock)}) else {
guard endInstructions.allSatisfy({ loop.contains(block: $0.parentBlock) && !($0 is TermInst) }) else {
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What's an example of a TermInst that is a scope ending instruction? Do unreachables and other terminators along the availability boundary show up as scope ending users?

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The problem here is with branching instructions with phi parameters. They can be considered as scope ending instructions, but it’s not possible to hoist them.

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Ah, right. Thanks.

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LoopInvariantCodeMotion.swift
let exitBlocks = loop.exitBlocks
var changed = false

for exitBlock in exitBlocks {
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Why not sink instructions into dead-end blocks? Once value lifetimes are "complete", scope-ending instructions will be required in such dead-ends. If sinking them into dead-ends is causing a problem, though, ensuring such values' lifetimes are complete can be addressed later on.

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We’ve encountered quite a few bugs when trying to sink instructions into dead-ends, which I believe were primarily caused by other lifetimes not being ended properly there. I think it should be an easy fix in the future though, just removing this check.

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MAJKFL commented Sep 9, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 9, 2025

@swift-ci Please test

@MAJKFL MAJKFL force-pushed the new-sil-licm-pass-copy-ownership branch from 84a24a8 to 0b75a81 Compare September 10, 2025 15:28
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MAJKFL commented Sep 10, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 10, 2025

@swift-ci Please test

@MAJKFL MAJKFL marked this pull request as ready for review September 10, 2025 15:33
@MAJKFL MAJKFL requested a review from eeckstein as a code owner September 10, 2025 15:33
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MAJKFL commented Sep 12, 2025

@swift-ci Please test macOS Platform

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@swift-ci Please test Apple Silicon

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MAJKFL commented Sep 15, 2025

@swift-ci Please smoke test

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MAJKFL commented Sep 15, 2025

@swift-ci Please test

@MAJKFL MAJKFL merged commit a5c6156 into swiftlang:main Sep 16, 2025
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Hello, this PR appears to have regressed the bootstrapping bots resulting in a compiler SIL verification failure:
https://ci.swift.org/job/swift-bootstrap-ubuntu-24_04-x86_64/452/
https://ci.swift.org/job/swift-bootstrap-amazonlinux-2023-x86_64/197/
https://ci.swift.org/view/all/job/swift-bootstrap-freebsd-14-x86_64/724/

[2025-09-16T14:43:30.877Z] <unknown>:0: warning: using (deprecated) legacy driver, Swift installation does not contain swift-driver at: '/home/build-user/stages/stage1/usr/bin/swift-driver-new'
[2025-09-16T14:43:30.877Z] <unknown>:0: warning: option '-no-emit-module-separately-wmo' is only supported in swift-driver
[2025-09-16T14:43:30.877Z] Begin Error in Function: '$ss30_copySequenceToContiguousArrayys0dE0Vy7ElementQzGxSTRzlF19CompilerSwiftParser5LexerO06LexemeB0V_Tg5'
[2025-09-16T14:43:30.877Z] Found over consume?!
[2025-09-16T14:43:30.877Z] Value:   %49 = load_borrow %46 : $*BumpPtrAllocator      // users: %69, %68
[2025-09-16T14:43:30.877Z] Block: bb1
[2025-09-16T14:43:30.877Z] Consuming Users:
[2025-09-16T14:43:30.877Z]   end_borrow %49 : $BumpPtrAllocator              // id: %69
[2025-09-16T14:43:30.877Z] 
[2025-09-16T14:43:30.877Z] End Error in Function: '$ss30_copySequenceToContiguousArrayys0dE0Vy7ElementQzGxSTRzlF19CompilerSwiftParser5LexerO06LexemeB0V_Tg5'
[2025-09-16T14:43:30.877Z] Found ownership error?!
[2025-09-16T14:43:30.877Z] <unknown>:0: error: fatal error encountered during compilation; please submit a bug report (https://swift.org/contributing/#reporting-bugs)
[2025-09-16T14:43:30.877Z] <unknown>:0: note: triggering standard assertion failure routine
...
[2025-09-16T14:43:30.877Z] 1.	Swift version 6.3-dev (LLVM 82c14639a1e4d89, Swift a5c615652529771)
[2025-09-16T14:43:30.877Z] 2.	Compiling with effective version 5.10
[2025-09-16T14:43:30.877Z] 3.	While evaluating request ExecuteSILPipelineRequest(Run pipelines { PrepareOptimizationPasses, EarlyModulePasses, HighLevel,Function+EarlyLoopOpt, HighLevel,Module+StackPromote, MidLevel,Function, ClosureSpecialize, LowLevel,Function, LateLoopOpt, SIL Debug Info Generator } on SIL for SwiftParser)
[2025-09-16T14:43:30.877Z] 4.	While running pass #8938 SILFunctionTransform "OwnershipModelEliminator" on SILFunction "@$ss30_copySequenceToContiguousArrayys0dE0Vy7ElementQzGxSTRzlF19CompilerSwiftParser5LexerO06LexemeB0V_Tg5".
[2025-09-16T14:43:30.877Z]  for <<debugloc at "<compiler-generated>":0:0>>5.	Found verification error when verifying before lowering ownership. Please re-run with -sil-verify-all to identify the actual pass that introduced the verification error.
[2025-09-16T14:43:30.877Z] 6.	While verifying SIL function "@$ss30_copySequenceToContiguousArrayys0dE0Vy7ElementQzGxSTRzlF19CompilerSwiftParser5LexerO06LexemeB0V_Tg5".
[2025-09-16T14:43:30.877Z]  for <<debugloc at "<compiler-generated>":0:0>>Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):

MAJKFL added a commit to MAJKFL/swift that referenced this pull request Sep 17, 2025
@MAJKFL
Revert "Merge pull request swiftlang#84045 from MAJKFL/new-sil-licm-p…
d2cd281 
…ass-copy-ownership"

This reverts commit a5c6156, reversing
changes made to 2b6ea81.
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MAJKFL commented Sep 17, 2025

Thanks. I've opened a reversion PR here: #84348

MAJKFL added a commit that referenced this pull request Sep 18, 2025
@MAJKFL
Merge pull request #84348 from MAJKFL/revert-licm-ownership
c8b281c 
Revert "Merge pull request #84045 from MAJKFL/new-sil-licm-pass-copy-…
MAJKFL added a commit to MAJKFL/swift that referenced this pull request Sep 19, 2025
@MAJKFL
Reapply "Merge pull request swiftlang#84045 from MAJKFL/new-sil-licm-…
38f28c1 
…pass-copy-ownership"

This reverts commit d2cd281.
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@nate-chandler nate-chandler nate-chandler approved these changes

@eeckstein eeckstein Awaiting requested review from eeckstein eeckstein is a code owner

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@MAJKFL @AnthonyLatsis @etcwilde @nate-chandler