All,
Looking for some guidance on narrowing down an issue I am seeing at
work. Some background: large monorepo, many packages; I'm on MacOS
Tahoe (26.6).
I have a problematic module that causes GHC to allocate a HUGE amount
of memory under certain conditions. Compilation never finishes -
instead, the process is killed by the OS.
* With -O1, GHC consumes a huge amount of memory (> 32GB) before
getting killed by the OS.
* Without -O1, but with all available -f flags that seemed to be
implied by -O1, GHC does NOT blow up and compilation succeeds. (List
of flags below.)
The last output (with -ddump-phases) in the failing case is always
"*** Specialise [aaa.Tests.Service.Client.TestHelpers]:" followed by a
newline, then nothing else.
I'm working to isolate the code that's causing the problem, to get to
a repro case, but in the meantime can anyone suggest why -O1 fails but
all the -f flags do not?
Thank you!
p.s. I'm happy to share logs but don't want to spam the list if those
aren't necessary.
**********
Here are all the flags I used in place of -O1:
-fblock-layout-cfg
-fcall-arity
-fcase-folding
-fcase-merge
-fcore-constant-folding
-fcmm-control-flow
-fcmm-elim-common-blocks
-fcmm-sink
-fcmm-static-pred
-fcore-constant-folding
-fcpr-anal
-fcross-module-specialise
-fcse
-fenable-rewrite-rules
-fexitification
-ffloat-in
-ffull-laziness
-fignore-asserts
-finline-generics
-floopification
-fnum-constant-folding
-fsolve-constant-dicts
-fspecialise
-fstg-cse
-fstrictness
-funbox-small-strict-fields
-fworker-wrapper
**********
Here is the (possibly) relevant logs for compilation with -O1 that failed:
*** Checking old interface for aaa.Tests.Service.Client.TestHelpers
(use -ddump-hi-diffs for more details):
[62 of 74] Compiling aaa.Tests.Service.Client.TestHelpers (
test/aaa/Tests/Service/Client/TestHelpers.hs,
/Users/xxx.yyy/Source/health-engine/well-he-aaa/worktrees/master/dist-newstyle/build/aarch64-osx/ghc-9.14.1/aaa-service-client-0.0.0/t/test/noopt/build/test/test-tmp/aaa/Tests/Service/Client/TestHelpers.o,
/Users/xxx.yyy/Source/health-engine/well-he-aaa/worktrees/master/dist-newstyle/build/aarch64-osx/ghc-9.14.1/aaa-service-client-0.0.0/t/test/noopt/build/test/test-tmp/aaa/Tests/Service/Client/TestHelpers.dyn_o
)
*** Parser [aaa.Tests.Service.Client.TestHelpers]:
!!! Parser [aaa.Tests.Service.Client.TestHelpers]: finished in 7.28
milliseconds, allocated 2.470 megabytes
*** Renamer/typechecker [aaa.Tests.Service.Client.TestHelpers]:
*** ConsistencyCheck [aaa.Tests.Service.Client.TestHelpers]:
!!! ConsistencyCheck [aaa.Tests.Service.Client.TestHelpers]: finished
in 1763.61 milliseconds, allocated 750.592 megabytes
!!! Renamer/typechecker [aaa.Tests.Service.Client.TestHelpers]:
finished in 2449.36 milliseconds, allocated 962.845 megabytes
*** Desugar [aaa.Tests.Service.Client.TestHelpers]:
Result size of Desugar (before optimization)
= {terms: 713, types: 33,167, coercions: 15,521, joins: 0/171}
Result size of Desugar (after optimization)
= {terms: 551, types: 27,957, coercions: 15,828, joins: 0/93}
!!! Desugar [aaa.Tests.Service.Client.TestHelpers]: finished in 5.46
milliseconds, allocated 2.524 megabytes
*** Simplifier [aaa.Tests.Service.Client.TestHelpers]:
Result size of Simplifier iteration=1
= {terms: 2,677, types: 74,181, coercions: 37,908, joins: 0/155}
Result size of Simplifier iteration=2
= {terms: 1,737, types: 52,195, coercions: 27,615, joins: 0/88}
Result size of Simplifier iteration=3
= {terms: 1,673, types: 51,005, coercions: 19,466, joins: 0/80}
Result size of Simplifier iteration=4
= {terms: 1,630, types: 50,531, coercions: 19,333, joins: 0/78}
Result size of Simplifier
= {terms: 1,630, types: 50,531, coercions: 19,333, joins: 0/78}
!!! Simplifier [aaa.Tests.Service.Client.TestHelpers]: finished in
217.38 milliseconds, allocated 120.723 megabytes
*** Specialise [aaa.Tests.Service.Client.TestHelpers]:
**********
Here are those same logs (up to specialisation) for a compilation that
succeeded (no -O1, only the -f flags):
*** Checking old interface for aaa.Tests.Service.Client.TestHelpers
(use -ddump-hi-diffs for more details):
[62 of 74] Compiling aaa.Tests.Service.Client.TestHelpers (
test/aaa/Tests/Service/Client/TestHelpers.hs,
/Users/xxx.yyy/Source/health-engine/well-he-aaa/worktrees/master/dist-newstyle/build/aarch64-osx/ghc-9.14.1/aaa-service-client-0.0.0/t/test/noopt/build/test/test-tmp/aaa/Tests/Service/Client/TestHelpers.o,
/Users/xxx.yyy/Source/health-engine/well-he-aaa/worktrees/master/dist-newstyle/build/aarch64-osx/ghc-9.14.1/aaa-service-client-0.0.0/t/test/noopt/build/test/test-tmp/aaa/Tests/Service/Client/TestHelpers.dyn_o
)
*** Parser [aaa.Tests.Service.Client.TestHelpers]:
!!! Parser [aaa.Tests.Service.Client.TestHelpers]: finished in 5.70
milliseconds, allocated 2.470 megabytes
*** Renamer/typechecker [aaa.Tests.Service.Client.TestHelpers]:
*** ConsistencyCheck [aaa.Tests.Service.Client.TestHelpers]:
!!! ConsistencyCheck [aaa.Tests.Service.Client.TestHelpers]: finished
in 1707.88 milliseconds, allocated 749.094 megabytes
!!! Renamer/typechecker [aaa.Tests.Service.Client.TestHelpers]:
finished in 2305.51 milliseconds, allocated 959.358 megabytes
*** Desugar [aaa.Tests.Service.Client.TestHelpers]:
Result size of Desugar (before optimization)
= {terms: 713, types: 33,167, coercions: 15,521, joins: 0/171}
Result size of Desugar (after optimization)
= {terms: 551, types: 27,957, coercions: 15,828, joins: 0/93}
!!! Desugar [aaa.Tests.Service.Client.TestHelpers]: finished in 4.66
milliseconds, allocated 2.526 megabytes
*** Simplifier [aaa.Tests.Service.Client.TestHelpers]:
Result size of Simplifier iteration=1
= {terms: 555, types: 27,953, coercions: 15,828, joins: 0/93}
Result size of Simplifier
= {terms: 555, types: 27,953, coercions: 15,828, joins: 0/93}
!!! Simplifier [aaa.Tests.Service.Client.TestHelpers]: finished in
8.60 milliseconds, allocated 5.818 megabytes
*** Specialise [aaa.Tests.Service.Client.TestHelpers]:
Result size of Specialise
= {terms: 555, types: 27,953, coercions: 15,828, joins: 0/10}
!!! Specialise [aaa.Tests.Service.Client.TestHelpers]: finished in
3.98 milliseconds, allocated 2.227 megabytes
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