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7495d449
by sheaf at 2026-04-15T01:10:40-04:00
Simplify mkTick
This commit simplifies 'GHC.Core.Utils.mkTick', removing the
accumulating parameter 'rest' which was suspiciously treating a bunch of
different ticks as a group, and moving the group as a whole around the
AST, ignoring that the ticks in the group might have different placement
properties.
The most important change is that we revert the logic (added in 85b0aae2)
that allowed ticks to be placed around coercions, which caused serious
issues (e.g. #27121). It was just a mistake, as it doesn't make sense
to put a tick around a coercion.
Also adds Note [Pushing SCCs inwards] which clarifies the logic for
pushing SCCs into lambdas, constructor applications, and dropping SCCs
around non-function variables (in particular the treatment of splittable
ticks).
A few other changes are also implemented:
- simplify 'can_split' predicate (no functional change)
- combine profiling ticks into one when possible
Fixes #26878, #26941 and #27121
Co-authored-by: simonpj <simon.peytonjones@gmail.com>
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760ff7b2
by Wolfgang Jeltsch at 2026-04-15T01:10:41-04:00
Move most of the `System.IO` implementation into `base`
This involves a rewrite of the `combine` helper function to avoid the
use of `last`, which would now be flagged as an error.
Metric Increase:
T12227
T12707
T5642
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9d643ef2
by Simon Jakobi at 2026-04-15T01:10:44-04:00
Add regression test for #9074
Closes #9074.
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63c2e2b1
by Rodrigo Mesquita at 2026-04-15T01:10:45-04:00
New rts Message to {set,unset} TSO flags
This commit introduces stg_MSG_SET_TSO_FLAG_info and
stg_MSG_UNSET_TSO_FLAG_info, which allows setting flags of a TSO other
than yourself.
This is especially useful/necessary to set breakpoints and toggle
breakpoints of different threads, which is needed to safely implement
features like pausing, toggling step-out, toggling step-in per thread,
etc.
Fixes #27131
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797a7e63
by Rodrigo Mesquita at 2026-04-15T01:10:45-04:00
test: Add test setting another TSO's flags
Introduces a test that runs on two capabilities. The main thread running
on Capability 0 sets the flags on a TSO running on Capability 1.
The TSO from Capability 1 itself checks whether its flags were set and
reports that back.
This validates that the RTS messages for setting TSO flags work, even if
it doesn't test a harsher scenario with race conditions to exercise why
the message passing is necessary for safely setting another TSO's flags.
Part of #27131
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c6021fc8
by Sylvain Henry at 2026-04-15T01:11:08-04:00
Add changelog for #15973
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a7b06eca
by sheaf at 2026-04-15T01:11:25-04:00
Deal with 'noSpec' in 'coreExprToPmLit'
This commit makes two separate changes relating to
'GHC.HsToCore.Pmc.Solver.Types.coreExprAsPmLit':
1. Commit 7124e4ad mistakenly marked deferred errors as non-canonical,
which led to the introduction of 'nospec' wrappers in the
generated Core. This reverts that accident by declaring deferred
errors as being canonical, avoiding spurious 'nospec' wrapping.
2. Look through magic identity-like Ids such as 'nospec', 'inline' and
'lazy' in 'coreExprAsPmLit', just like Core Prep does.
There might genuinely be incoherent evidence, but that shouldn't
obstruct the pattern match checker. See test T27124a.
Fixes #25926 #27124