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06651a24
by Rodrigo Mesquita at 2025-07-02T17:24:52+01:00
refact: Split InternalModBreaks out of ModBreaks
There are currently two competing ways of referring to a Breakpoint:
1. Using the Tick module + Tick index
2. Using the Info module + Info index
1. The Tick index is allocated during desugaring in `mkModBreaks`. It is
used to refer to a breakpoint associated to a Core Tick. For a given
Tick module, there are N Ticks indexed by Tick index.
2. The Info index is allocated during code generation (in StgToByteCode)
and uniquely identifies the breakpoints at runtime (and is indeed used
to determine which breakpoint was hit at runtime).
Why we need both is described by Note [Breakpoint identifiers].
For every info index we used to keep a `CgBreakInfo`, a datatype containing
information relevant to ByteCode Generation, in `ModBreaks`.
This commit splits out the `IntMap CgBreakInfo` out of `ModBreaks` into
a new datatype `InternalModBreaks`.
- The purpose is to separate the `ModBreaks` datatype, which stores
data associated from tick-level information which is fixed after
desugaring, from the unrelated `IntMap CgBreakInfo` information
accumulated during bytecode generation.
- We move `ModBreaks` to GHC.HsToCore.Breakpoints
The new `InternalModBreaks` simply combines the `IntMap CgBreakInfo`
with `ModBreaks`. After code generation we construct an
`InternalModBreaks` with the `CgBreakInfo`s we accumulated and the
existing `ModBreaks` and store that in the compiled BCO in `bc_breaks`.
- Note that we previously only updated the `modBreaks_breakInfo`
field of `ModBreaks` at this exact location, and then stored the
updated `ModBreaks` in the same `bc_breaks`.
- We put this new datatype in GHC.ByteCode.Breakpoints
The rest of the pipeline for which CgBreakInfo is relevant is
accordingly updated to also use `InternalModBreaks`
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c3f1b718
by Rodrigo Mesquita at 2025-07-02T17:24:52+01:00
cleanup: Use BreakpointIds in bytecode gen
Small clean up to use BreakpointId and InternalBreakpointId more
uniformly in bytecode generation rather than using Module + Ix pairs
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92555217
by Rodrigo Mesquita at 2025-07-04T13:02:15+01:00
ghci: Allocate BreakArrays at link time only
Previously, a BreakArray would be allocated with a slot for every tick
in a module at `mkModBreaks`, in HsToCore. However, this approach has
a few downsides:
- It interleaves interpreter behaviour (allocating arrays for
breakpoints) within the desugarer
- It is inflexible in the sense it is impossible for the bytecode
generator to add "internal" breakpoints that can be triggered at
runtime, because those wouldn't have a source tick. (This is relevant
for our intended implementation plan of step-out in #26042)
- It ties the BreakArray indices to the *tick* indexes, while at runtime
we would rather just have the *info* indexes (currently we have both
because BreakArrays are indexed by the *tick* one).
Paving the way for #26042 and #26064, this commit moves the allocation
of BreakArrays to bytecode-loading time -- akin to what is done for CCS
arrays.
Since a BreakArray is allocated only when bytecode is linked, if a
breakpoint is set (e.g. `:break 10`) before the bytecode is linked,
there will exist no BreakArray to trigger the breakpoint in.
Therefore, the function to allocate break arrays (`allocateBreakArrays`)
is exposed and also used in GHC.Runtime.Eval to allocate a break array
when a breakpoint is set, if it doesn't exist yet (in the linker env).
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fd87ea98
by Rodrigo Mesquita at 2025-07-07T11:58:44+01:00
Uniquely identify Breakpoints at runtime using internal breakpoint ids
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3a9ac3cd
by Rodrigo Mesquita at 2025-07-07T11:59:09+01:00
Figure out the GHCi Bits