[Git][ghc/ghc][wip/romes/12935] 5 commits: determinism: Cmm unique renaming pass

Fri Sep 13 16:06:13 UTC 2024

Rodrigo Mesquita pushed to branch wip/romes/12935 at Glasgow Haskell Compiler / GHC

Commits:
bec9f340 by Rodrigo Mesquita at 2024-09-13T16:53:09+01:00
determinism: Cmm unique renaming pass

To achieve object determinism, we need to prevent the non-deterministic
uniques from leaking into the object code. We can do this by
deterministically renaming the non-external uniques in the Cmm groups
that are yielded right after StgToCmm.

The key to deterministic renaming is observing that the order of
declarations, instructions, and data in the Cmm groups are already
deterministic (modulo other determinism bugs), regardless of the
uniques. We traverse the Cmm AST in this deterministic order and
rename the uniques, incrementally, in the order they are found, thus
making them deterministic. This renaming is guarded by
-fobject-determinism which is disabled by default for now.

This is one of the key passes for object determinism. Read about the
overview of object determinism and a more detailed explanation of this
pass in:
* Note [Object determinism]
* Note [Renaming uniques deterministically]

Significantly closes the gap to #12935

- - - - -
a96081f1 by Rodrigo Mesquita at 2024-09-13T16:53:09+01:00
determinism: DCmmGroup vs CmmGroup

Part of our strategy in producing deterministic objects, namely,
renaming all Cmm uniques in order, depend on the object code produced
having a deterministic order (say, A_closure always comes before
B_closure).

However, the use of LabelMaps in the Cmm representation invalidated this
requirement because the LabelMaps elements would already be in a
non-deterministic order (due to the original uniques), and the renaming
in sequence wouldn't work because of that non-deterministic order.

Therefore, we now start off with lists in CmmGroup (which preserve the
original order), and convert them into LabelMaps (for performance in the
code generator) after the uniques of the list elements have been
renamed.

See Note [DCmmGroup vs CmmGroup or: Deterministic Info Tables] and #12935.

- - - - -
45de906a by Rodrigo Mesquita at 2024-09-13T16:53:09+01:00
determinism: Don't print unique in pprFullName

This unique was leaking as part of the profiling description in info
tables when profiling was enabled, despite not providing information
relevant to the profile.

- - - - -
52c39590 by Rodrigo Mesquita at 2024-09-13T16:53:10+01:00
determinism: UDFM for distinct-constructor-tables

In order to produce deterministic objects when compiling with
-distinct-constructor-tables, we also have to update the data
constructor map to be backed by a deterministic unique map (UDFM) rather
than a non-deterministic one (UniqMap).

- - - - -
bea3b26c by Rodrigo Mesquita at 2024-09-13T17:05:46+01:00
determinism: InfoTableMap uniques in generateCgIPEStub

Fixes object determinism when using -finfo-table-map

Make sure to also deterministically rename the IPE map (as per Note
[Renaming uniques deterministically]), and to use a deterministic unique
supply when creating new labels for the IPE information to guarantee
deterministic objects when IPE information is requested.

Note that the Cmm group produced in generateCgIPEStub must /not/ be
renamed because renaming uniques is not idempotent, and the references
to the previously renamed code in the IPE Cmm group would be renamed
twice and become invalid references to non-existent symbols.

We do need to det-rename the InfoTableMap that is created in the
conversion from Core to Stg. This is not a problem since that map won't
refer any already renamed names (since it was created before the
renaming).

- - - - -

30 changed files:

- compiler/GHC/Cmm.hs
- compiler/GHC/Cmm/CLabel.hs
- compiler/GHC/Cmm/Dataflow/Graph.hs
- compiler/GHC/Cmm/Graph.hs
- compiler/GHC/Cmm/Info/Build.hs
- compiler/GHC/Cmm/LayoutStack.hs
- compiler/GHC/Cmm/Parser.y
- compiler/GHC/Cmm/Pipeline.hs
- compiler/GHC/Cmm/Switch.hs
- compiler/GHC/Cmm/ThreadSanitizer.hs
- + compiler/GHC/Cmm/UniqueRenamer.hs
- compiler/GHC/CmmToAsm/Reg/Liveness.hs
- compiler/GHC/Driver/Config/StgToCmm.hs
- compiler/GHC/Driver/Flags.hs
- compiler/GHC/Driver/GenerateCgIPEStub.hs
- compiler/GHC/Driver/Main.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/Stg/Debug.hs
- compiler/GHC/StgToCmm.hs
- compiler/GHC/StgToCmm/CgUtils.hs
- compiler/GHC/StgToCmm/Config.hs
- compiler/GHC/StgToCmm/InfoTableProv.hs
- compiler/GHC/StgToCmm/Monad.hs
- compiler/GHC/StgToCmm/Prof.hs
- compiler/GHC/StgToCmm/Utils.hs
- compiler/GHC/Types/IPE.hs
- compiler/GHC/Types/Name.hs
- compiler/GHC/Types/Unique.hs
- compiler/GHC/Types/Unique/DFM.hs
- compiler/GHC/Utils/Outputable.hs

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/d7091d6dea51df10ab5de2d0b815192c5bb7577e...bea3b26cfbc860d9de2afa337c1c07fc3d13364e

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