[all-commits] [llvm/llvm-project] 8d971c: Reapply "[TableGen] Introduce MatcherList to manag...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8d971c0360f91729cc5120ffd361f7b55e97f2ab
      https://github.com/llvm/llvm-project/commit/8d971c0360f91729cc5120ffd361f7b55e97f2ab
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2026-02-14 (Sat, 14 Feb 2026)

  Changed paths:
    M llvm/utils/TableGen/DAGISelEmitter.cpp
    M llvm/utils/TableGen/DAGISelMatcher.cpp
    M llvm/utils/TableGen/DAGISelMatcher.h
    M llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
    M llvm/utils/TableGen/DAGISelMatcherGen.cpp
    M llvm/utils/TableGen/DAGISelMatcherOpt.cpp

  Log Message:
  -----------
  Reapply "[TableGen] Introduce MatcherList to manage a linked list of Matchers. NFC (#177875)"

With fixes to the slice_after functions to avoid dereferencing the
before_begin() iterator. Deferencing the iterator casts a pointer
to the BeforeBegin object to Matcher*, but the BeforeBegin object
is not a Matcher. This caused a failure when built with gcc.

Original commit message:

The previous memory management involved passing around references to the
std::unique_ptr next pointer in each Matcher. Scopes and
SwitchOpcode/SwitchType did not use std::unique_ptr internally, but
would sometimes need to have the pointers to their children moved to
temporary std::unique_ptrs that may be modified and then put back into
the Scope/Switch. Other code used manual deletion.

This patch introduces a MatcherList object that encapsulates list
management and ownership. The interface is based on std::forward_list
using the libcxx implementation for reference.

Once a Matcher is added to a MatcherList it can only be in that list or
spliced into another list. This ensures it is always owned by a list
that will be responsible for deleting it.

Scope and SwitchOpcode/Type children are now MatcherLists rather than
Matcher*. A nice side effect of this is that we no longer need a Size
field in each Matcher to store the size of Scope/Switch children during
emission. This field was only used for the Matcher that the Scope/Switch
children pointed to. Now we can store it in the MatcherList instead.

There is no change to the generated output.

There's still a little bit of cleanup that can be done in follow ups. For example,
renaming "TheMatcher" and merging FactorScope and FactorNodes together.



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