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Remove ReasoningBasedSimplifier from libyul

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Due to a design decision to move away from a bundled SMT solver,
ReasoningBasedSimplifier in its current form cannot be use any longer.
This is a necessary step to allow a unified way to call solvers using
only SMTLIB interface.

Since this optimization pass has always been marked as highly
experimental and never turned on by default, it should be OK to remove
it.
This commit is contained in:
Martin Blicha
2023-06-28 14:38:36 +02:00
parent c819243374
commit 29041c8101
23 changed files with 3 additions and 863 deletions
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docs/internals/optimizer.rst
-21
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@@ -316,7 +316,6 @@ Abbreviation Full name
``L`` :ref:`load-resolver`
``M`` :ref:`loop-invariant-code-motion`
``r`` :ref:`redundant-assign-eliminator`
``R`` :ref:`reasoning-based-simplifier` - highly experimental
``m`` :ref:`rematerialiser`
``V`` :ref:`SSA-reverser`
``a`` :ref:`SSA-transform`
@@ -330,10 +329,6 @@ Abbreviation Full name
Some steps depend on properties ensured by ``BlockFlattener``, ``FunctionGrouper``, ``ForLoopInitRewriter``.
For this reason the Yul optimizer always applies them before applying any steps supplied by the user.
The ReasoningBasedSimplifier is an optimizer step that is currently not enabled
in the default set of steps. It uses an SMT solver to simplify arithmetic expressions
and boolean conditions. It has not received thorough testing or validation yet and can produce
non-reproducible results, so please use with care!
Selecting Optimizations
-----------------------
@@ -863,22 +858,6 @@ Works best if the code is in SSA form.
Prerequisite: Disambiguator, ForLoopInitRewriter.
.. _reasoning-based-simplifier:
ReasoningBasedSimplifier
^^^^^^^^^^^^^^^^^^^^^^^^
This optimizer uses SMT solvers to check whether ``if`` conditions are constant.
- If ``constraints AND condition`` is UNSAT, the condition is never true and the whole body can be removed.
- If ``constraints AND NOT condition`` is UNSAT, the condition is always true and can be replaced by ``1``.
The simplifications above can only be applied if the condition is movable.
It is only effective on the EVM dialect, but safe to use on other dialects.
Prerequisite: Disambiguator, SSATransform.
Statement-Scale Simplifications
-------------------------------