[opt] Automatically skip known-no-op passes in pipelines#4036
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[opt] Automatically skip known-no-op passes in pipelines#4036copybara-service[bot] wants to merge 1 commit intomainfrom
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If a pass is invoked twice on the same IR, and made no changes the first time, then we know it should make no changes the second time. Rather than rerunning the pass and any associated analyses, we can skip this entirely. To support this, we add the `GetInvocationSignature` method to `PassBase`, so passes can declare a unique signature including any options that affect how the pass runs. Any pass that does not declare an invocation signature will run every time. Certain passes are idempotent, meaning that if they're invoked twice in sequence, the second invocation will *always* be a no-op. We add the `IsIdempotent` method to let these passes opt into this stronger behavior. PiperOrigin-RevId: 879744536
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[opt] Automatically skip known-no-op passes in pipelines
If a pass is invoked twice on the same IR, and made no changes the first time, then we know it should make no changes the second time. Rather than rerunning the pass and any associated analyses, we can skip this entirely.
To support this, we add the
GetInvocationSignaturemethod toPassBase, so passes can declare a unique signature including any options that affect how the pass runs. Any pass that does not declare an invocation signature will run every time.Certain passes are idempotent, meaning that if they're invoked twice in sequence, the second invocation will always be a no-op. We add the
IsIdempotentmethod to let these passes opt into this stronger behavior.