Andrew Trick 38c29e231e Generalize and fix SinkAddressProjections. ...

Fixes a potential real bug in the case that SinkAddressProjections moves
projections without notifying SimplifyCFG of the change. This could
fail to update Analyses (probably won't break anything in practice).

Introduce SILInstruction::isPure. Among other things, this can tell
you if it's safe to duplicate instructions at their
uses. SinkAddressProjections should check this before sinking uses. I
couldn't find a way to expose this as a real bug, but it is a
theoretical bug.

Add the SinkAddressProjections functionality to the BasicBlockCloner
utility. Enable address projection sinking for all BasicBlockCloner
clients (the four different kinds of jump-threading that use it). This
brings the compiler much closer to banning all address phis.

The "bugs" were originally introduced a week ago here:

commit f22371bf0b (fork/fix-address-phi, fix-address-phi)
Author: Andrew Trick <atrick@apple.com>
Date:   Tue Sep 17 16:45:51 2019

    Add SIL SinkAddressProjections utility to avoid address phis.

    Enable this utility during jump-threading in SimplifyCFG.

    Ultimately, the SIL verifier should prevent all address-phis and we'll
    need to use this utility in a few more places.

    Fixes <rdar://problem/55320867> SIL verification failed: Unknown
    formal access pattern: storage

2019-11-14 16:11:00 -08:00

9.7 KiB

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