SCCP can use PredicateInfo to constrain ranges based on assume and
branch conditions. Currently, this is only enabled during IPSCCP.
This enables it for SCCP as well, which runs after functions have
already been simplified, while IPSCCP runs pre-inline. To a large
degree, CVP already handles range-based optimizations, but SCCP is more
reliable for the cases it can handle. In particular, SCCP works reliably
inside loops, which is something that CVP struggles with due to LVI
cycles.
I have made various optimizations to make PredicateInfo more efficient,
but unfortunately this still has significant compile-time cost (around
0.1-0.2%).
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