This allows to add facts even if no corresponding ICmp instruction
exists in the IR.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D158837
Handling `true` and `false` constant replacements is now abstracted
out into a single lambda function `ReplaceCmpWithConstant`, so as to
reduce code duplication.
This allows interleaving facts and checks in a single block. In
particular this enables using facts from assumes for conditions in the
same block that come after the assume.
This could be extended to only try to simplify checks at the point where
a condition is used.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D138452
