llvm-project

b558ac0e - [InstCombine] Fix context for multi-use demanded bits simplification

[InstCombine] Fix context for multi-use demanded bits simplification When simplifying a multi-use root value, the demanded bits were reset to full, but we also need to reset the context extract. To make this convenient (without requiring by-value passing of SimplifyQuery), move the logic that that handles constants and dispatches to SimplifyDemandedUseBits/SimplifyMultipleUseDemandedBits into SimplifyDemandedBits. The SimplifyDemandedInstructionBits caller starts with full demanded bits and an appropriate context anyway. The different context instruction does mean that the ephemeral value protection no longer triggers in some cases, as the changes to assume tests show. An alternative, which I will explore in a followup, is to always use SimplifyMultipleUseDemandedBits() -- the previous root special case is only really intended for SimplifyDemandedInstructionBits(), which now no longer shares this code path. Fixes https://github.com/llvm/llvm-project/issues/97330.