Every IR value kept two lists of its users: uses (the users) and
operandUses (the users with their operand index). AddArgument,
ReplaceArgument and ReplaceAllUsesWith updated both, and each value
allocated and freed both. Only operandUses is kept now. Uses() is a view
of the users in operandUses, and HasUses, UseCount and Invalidate read
it. sizeof(IrValue) drops from 152 to 128 bytes; the plan value encoder
writes no use lists, so only its size check changes.
The two lists held the same users in the same order, except after
ReplaceArgument on a user that took the value in more than one
operand: uses dropped the user's first entry and operandUses the
replaced operand's entry. Uses() now follows operandUses there too.
shader_ir_use_rewrite counted the allocations of both lists: its
allocation failure check now fails the one reserve ReplaceAllUsesWith
makes, and its growth check allows the allocations of one list, which
main exceeds.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
