[PATCH] D139673: [AMDGPU][SIFrameLowering] Mark VGPR used for AGPR spills as reserved

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added a comment.

In D139673#3982757 <https://reviews.llvm.org/D139673#3982757>, @arsenm wrote:

> We should work towards eliminating the special case handling of "spilling" between AGPRs and VGPRs. The allocator now knows they have a common allocatable class and introduces new vregs and copies as needed. We only still have this special handling because it breaks an optimization that works by accident now (which is unused subregister related)

The special handling is not about unused subregs. It is to allow not to spill the whole wide register into memory if there are free registers.


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