[all-commits] [llvm/llvm-project] 38f9c0: SystemZ: Stop casting fp typed atomic loads in the...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 38f9c013a090b666328aecceac03dda84d2b14ca
      https://github.com/llvm/llvm-project/commit/38f9c013a090b666328aecceac03dda84d2b14ca
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2024-05-02 (Thu, 02 May 2024)

  Changed paths:
    M llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
    M llvm/test/CodeGen/SystemZ/atomic-load-08.ll

  Log Message:
  -----------
  SystemZ: Stop casting fp typed atomic loads in the IR (#90768)

shouldCastAtomicLoadInIR is a hack that should be removed. Simple
bitcasting of operations should be in the domain of ordinary type
legalization and does not need to be done in the IR.

This introduces a code quality regression due to the hack currently used
to avoid using 128-bit values in the case where the floating point value
is ultimately used as an integer. This would be avoidable if there were
always a legal 128-bit type (like v2i64). This is a pretty niche
situation so I assume it's not important.

I implemented about 85% of the work necessary to make v2i64 legal, but
it was taking too long and I lack the necessary familiarity with systemz
to complete it. I've pushed it here for someone to pick up:
https://github.com/arsenm/llvm-project/pull/new/systemz-legal-v2i64

Depends #90861



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