[all-commits] [llvm/llvm-project] 578999: [AMDGPU] Make GCNRegBankReassign assign based on s...

[Carl Ritson via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 57899934eab18bbcab3482cc3ef862b0a1617ad0
      https://github.com/llvm/llvm-project/commit/57899934eab18bbcab3482cc3ef862b0a1617ad0
  Author: Carl Ritson <carl.ritson at amd.com>
  Date:   2020-08-04 (Tue, 04 Aug 2020)

  Changed paths:
    M llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/insertelement.ll
    A llvm/test/CodeGen/AMDGPU/regbank-reassign-wave64.mir
    M llvm/test/CodeGen/AMDGPU/regbank-reassign.mir

  Log Message:
  -----------
  [AMDGPU] Make GCNRegBankReassign assign based on subreg banks

When scavenging consider the sub-register of the source operand
to determine the bank of a candidate register (not just sub0).
Without this it is possible to introduce an infinite loop,
e.g. $sgpr15_sgpr16_sgpr17 can be assigned for a conflict between
$sgpr0 and SGPR_96:sub1.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D84910