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llvm-mirror/test/CodeGen/AMDGPU/limit-coalesce.mir
Stanislav Mekhanoshin 3a97f30b01 [AMDGPU] Do not allow register coalescer to create big superregs
Limit register coalescer by not allowing it to artificially increase
size of registers beyond dword. Such super-registers are in fact
register sequences and not distinct HW registers.

With more super-regs we would need to allocate adjacent registers
and constraint regalloc more than needed. Moreover, our super
registers are overlapping. For instance we have VGPR0_VGPR1_VGPR2,
VGPR1_VGPR2_VGPR3, VGPR2_VGPR3_VGPR4 etc, which complicates registers
allocation even more, resulting in excessive spilling.

Differential Revision: https://reviews.llvm.org/D28782

llvm-svn: 292413
2017-01-18 17:30:05 +00:00

72 lines
2.1 KiB
YAML

# RUN: llc -march=amdgcn -run-pass simple-register-coalescing -o - %s | FileCheck %s
# Check that coalescer does not create wider register tuple than in source
# CHECK: - { id: 2, class: vreg_64 }
# CHECK: - { id: 3, class: vreg_64 }
# CHECK: - { id: 4, class: vreg_64 }
# CHECK: - { id: 5, class: vreg_96 }
# CHECK: - { id: 6, class: vreg_96 }
# CHECK: - { id: 7, class: vreg_128 }
# CHECK: - { id: 8, class: vreg_128 }
# No more registers shall be defined
# CHECK-NEXT: liveins:
# CHECK: FLAT_STORE_DWORDX2 %vgpr0_vgpr1, %4,
# CHECK: FLAT_STORE_DWORDX3 %vgpr0_vgpr1, %6,
---
name: main
alignment: 0
exposesReturnsTwice: false
legalized: false
regBankSelected: false
selected: false
tracksRegLiveness: true
registers:
- { id: 1, class: sreg_32_xm0, preferred-register: '%1' }
- { id: 2, class: vreg_64, preferred-register: '%2' }
- { id: 3, class: vreg_64 }
- { id: 4, class: vreg_64 }
- { id: 5, class: vreg_64 }
- { id: 6, class: vreg_96 }
- { id: 7, class: vreg_96 }
- { id: 8, class: vreg_128 }
- { id: 9, class: vreg_128 }
liveins:
- { reg: '%sgpr6', virtual-reg: '%1' }
frameInfo:
isFrameAddressTaken: false
isReturnAddressTaken: false
hasStackMap: false
hasPatchPoint: false
stackSize: 0
offsetAdjustment: 0
maxAlignment: 0
adjustsStack: false
hasCalls: false
maxCallFrameSize: 0
hasOpaqueSPAdjustment: false
hasVAStart: false
hasMustTailInVarArgFunc: false
body: |
bb.0.entry:
liveins: %sgpr0, %vgpr0_vgpr1
%3 = IMPLICIT_DEF
undef %4.sub0 = COPY %sgpr0
%4.sub1 = COPY %3.sub0
undef %5.sub0 = COPY %4.sub1
%5.sub1 = COPY %4.sub0
FLAT_STORE_DWORDX2 %vgpr0_vgpr1, killed %5, 0, 0, 0, implicit %exec, implicit %flat_scr
%6 = IMPLICIT_DEF
undef %7.sub0_sub1 = COPY %6
%7.sub2 = COPY %3.sub0
FLAT_STORE_DWORDX3 %vgpr0_vgpr1, killed %7, 0, 0, 0, implicit %exec, implicit %flat_scr
%8 = IMPLICIT_DEF
undef %9.sub0_sub1_sub2 = COPY %8
%9.sub3 = COPY %3.sub0
FLAT_STORE_DWORDX4 %vgpr0_vgpr1, killed %9, 0, 0, 0, implicit %exec, implicit %flat_scr
...