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llvm-project/llvm/test/CodeGen/AMDGPU/waitcnt-no-redundant.mir

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[AMDGPU] Suppress redundant waitcnt instrs. 1. Run the memory legalizer prior to the waitcnt pass; keep the policy that the waitcnt pass does not remove any waitcnts within the incoming IR. 2. The waitcnt pass doesn't (yet) track waitcnts that exist prior to the waitcnt pass (it just skips over them); because the waitcnt pass is ignorant of them, it may insert a redundant waitcnt. To avoid this, check the prev instr. If it and the to-be-inserted waitcnt are the same, suppress the insertion. We keep the existing waitcnt under the assumption that whomever, e.g., the memory legalizer, inserted it knows what they were doing. 3. Follow-on work: teach the waitcnt pass to record the pre-existing waitcnts for better waitcnt production. Differential Revision: https://reviews.llvm.org/D42854 llvm-svn: 324440
2018-02-07 10:21:21 +08:00
# RUN: llc -mtriple=amdgcn -verify-machineinstrs -run-pass si-insert-waitcnts -o - %s | FileCheck %s
# Check that the waitcnt pass does *not* insert a redundant waitcnt instr.
[AMDGPU] Make note of existing waitcnt instrs; this is add-on work related to suppression of redundant waitcnt instrs. It is necessary to make note of these existing waitcnt instrs so that we do not fall into an infinite loop when handling loops. Also, [NFC] some minor code clean-up. llvm-svn: 325524
2018-02-20 03:19:59 +08:00
# In this testcase, ensure that pass does not insert redundant S_WAITCNT 3952
[AMDGPU] Suppress redundant waitcnt instrs. 1. Run the memory legalizer prior to the waitcnt pass; keep the policy that the waitcnt pass does not remove any waitcnts within the incoming IR. 2. The waitcnt pass doesn't (yet) track waitcnts that exist prior to the waitcnt pass (it just skips over them); because the waitcnt pass is ignorant of them, it may insert a redundant waitcnt. To avoid this, check the prev instr. If it and the to-be-inserted waitcnt are the same, suppress the insertion. We keep the existing waitcnt under the assumption that whomever, e.g., the memory legalizer, inserted it knows what they were doing. 3. Follow-on work: teach the waitcnt pass to record the pre-existing waitcnts for better waitcnt production. Differential Revision: https://reviews.llvm.org/D42854 llvm-svn: 324440
2018-02-07 10:21:21 +08:00
...
# CHECK-LABEL: name: waitcnt-no-redundant
[AMDGPU] Make note of existing waitcnt instrs; this is add-on work related to suppression of redundant waitcnt instrs. It is necessary to make note of these existing waitcnt instrs so that we do not fall into an infinite loop when handling loops. Also, [NFC] some minor code clean-up. llvm-svn: 325524
2018-02-20 03:19:59 +08:00
# CHECK: S_WAITCNT 3952
[AMDGPU] Suppress redundant waitcnt instrs. 1. Run the memory legalizer prior to the waitcnt pass; keep the policy that the waitcnt pass does not remove any waitcnts within the incoming IR. 2. The waitcnt pass doesn't (yet) track waitcnts that exist prior to the waitcnt pass (it just skips over them); because the waitcnt pass is ignorant of them, it may insert a redundant waitcnt. To avoid this, check the prev instr. If it and the to-be-inserted waitcnt are the same, suppress the insertion. We keep the existing waitcnt under the assumption that whomever, e.g., the memory legalizer, inserted it knows what they were doing. 3. Follow-on work: teach the waitcnt pass to record the pre-existing waitcnts for better waitcnt production. Differential Revision: https://reviews.llvm.org/D42854 llvm-svn: 324440
2018-02-07 10:21:21 +08:00
# CHECK-NEXT: FLAT_ATOMIC_CMPSWAP
# CHECK-NEXT: S_WAITCNT 3952
[AMDGPU] Make note of existing waitcnt instrs; this is add-on work related to suppression of redundant waitcnt instrs. It is necessary to make note of these existing waitcnt instrs so that we do not fall into an infinite loop when handling loops. Also, [NFC] some minor code clean-up. llvm-svn: 325524
2018-02-20 03:19:59 +08:00
# CHECK-NEXT: BUFFER_WBINVL1
[AMDGPU] Suppress redundant waitcnt instrs. 1. Run the memory legalizer prior to the waitcnt pass; keep the policy that the waitcnt pass does not remove any waitcnts within the incoming IR. 2. The waitcnt pass doesn't (yet) track waitcnts that exist prior to the waitcnt pass (it just skips over them); because the waitcnt pass is ignorant of them, it may insert a redundant waitcnt. To avoid this, check the prev instr. If it and the to-be-inserted waitcnt are the same, suppress the insertion. We keep the existing waitcnt under the assumption that whomever, e.g., the memory legalizer, inserted it knows what they were doing. 3. Follow-on work: teach the waitcnt pass to record the pre-existing waitcnts for better waitcnt production. Differential Revision: https://reviews.llvm.org/D42854 llvm-svn: 324440
2018-02-07 10:21:21 +08:00
name: waitcnt-no-redundant
body: |
[AMDGPU] Make note of existing waitcnt instrs; this is add-on work related to suppression of redundant waitcnt instrs. It is necessary to make note of these existing waitcnt instrs so that we do not fall into an infinite loop when handling loops. Also, [NFC] some minor code clean-up. llvm-svn: 325524
2018-02-20 03:19:59 +08:00
bb.0:
renamable $vgpr0 = V_MOV_B32_e32 0, implicit $exec
bb.1:
S_WAITCNT 3952
FLAT_ATOMIC_CMPSWAP undef renamable $vgpr0_vgpr1, renamable $vgpr0_vgpr1, 0, 0, implicit $exec, implicit $flat_scr
[AMDGPU] Suppress redundant waitcnt instrs. 1. Run the memory legalizer prior to the waitcnt pass; keep the policy that the waitcnt pass does not remove any waitcnts within the incoming IR. 2. The waitcnt pass doesn't (yet) track waitcnts that exist prior to the waitcnt pass (it just skips over them); because the waitcnt pass is ignorant of them, it may insert a redundant waitcnt. To avoid this, check the prev instr. If it and the to-be-inserted waitcnt are the same, suppress the insertion. We keep the existing waitcnt under the assumption that whomever, e.g., the memory legalizer, inserted it knows what they were doing. 3. Follow-on work: teach the waitcnt pass to record the pre-existing waitcnts for better waitcnt production. Differential Revision: https://reviews.llvm.org/D42854 llvm-svn: 324440
2018-02-07 10:21:21 +08:00
S_WAITCNT 3952
[AMDGPU] Make note of existing waitcnt instrs; this is add-on work related to suppression of redundant waitcnt instrs. It is necessary to make note of these existing waitcnt instrs so that we do not fall into an infinite loop when handling loops. Also, [NFC] some minor code clean-up. llvm-svn: 325524
2018-02-20 03:19:59 +08:00
BUFFER_WBINVL1 implicit $exec
S_BRANCH %bb.1
[AMDGPU] Suppress redundant waitcnt instrs. 1. Run the memory legalizer prior to the waitcnt pass; keep the policy that the waitcnt pass does not remove any waitcnts within the incoming IR. 2. The waitcnt pass doesn't (yet) track waitcnts that exist prior to the waitcnt pass (it just skips over them); because the waitcnt pass is ignorant of them, it may insert a redundant waitcnt. To avoid this, check the prev instr. If it and the to-be-inserted waitcnt are the same, suppress the insertion. We keep the existing waitcnt under the assumption that whomever, e.g., the memory legalizer, inserted it knows what they were doing. 3. Follow-on work: teach the waitcnt pass to record the pre-existing waitcnts for better waitcnt production. Differential Revision: https://reviews.llvm.org/D42854 llvm-svn: 324440
2018-02-07 10:21:21 +08:00
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