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Differential D94358

[NFC][AMDGPU] Clarify memory model support for volatile
ClosedPublic

Authored by t-tye on Jan 9 2021, 2:25 AM.

Details

Reviewers
kzhuravl
b-sumner
rampitec
Commits
rG72f1f084670e: [NFC][AMDGPU] Clarify memory model support for volatile
Summary

Reorder the AMDGPUUage description of the memory model code sequences
for volatile so clear that it applies independent of the nontemporal
setting.

Diff Detail

Event Timeline

t-tye created this revision.Jan 9 2021, 2:25 AM
Herald added subscribers: kerbowa, tpr, dstuttard and 3 others. · View Herald TranscriptJan 9 2021, 2:25 AM
t-tye requested review of this revision.Jan 9 2021, 2:25 AM
Herald added a project: Restricted Project. · View Herald TranscriptJan 9 2021, 2:25 AM
Herald added subscribers: llvm-commits, wdng. · View Herald Transcript
Harbormaster completed remote builds in B84572: Diff 315584.Jan 9 2021, 3:05 AM
rampitec accepted this revision.Jan 11 2021, 10:11 AM
This revision is now accepted and ready to land.Jan 11 2021, 10:11 AM
Closed by commit rG72f1f084670e: [NFC][AMDGPU] Clarify memory model support for volatile (authored by t-tye). · Explain WhyJan 11 2021, 12:00 PM
This revision was automatically updated to reflect the committed changes.
t-tye added a commit: rG72f1f084670e: [NFC][AMDGPU] Clarify memory model support for volatile.

Revision Contents

PathSize
llvm/
docs/
48 lines

Diff 315897

llvm/docs/AMDGPUUsage.rst

  • This file is larger than 256 KB, so syntax highlighting is disabled by default.
Show First 20 Lines • Show All 4,726 Lines • ▼ Show 20 Lines LLVM Instr LLVM Memory LLVM Memory AMDGPU AMDGPU Machine Code
Space Space
============ ============ ============== ========== ================================ ============ ============ ============== ========== ================================
**Non-Atomic** **Non-Atomic**
------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------
load *none* *none* - global - !volatile & !nontemporal load *none* *none* - global - !volatile & !nontemporal
- generic - generic
- private 1. buffer/global/flat_load - private 1. buffer/global/flat_load
- constant - constant
- volatile & !nontemporal - !volatile & nontemporal
1. buffer/global/flat_load
glc=1 slc=1
- volatile
1. buffer/global/flat_load 1. buffer/global/flat_load
glc=1 glc=1
2. s_waitcnt vmcnt(0) 2. s_waitcnt vmcnt(0)
- Must happen before - Must happen before
any following volatile any following volatile
global/generic global/generic
load/store. load/store.
- Ensures that - Ensures that
volatile volatile
operations to operations to
different different
addresses will not addresses will not
be reordered by be reordered by
hardware. hardware.
- !volatile & nontemporal
1. buffer/global/flat_load
glc=1 slc=1
load *none* *none* - local 1. ds_load load *none* *none* - local 1. ds_load
store *none* *none* - global - !volatile & !nontemporal store *none* *none* - global - !volatile & !nontemporal
- generic - generic
- private 1. buffer/global/flat_store - private 1. buffer/global/flat_store
- constant - constant
- volatile & !nontemporal - !volatile & nontemporal
1. buffer/global/flat_store
glc=1 slc=1
- volatile
1. buffer/global/flat_store 1. buffer/global/flat_store
2. s_waitcnt vmcnt(0) 2. s_waitcnt vmcnt(0)
- Must happen before - Must happen before
any following volatile any following volatile
global/generic global/generic
load/store. load/store.
- Ensures that - Ensures that
volatile volatile
operations to operations to
different different
addresses will not addresses will not
be reordered by be reordered by
hardware. hardware.
- !volatile & nontemporal
1. buffer/global/flat_store
glc=1 slc=1
store *none* *none* - local 1. ds_store store *none* *none* - local 1. ds_store
**Unordered Atomic** **Unordered Atomic**
------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------
load atomic unordered *any* *any* *Same as non-atomic*. load atomic unordered *any* *any* *Same as non-atomic*.
store atomic unordered *any* *any* *Same as non-atomic*. store atomic unordered *any* *any* *Same as non-atomic*.
atomicrmw unordered *any* *any* *Same as monotonic atomic*. atomicrmw unordered *any* *any* *Same as monotonic atomic*.
**Monotonic Atomic** **Monotonic Atomic**
------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------
▲ Show 20 Lines • Show All 1,236 Lines • ▼ Show 20 Lines LLVM Instr LLVM Memory LLVM Memory AMDGPU AMDGPU Machine Code
Space Space
============ ============ ============== ========== ================================ ============ ============ ============== ========== ================================
**Non-Atomic** **Non-Atomic**
------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------
load *none* *none* - global - !volatile & !nontemporal load *none* *none* - global - !volatile & !nontemporal
- generic - generic
- private 1. buffer/global/flat_load - private 1. buffer/global/flat_load
- constant - constant
- volatile & !nontemporal - !volatile & nontemporal
1. buffer/global/flat_load
slc=1
- volatile
1. buffer/global/flat_load 1. buffer/global/flat_load
glc=1 dlc=1 glc=1 dlc=1
2. s_waitcnt vmcnt(0) 2. s_waitcnt vmcnt(0)
- Must happen before - Must happen before
any following volatile any following volatile
global/generic global/generic
load/store. load/store.
- Ensures that - Ensures that
volatile volatile
operations to operations to
different different
addresses will not addresses will not
be reordered by be reordered by
hardware. hardware.
- !volatile & nontemporal
1. buffer/global/flat_load
slc=1
load *none* *none* - local 1. ds_load load *none* *none* - local 1. ds_load
store *none* *none* - global - !volatile & !nontemporal store *none* *none* - global - !volatile & !nontemporal
- generic - generic
- private 1. buffer/global/flat_store - private 1. buffer/global/flat_store
- constant - constant
- volatile & !nontemporal - !volatile & nontemporal
1. buffer/global/flat_store
slc=1
- volatile
1. buffer/global/flat_store 1. buffer/global/flat_store
2. s_waitcnt vscnt(0) 2. s_waitcnt vscnt(0)
- Must happen before - Must happen before
any following volatile any following volatile
global/generic global/generic
load/store. load/store.
- Ensures that - Ensures that
volatile volatile
operations to operations to
different different
addresses will not addresses will not
be reordered by be reordered by
hardware. hardware.
- !volatile & nontemporal
1. buffer/global/flat_store
slc=1
store *none* *none* - local 1. ds_store store *none* *none* - local 1. ds_store
**Unordered Atomic** **Unordered Atomic**
------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------
load atomic unordered *any* *any* *Same as non-atomic*. load atomic unordered *any* *any* *Same as non-atomic*.
store atomic unordered *any* *any* *Same as non-atomic*. store atomic unordered *any* *any* *Same as non-atomic*.
atomicrmw unordered *any* *any* *Same as monotonic atomic*. atomicrmw unordered *any* *any* *Same as monotonic atomic*.
**Monotonic Atomic** **Monotonic Atomic**
------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------
▲ Show 20 Lines • Show All 3,405 Lines • Show Last 20 Lines