From 86ed7d2b5b104e5e42b0ca949aa42e203a790cc0 Mon Sep 17 00:00:00 2001
From: Axel Huebl <axel.huebl@plasma.ninja>
Date: Fri, 7 Apr 2023 16:27:17 -0700
Subject: [PATCH] ParticleTileData: No Restrict in Storage (#3245)

## Summary

Remove the `restrict` qualifier from `GpuArray` members in
`ParticleTileData`. We see compilation problems with, among others Clang
14.0.6 and AppleClang, for this construct.

We expect that using `restrict` (`AMREX_RESTRICT`) on APIs as well as
aliased pointers in these arrays before access should be sufficient to
prevent that the compiler thinks that individual arrays alias each other
in hot loops.

## Additional background

- WarpX build regressions since 23.03, e.g.,
  - https://github.com/conda-forge/warpx-feedstock/pull/63
  - https://github.com/conda-forge/warpx-feedstock/pull/64
  - https://github.com/ECP-WarpX/WarpX/pull/3817
- independently, about to be remove in
https://github.com/AMReX-Codes/amrex/pull/2878
---
 Src/Particle/AMReX_ParticleTile.H | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Src/Particle/AMReX_ParticleTile.H b/Src/Particle/AMReX_ParticleTile.H
index 4374197d335..a0a762862d4 100644
--- a/Src/Particle/AMReX_ParticleTile.H
+++ b/Src/Particle/AMReX_ParticleTile.H
@@ -22,8 +22,8 @@ struct ParticleTileData
 
     Long m_size;
     ParticleType* AMREX_RESTRICT m_aos;
-    GpuArray<ParticleReal* AMREX_RESTRICT, NArrayReal> m_rdata;
-    GpuArray<int* AMREX_RESTRICT, NArrayInt> m_idata;
+    GpuArray<ParticleReal*, NArrayReal> m_rdata;
+    GpuArray<int*, NArrayInt> m_idata;
 
     int m_num_runtime_real;
     int m_num_runtime_int;
@@ -170,8 +170,8 @@ struct ConstParticleTileData
 
     Long m_size;
     const ParticleType* AMREX_RESTRICT m_aos;
-    GpuArray<const ParticleReal* AMREX_RESTRICT, NArrayReal> m_rdata;
-    GpuArray<const int* AMREX_RESTRICT, NArrayInt > m_idata;
+    GpuArray<const ParticleReal*, NArrayReal> m_rdata;
+    GpuArray<const int*, NArrayInt> m_idata;
 
     int m_num_runtime_real;
     int m_num_runtime_int;