From a054c1673af1bff900a0cb4123e34d64e986a76d Mon Sep 17 00:00:00 2001
From: Felix Weiglhofer <weiglhofer@fias.uni-frankfurt.de>
Date: Tue, 3 Oct 2023 16:40:49 +0200
Subject: [PATCH] algo: Add CBM_PARALLEL_FOR macro.
---
.clang-format | 1 +
algo/base/compat/OpenMP.h | 15 +++++++++++++++
algo/unpack/Unpack.cxx | 5 +++--
3 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/.clang-format b/.clang-format
index 7b2366f332..c6d26b29a7 100644
--- a/.clang-format
+++ b/.clang-format
@@ -147,6 +147,7 @@ SpacesInParentheses: false
SpacesInSquareBrackets: false
WhitespaceSensitiveMacros: ['CBM_ENUM_DICT']
+StatementMacros: ['CBM_PARALLEL_FOR']
Standard: c++11
diff --git a/algo/base/compat/OpenMP.h b/algo/base/compat/OpenMP.h
index 9129cdde38..16991f1bed 100644
--- a/algo/base/compat/OpenMP.h
+++ b/algo/base/compat/OpenMP.h
@@ -10,6 +10,21 @@
#include <omp.h>
#endif
+#define CBM_PRAGMA(...) _Pragma(#__VA_ARGS__)
+
+// OpenMP parallel for
+// If OpenMP is not available, this macro expands to nothing
+//
+// Hiding the pragma in a macro isn't technically necessary, as the compiler will ignore it if OpenMP is not available.
+// But it slightly increases readability as it's indented to the same level as the code it applies to.
+//
+// Accepts the same arguments as the OpenMP parallel for pragma.
+#ifdef HAVE_OMP
+#define CBM_PARALLEL_FOR(...) CBM_PRAGMA(omp parallel for __VA_ARGS__)
+#else
+#define CBM_PARALLEL_FOR(...)
+#endif
+
namespace cbm::algo::openmp
{
diff --git a/algo/unpack/Unpack.cxx b/algo/unpack/Unpack.cxx
index e5698e0c1f..9d001ade18 100644
--- a/algo/unpack/Unpack.cxx
+++ b/algo/unpack/Unpack.cxx
@@ -10,6 +10,7 @@
#include <xpu/host.h>
#include "compat/Algorithm.h"
+#include "compat/OpenMP.h"
#include "log.hpp"
using namespace std;
@@ -178,7 +179,7 @@ namespace cbm::algo
xpu::push_timer("Unpack");
xpu::t_add_bytes(sizeBytes);
-#pragma omp parallel for schedule(dynamic)
+ CBM_PARALLEL_FOR(schedule(dynamic))
for (size_t i = 0; i < numMs; i++) {
auto result = algos.at(msEqIds[i])(msContent[i], msDesc[i], ts.start_time());
msDigis[i] = std::move(result.first);
@@ -196,7 +197,7 @@ namespace cbm::algo
xpu::push_timer("Merge");
xpu::t_add_bytes(nDigisTotal * sizeof(Digi));
-#pragma omp parallel for schedule(dynamic)
+ CBM_PARALLEL_FOR(schedule(dynamic))
for (unsigned int i = 0; i < numMs; i++) {
unsigned int offset = 0;
for (unsigned int x = 0; x < i; x++)
--
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