Hi Ahmed,
Am 2017-12-07 19:57, schrieb Ahmed Bougacha:
Hi Jonas,
On Tue, Oct 17, 2017 at 6:37 AM, Jonas Hahnfeld via cfe-commits
<cfe-commits@lists.llvm.org> wrote:
Author: hahnfeld
Date: Tue Oct 17 06:37:36 2017
New Revision: 315996
URL: http://llvm.org/viewvc/llvm-project?rev=315996&view=rev
Log:
[CMake][OpenMP] Customize default offloading arch
For the shuffle instructions in reductions we need at least sm_30
but the user may want to customize the default architecture.
Differential Revision: https://reviews.llvm.org/D38883
Modified:
cfe/trunk/CMakeLists.txt
cfe/trunk/include/clang/Config/config.h.cmake
cfe/trunk/lib/Driver/ToolChains/Cuda.cpp
cfe/trunk/lib/Driver/ToolChains/Cuda.h
Modified: cfe/trunk/CMakeLists.txt
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/CMakeLists.txt?rev=315996&r1=315995&r2=315996&view=diff
==============================================================================
--- cfe/trunk/CMakeLists.txt (original)
+++ cfe/trunk/CMakeLists.txt Tue Oct 17 06:37:36 2017
@@ -235,6 +235,17 @@ endif()
set(CLANG_DEFAULT_OPENMP_RUNTIME "libomp" CACHE STRING
"Default OpenMP runtime used by -fopenmp.")
+# OpenMP offloading requires at least sm_30 because we use shuffle
instructions
+# to generate efficient code for reductions.
+set(CLANG_OPENMP_NVPTX_DEFAULT_ARCH "sm_30" CACHE STRING
+ "Default architecture for OpenMP offloading to Nvidia GPUs.")
+string(REGEX MATCH "^sm_([0-9]+)$" MATCHED_ARCH
"${CLANG_OPENMP_NVPTX_DEFAULT_ARCH}")
+if (NOT DEFINED MATCHED_ARCH OR "${CMAKE_MATCH_1}" LESS 30)
+ message(WARNING "Resetting default architecture for OpenMP
offloading to Nvidia GPUs to sm_30")
This warning is pretty noisy and doesn't affect most people: I don't
know what it means but I get it in every cmake run.
Can we somehow restrict or disable it?
So the next line used to say
+ set(CLANG_OPENMP_NVPTX_DEFAULT_ARCH "sm_30" CACHE STRING
+ "Default architecture for OpenMP offloading to Nvidia GPUs."
FORCE)
which should make sure that the cache is updated to a "correct" value
and you only see the warning once. That said, we have raised the default
to "sm_35" today, maybe something has gone wrong here. Let me check that
and come back to you!
Cheers,
Jonas
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