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| author | Ben Gamari <bgamari.foss@gmail.com> | 2018-02-03 11:37:01 -0500 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-02-03 11:37:14 -0500 |
| commit | 217e4170bdce3df28a667803ce5e619553bfecdd (patch) | |
| tree | 1e548bae29aecc72ce257dc962025c1388a7a7b5 /configure.ac | |
| parent | fdf518c708dc5a34ae810c5d5f3a4db812d226f0 (diff) | |
| download | haskell-217e4170bdce3df28a667803ce5e619553bfecdd.tar.gz | |
ghc-prim: Emulate C11 atomics when not available
GCC's __sync primitives apparently "usually" imply a full barrier,
meaning they can be used to emulate the more precise C11 atomics albeit
with a loss of efficiency. This restores compatibility with GCC 4.4.
This partially reverts commit 59de290928e6903337f31c1f8107ac8a98ea145d.
Test Plan: Validate on Centos
Reviewers: hvr, simonmar, trommler
Subscribers: rwbarton, thomie, erikd, carter
GHC Trac Issues: #14244
Differential Revision: https://phabricator.haskell.org/D4364
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 216a97fb49..5bf096b3d0 100644 --- a/configure.ac +++ b/configure.ac @@ -712,6 +712,11 @@ FP_GCC_VERSION dnl ** See whether gcc supports -no-pie FP_GCC_SUPPORTS_NO_PIE +dnl ** Used to determine how to compile ghc-prim's atomics.c, used by +dnl unregisterised, Sparc, and PPC backends. +FP_GCC_SUPPORTS__ATOMICS +AC_DEFINE([HAVE_C11_ATOMICS], [$CONF_GCC_SUPPORTS__ATOMICS], [Does GCC support __atomic primitives?]) + FP_GCC_EXTRA_FLAGS dnl ** look to see if we have a C compiler using an llvm back end. |