Fix check whether GCC supports __atomic_ builtins
authorIlias Tsitsimpis <iliastsi@debian.org>
Tue, 18 Sep 2018 15:45:17 +0000 (17:45 +0200)
committerKrzysztof Gogolewski <krz.gogolewski@gmail.com>
Tue, 18 Sep 2018 17:05:56 +0000 (19:05 +0200)
Summary:
C11 atomics are never used because:

* The program used for checking whether GCC supports
__atomic_ builtins fails with the following error:

```
  error: size mismatch in argument 2 of `__atomic_load`
   int test(int *x) { int y; __atomic_load(&x, &y, __ATOMIC_SEQ_CST); return x; }
```

* There is a typo when checking if CONF_GCC_SUPPORTS__ATOMICS equals YES,
resulting in PRIM_CFLAGS and PRIM_EXTRA_LIBRARIES never being set.

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, erikd, carter

Differential Revision: https://phabricator.haskell.org/D5154

libraries/ghc-prim/aclocal.m4
libraries/ghc-prim/configure.ac

index e569538..81fc44c 100644 (file)
@@ -5,7 +5,7 @@ AC_DEFUN([FP_GCC_SUPPORTS__ATOMICS],
 [
    AC_REQUIRE([AC_PROG_CC])
    AC_MSG_CHECKING([whether GCC supports __atomic_ builtins])
-   echo 'int test(int *x) { int y; __atomic_load(&x, &y, __ATOMIC_SEQ_CST); return x; }' > conftest.c
+   echo 'int test(int *x) { int y; __atomic_load(x, &y, __ATOMIC_SEQ_CST); return y; }' > conftest.c
    if $CC -c conftest.c > /dev/null 2>&1; then
        CONF_GCC_SUPPORTS__ATOMICS=YES
        AC_MSG_RESULT([yes])
index bacc89c..8249be3 100644 (file)
@@ -8,7 +8,7 @@ dnl    unregisterised, Sparc, and PPC backends.
 FP_GCC_SUPPORTS__ATOMICS
 AC_DEFINE([HAVE_C11_ATOMICS], [$CONF_GCC_SUPPORTS__ATOMICS], [Does GCC support __atomic primitives?])
 
-if test "x$CONF_GCC_SUPPORTS__ATOMICS" = YES
+if test "$CONF_GCC_SUPPORTS__ATOMICS" = "YES"
 then PRIM_CFLAGS=-DHAVE_C11_ATOMICS
      PRIM_EXTRA_LIBRARIES=atomic
 fi