From: mwahab Date: Mon, 29 Jun 2015 16:09:10 +0000 (+0000) Subject: 2015-06-29 Matthew Wahab X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=43ec128c05f42e114924fcfa08e92153983f9873;p=thirdparty%2Fgcc.git 2015-06-29 Matthew Wahab PR target/65697 * config/armc/arm.c (arm_split_compare_and_swap): For ARMv8, replace an initial acquire barrier with final barrier. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@225133 138bc75d-0d04-0410-961f-82ee72b054a4 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 2a7ef9d10502..6ecc469a8141 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2015-06-29 Matthew Wahab + + PR target/65697 + * config/armc/arm.c (arm_split_compare_and_swap): For ARMv8, replace an + initial acquire barrier with final barrier. + 2015-06-29 Matthew Wahab PR target/65697 diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index 56677634ee01..c2dce95e611e 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -27614,6 +27614,8 @@ arm_split_compare_and_swap (rtx operands[]) scratch = operands[7]; mode = GET_MODE (mem); + bool is_armv8_sync = arm_arch8 && is_mm_sync (mod_s); + bool use_acquire = TARGET_HAVE_LDACQ && !(is_mm_relaxed (mod_s) || is_mm_consume (mod_s) || is_mm_release (mod_s)); @@ -27622,6 +27624,11 @@ arm_split_compare_and_swap (rtx operands[]) && !(is_mm_relaxed (mod_s) || is_mm_consume (mod_s) || is_mm_acquire (mod_s)); + /* For ARMv8, the load-acquire is too weak for __sync memory orders. Instead, + a full barrier is emitted after the store-release. */ + if (is_armv8_sync) + use_acquire = false; + /* Checks whether a barrier is needed and emits one accordingly. */ if (!(use_acquire || use_release)) arm_pre_atomic_barrier (mod_s); @@ -27662,7 +27669,8 @@ arm_split_compare_and_swap (rtx operands[]) emit_label (label2); /* Checks whether a barrier is needed and emits one accordingly. */ - if (!(use_acquire || use_release)) + if (is_armv8_sync + || !(use_acquire || use_release)) arm_post_atomic_barrier (mod_s); if (is_mm_relaxed (mod_f))