+2016-03-03 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
+
+ PR rtl-optimization/69904
+ * config/arm/arm.c (arm_cannot_copy_insn_p):
+ Return true for load-exclusive instructions.
+
2016-03-03 Jakub Jelinek <jakub@redhat.com>
PR target/70021
}
}
-/* Must not copy any rtx that uses a pc-relative address. */
+/* Must not copy any rtx that uses a pc-relative address.
+ Also, disallow copying of load-exclusive instructions that
+ may appear after splitting of compare-and-swap-style operations
+ so as to prevent those loops from being transformed away from their
+ canonical forms (see PR 69904). */
static bool
arm_cannot_copy_insn_p (rtx_insn *insn)
|| XINT (x, 1) == UNSPEC_PIC_UNIFIED))
return true;
}
+
+ rtx set = single_set (insn);
+ if (set)
+ {
+ rtx src = SET_SRC (set);
+ if (GET_CODE (src) == ZERO_EXTEND)
+ src = XEXP (src, 0);
+
+ /* Catch the load-exclusive and load-acquire operations. */
+ if (GET_CODE (src) == UNSPEC_VOLATILE
+ && (XINT (src, 1) == VUNSPEC_LL
+ || XINT (src, 1) == VUNSPEC_LAX))
+ return true;
+ }
return false;
}
+2016-03-03 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
+
+ PR rtl-optimization/69904
+ * gcc.target/arm/pr69904.c: New test.
+
2016-03-03 Jakub Jelinek <jakub@redhat.com>
PR target/70021
--- /dev/null
+/* { dg-do compile } */
+/* { dg-options "-O2 -marm" } */
+/* { dg-require-effective-target arm_arch_v7a_ok } */
+/* { dg-add-options arm_arch_v7a } */
+
+/* Make sure that RTL optimizers don't do any unexpected transformations
+ on the compare_exchange loop. */
+
+#include <stdatomic.h>
+
+atomic_uint foo;
+atomic_uint bar;
+int glob;
+
+int
+main (void)
+{
+ glob = atomic_compare_exchange_strong (&foo, &bar, 0);
+ return glob;
+}
+
+/* { dg-final { scan-assembler-times "dmb\tish" 2 } } */
+/* { dg-final { scan-assembler-times "ldrex\t" 1 } } */
+/* { dg-final { scan-assembler-times "strex\t" 1 } } */