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authorPaolo Bonzini <bonzini@gnu.org>2009-04-09 10:57:03 +0000
committerPaolo Bonzini <bonzini@gcc.gnu.org>2009-04-09 10:57:03 +0000
commit4a77c72b6b82fe31fa897ef5ced8579b706c9dfc (patch)
treeece9481c78c8bf125765823a7704da2edc3e28dd /gcc/doc
parentbf080c96e02d9b10dd18d7e900ed0c84d0d214af (diff)
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i386.md (cmpcc): New.
2009-04-09 Paolo Bonzini <bonzini@gnu.org> * config/i386/i386.md (cmpcc): New. * config/i386/sync.md (sync_compare_and_swap*): Set FLAGS_REG. (sync_compare_and_swap_cc*): Delete. * config/s390/s390.c (s390_compare_emitted): Remove. (s390_emit_compare): Handle MODE_CC s390_compare_op0 like s390_compare_emitted used to be handled. Assert that modes match. (s390_emit_compare_and_swap): Use s390_emit_compare, do not refer to sync_compare_and_swap_ccsi. * config/s390/s390.h (s390_compare_emitted): Remove. * config/s390/s390.md (seq): Look for MODE_CC s390_compare_op0 instead of s390_compare_emitted. (stack_protect_test, sync_compare_and_swap_cc): Set s390_compare_op0 instead of s390_compare_emitted. * config/s390/s390.md (cmpcc): New. (sync_compare_and_swapqi, sync_compare_and_swaphi): Clobber CC_REGNUM, do not pretend it's set. (sync_compare_and_swap_cc*): Delete. * config/s390/predicates.md (cc_reg_operand): New. * expr.c (sync_compare_and_swap_cc): Delete. * optabs.h (sync_compare_and_swap_cc): Delete. * optabs.c (prepare_cmp_insn): Ignore which specific CCmode is being used with can_compare_p. (emit_cmp_and_jump_insn_1): Likewise when looking in the optab. (find_cc_set): New. (expand_bool_compare_and_swap): Do not use sync_compare_and_swap_cc, look for a MODE_CC set instead. Use emit_store_flag. (expand_compare_and_swap_loop): Likewise, with some additional complication to avoid a force_reg when useless. Use emit_cmp_and_jump_insns. * genopinit.c (optabs): Delete sync_compare_and_swap_cc. * doc/md.texi (sync_compare_and_swap_cc): Merge with sync_compare_and_swap documentation. java: 2009-04-09 Paolo Bonzini <bonzini@gnu.org> * builtins.c (compareAndSwapLong_builtin, compareAndSwapInt_builtin, compareAndSwapObject_builtin, VMSupportsCS8_builtin): Do not look at sync_compare_and_swap_cc. From-SVN: r145825
Diffstat (limited to 'gcc/doc')
-rw-r--r--gcc/doc/md.texi22
1 files changed, 9 insertions, 13 deletions
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 25de8b1..a78233c 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -5091,19 +5091,15 @@ memory operations before the atomic operation occur before the atomic
operation and all memory operations after the atomic operation occur
after the atomic operation.
-@cindex @code{sync_compare_and_swap_cc@var{mode}} instruction pattern
-@item @samp{sync_compare_and_swap_cc@var{mode}}
-
-This pattern is just like @code{sync_compare_and_swap@var{mode}}, except
-it should act as if compare part of the compare-and-swap were issued via
-@code{cmp@var{m}}. This comparison will only be used with @code{EQ} and
-@code{NE} branches and @code{setcc} operations.
-
-Some targets do expose the success or failure of the compare-and-swap
-operation via the status flags. Ideally we wouldn't need a separate
-named pattern in order to take advantage of this, but the combine pass
-does not handle patterns with multiple sets, which is required by
-definition for @code{sync_compare_and_swap@var{mode}}.
+For targets where the success or failure of the compare-and-swap
+operation is available via the status flags, it is possible
+to avoid a separate compare operation and issue the subsequent
+setcc or branch immediately after the compare-and-swap. To this
+end, GCC will look for a @code{MODE_CC} set in the output of
+@code{sync_compare_and_swap@var{mode}}; if the machine description
+includes such a set, the target should also define a special @code{cmpcc}
+instruction. GCC will then be able to take the destination of the
+@code{MODE_CC} set and use it as the first operand of @code{cmpcc}.
@cindex @code{sync_add@var{mode}} instruction pattern
@cindex @code{sync_sub@var{mode}} instruction pattern