haifa-sched.c (ok_for_early_schedule): New function.

        * haifa-sched.c (ok_for_early_schedule): New function.
        (early_queue_to_ready): New function.
        (schedule_block): Allow early removal of insns from Q.
        (schedule_insn): Update INSN_TICK in case of premature
        issue.
        * common.opt (sched_stalled_insns): New flag.
        (sched_stalled_insns_dep): New flag.
        * flags.h: Same above flags.
        * opts.c: Same as above.
        * toplev.c: Same as above.
        * target.h (targetm.sched.is_costly_dependence): New
        hook.
        * target-def.h: Same as above.
        * config/rs6000/rs6000.h: (rs6000_sched_costly_dep):
        Support new flag -msched-costly-dep.
        (DEFAULT_SCHED_COSTLY_DEP): Define.
        * config/rs6000/rs6000.c:
        (rs6000_is_costly_dependence): New function.
        (is_load_insn, is_store_insn): New functions.
        (is_load_insn1, is_store_insn1, is_mem_ref): New
        functions.
        * doc/invoke.texi (-fsched-stalled-insns-dep)
        (-fsched-stalled-insns, -msched-costly-dep): Document
        options.
        * doc/tm.texi (is_costly_dependence): Define new
        scheduler target hook.

From-SVN: r72261

2 files changed, 49 insertions, 1 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index b943146..20ef67f 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -287,7 +287,9 @@ in the following sections.
 -frerun-cse-after-loop  -frerun-loop-opt @gol
 -frounding-math -fschedule-insns  -fschedule-insns2 @gol
 -fno-sched-interblock  -fno-sched-spec  -fsched-spec-load @gol
--fsched-spec-load-dangerous  -fsched2-use-superblocks @gol
+-fsched-spec-load-dangerous  @gol
+-fsched-stalled-insns=@var{n} -sched-stalled-insns-dep=@var{n} @gol
+-fsched2-use-superblocks @gol
 -fsched2-use-traces  -fsignaling-nans @gol
 -fsingle-precision-constant  -fssa  -fssa-ccp  -fssa-dce @gol
 -fstrength-reduce  -fstrict-aliasing  -ftracer  -fthread-jumps @gol
@@ -432,6 +434,7 @@ in the following sections.
 -mtoc  -mno-toc  -mlittle  -mlittle-endian  -mbig  -mbig-endian @gol
 -mdynamic-no-pic @gol
 -mprioritize-restricted-insns=@var{priority} @gol
+-msched-costly-dep=@var{dependence_type} @gol
 -mcall-sysv  -mcall-netbsd @gol
 -maix-struct-return  -msvr4-struct-return @gol
 -mabi=altivec  -mabi=no-altivec @gol
@@ -4115,6 +4118,18 @@ Allow speculative motion of more load instructions.  This only makes
 sense when scheduling before register allocation, i.e.@: with
 @option{-fschedule-insns} or at @option{-O2} or higher.
 
+@item -fsched-stalled-insns=@var{n}
+@opindex fsched-stalled-insns
+Define how many insns (if any) can be moved prematurely from the queue
+of stalled insns into the ready list, during the second scheduling pass.
+
+@item -fsched-stalled-insns-dep=@var{n}
+@opindex fsched-stalled-insns-dep
+Define how many insn groups (cycles) will be examined for a dependency 
+on a stalled insn that is candidate for premature removal from the queue 
+of stalled insns.  Has an effect only during the second scheduling pass, 
+and only if @option{-fsched-stalled-insns} is used and its value is not zero.
+
 @item -fsched2-use-superblocks
 @opindex fsched2-use-superblocks
 When scheduling after register allocation, do use superblock scheduling
@@ -7535,6 +7550,17 @@ pass.  The argument @var{priority} takes the value @var{0/1/2} to assign
 @var{no/highest/second-highest} priority to dispatch slot restricted 
 instructions.
 
+@item -msched-costly-dep=@var{dependence_type}
+@opindex msched-costly-dep
+This option controls which dependences are considered costly
+by the target during instruction scheduling.  The argument
+@var{dependence_type} takes one of the following values:
+@var{no}: no dependence is costly, 
+@var{all}: all dependences are costly, 
+@var{true_store_to_load}: a true dependence from store to load is costly,
+@var{store_to_load}: any dependence from store to load is costly,
+@var{number}: any dependence which latency >= @var{number} is costly.
+ 
 @item -mcall-sysv
 @opindex mcall-sysv
 On System V.4 and embedded PowerPC systems compile code using calling
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 2fa6fbd..1645319 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -5668,6 +5668,28 @@ zero.  The hook should return @code{NULL} if there are no more nop
 insns with indexes greater than given index.
 @end deftypefn
 
+@deftypefn {Target Hook} bool IS_COSTLY_DEPENDENCE (rtx @var{insn1}, rtx @var{insn2}, rtx @var{dep_link}, int @var{dep_cost}, int @var{distance})
+This hook is used to define which dependences are considered costly by
+the target, so costly that it is not advisable to schedule the insns that 
+are involved in the dependence too close to one another.  The parameters
+to this hook are as follows:  The second parameter @var{insn2} is dependent 
+upon the first parameter @var{insn1}.  The dependence between @var{insn1} 
+and @var{insn2} is represented by the third parameter @var{dep_link}.  The 
+fourth parameter @var{cost} is the cost of the dependence, and the fifth 
+parameter @var{distance} is the distance in cycles between the two insns. 
+The hook returns @code{true} if considering the distance between the two
+insns the dependence between them is considered costly by the target,
+and @code{false} otherwise.
+
+Defining this hook can be useful in multiple-issue out-of-order machines,
+where (a) it's practically hopeless to predict the actual data/resource 
+delays, however: (b) there's a better chance to predict the actual grouping
+that will be formed, and (c) correctly emulating the grouping can be very 
+important.  In such targets one may want to allow issuing dependent insns
+closer to one another - i.e, closer than the dependence distance;  however, 
+not in cases of "costly dependences", which this hooks allows to define.
+@end deftypefn
+
 Macros in the following table are generated by the program
 @file{genattr} and can be useful for writing the hooks.