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| author | Jeffrey A Law <law@cygnus.com> | 1998-06-05 11:32:28 +0000 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 1998-06-05 05:32:28 -0600 |
| commit | 2db4599393fa0727729a9106fd14582188539331 (patch) | |
| tree | 8b7b568cba192b365198f55d2e5552643d76ee81 /gcc | |
| parent | 192231fbe54b828f716f9ec44ed298dc61d6601c (diff) | |
| download | gcc-2db4599393fa0727729a9106fd14582188539331.zip gcc-2db4599393fa0727729a9106fd14582188539331.tar.gz gcc-2db4599393fa0727729a9106fd14582188539331.tar.bz2 | |
haifa-sched.c (rank_for_schedule): For "equally good insns", prefer the insn which has the most insns dependent on it.
* haifa-sched.c (rank_for_schedule): For "equally good insns", prefer
the insn which has the most insns dependent on it.
From-SVN: r20243
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/haifa-sched.c | 20 |
2 files changed, 23 insertions, 2 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index cf20fa3..c148593 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +Fri Jun 5 12:29:28 1998 Jeffrey A Law (law@cygnus.com) + + * haifa-sched.c (rank_for_schedule): For "equally good insns", prefer + the insn which has the most insns dependent on it. + Fri Jun 5 09:03:22 1998 John Carr <jfc@mit.edu> * alias.c (find_base_value): Avoid reading past end of reg_base_value. diff --git a/gcc/haifa-sched.c b/gcc/haifa-sched.c index 1c5245c..fed2a12 100644 --- a/gcc/haifa-sched.c +++ b/gcc/haifa-sched.c @@ -87,7 +87,8 @@ broken by 6. choose insn with the least dependences upon the previously scheduled insn, or finally - 7. choose insn with lowest UID. + 7 choose the insn which has the most insns dependent on it. + 8. choose insn with lowest UID. Memory references complicate matters. Only if we can be certain that memory references are not part of the data dependency graph @@ -4029,7 +4030,7 @@ rank_for_schedule (x, y) rtx tmp = *(rtx *)y; rtx tmp2 = *(rtx *)x; rtx link; - int tmp_class, tmp2_class; + int tmp_class, tmp2_class, depend_count1, depend_count2; int val, priority_val, spec_val, prob_val, weight_val; @@ -4090,6 +4091,21 @@ rank_for_schedule (x, y) return val; } + /* Prefer the insn which has more later insns that depend on it. + This gives the scheduler more freedom when scheduling later + instructions at the expense of added register pressure. */ + depend_count1 = 0; + for (link = INSN_DEPEND (tmp); link; link = XEXP (link, 1)) + depend_count1++; + + depend_count2 = 0; + for (link = INSN_DEPEND (tmp2); link; link = XEXP (link, 1)) + depend_count2++; + + val = depend_count2 - depend_count1; + if (val) + return val; + /* If insns are equally good, sort by INSN_LUID (original insn order), so that we make the sort stable. This minimizes instruction movement, thus minimizing sched's effect on debugging and cross-jumping. */ |