Scheduling should never move very expensive instructions to places they
are executed more frequently. This patch fixes that, reducing the
execution time of c-ray by over 40% (I tested on a BE Power7 system).
Is there some existing way to test for "very expensive insn" or "very
expensive insn we should not speculate"? Should there be a new hook?
Is only disallowing (FP) SQRT and DIV a good solution?
Segher
---
gcc/sched-rgn.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/gcc/sched-rgn.c b/gcc/sched-rgn.c
index 2af3a03..6ccd973 100644
--- a/gcc/sched-rgn.c
+++ b/gcc/sched-rgn.c
@@ -64,6 +64,7 @@ along with GCC; see the file COPYING3. If not see
#include "sel-sched.h"
#include "tree-pass.h"
#include "dbgcnt.h"
+#include "rtl-iter.h"
#include "pretty-print.h"
#include "print-rtl.h"
@@ -2147,12 +2148,20 @@ static int
can_schedule_ready_p (rtx_insn *insn)
{
/* An interblock motion? */
- if (INSN_BB (insn) != target_bb
- && IS_SPECULATIVE_INSN (insn)
- && !check_live (insn, INSN_BB (insn)))
- return 0;
- else
- return 1;
+ if (INSN_BB (insn) != target_bb && IS_SPECULATIVE_INSN (insn))
+ {
+ /* Cannot schedule this insn unless all operands are live. */
+ if (!check_live (insn, INSN_BB (insn)))
+ return 0;
+
+ /* Should not move expensive instructions speculatively. */
+ subrtx_iterator::array_type array;
+ FOR_EACH_SUBRTX (iter, array, insn, NONCONST)
+ if (*iter && GET_CODE (*iter) == SQRT)
+ return 0;
+ }
+
+ return 1;
}
/* Updates counter and other information. Split from can_schedule_ready_p ()
--
1.9.3
