Re: [PATCH] haifa-sched: fix autopref_rank_for_schedule qsort comparator

[Alexander Monakov]

On Tue, 19 Sep 2017, Maxim Kuvyrkov wrote:
> How about the following:
> 1. if both instructions are "irrelevant", then return "0".
> 2. if one instruction is "relevant" and another is "irrelevant", then
> "relevant" instruction is always greater (or lesser) than the non-relevant. 
> 3. if both instructions are "relevant", then call autopref_rank_data.

Sounds good, the following patch implements this (with 'relevant' greater).

> I don't have immediate answer on whether "relevant" or "irrelevant"
> instructions should be pushed towards beginning of the ready list.  Possibly,
> we want to delay "relevant" instructions and push "irrelevant" towards
> beginning of ready list so that more "relevant" instructions can enter ready
> list as their dependencies are resolved from scheduling "irrelevant"
> instructions.
> 
> WDYT?

*nod*, this makes sense.

(bootstrap/regtest running on x86-64)

Thanks!

        * haifa-sched.c (autopref_rank_for_schedule): Order 'irrelevant' insns
        first, always call autopref_rank_data otherwise.

diff --git a/gcc/haifa-sched.c b/gcc/haifa-sched.c
index af0ed27b18f..8f006de2319 100644
--- a/gcc/haifa-sched.c
+++ b/gcc/haifa-sched.c
@@ -5707,7 +5707,8 @@ autopref_rank_data (autopref_multipass_data_t data1,
 static int
 autopref_rank_for_schedule (const rtx_insn *insn1, const rtx_insn *insn2)
 {
-  for (int write = 0; write < 2; ++write)
+  int r = 0;
+  for (int write = 0; write < 2 && !r; ++write)
     {
       autopref_multipass_data_t data1
        = &INSN_AUTOPREF_MULTIPASS_DATA (insn1)[write];
@@ -5716,21 +5717,20 @@ autopref_rank_for_schedule (const rtx_insn *insn1, 
const rtx_insn *insn2)
 
       if (data1->status == AUTOPREF_MULTIPASS_DATA_UNINITIALIZED)
        autopref_multipass_init (insn1, write);
-      if (data1->status == AUTOPREF_MULTIPASS_DATA_IRRELEVANT)
-       continue;
 
       if (data2->status == AUTOPREF_MULTIPASS_DATA_UNINITIALIZED)
        autopref_multipass_init (insn2, write);
-      if (data2->status == AUTOPREF_MULTIPASS_DATA_IRRELEVANT)
-       continue;
 
-      if (!rtx_equal_p (data1->base, data2->base))
-       continue;
+      int irrel1 = data1->status == AUTOPREF_MULTIPASS_DATA_IRRELEVANT;
+      int irrel2 = data2->status == AUTOPREF_MULTIPASS_DATA_IRRELEVANT;
 
-      return autopref_rank_data (data1, data2);
+      if (!irrel1 && !irrel2)
+       r = autopref_rank_data (data1, data2);
+      else
+       r = irrel2 - irrel1;
     }
 
-  return 0;
+  return r;
 }
 
 /* True if header of debug dump was printed.  */