re PR rtl-optimization/70478 ([LRA] S/390: Performance regression - superfluous stack...

2017-04-10  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/70478
	* lra-constraints.c (curr_small_class_check): New.
	(update_and_check_small_class_inputs): New.
	(process_alt_operands): Update curr_small_class_check.  Disfavor
	alternative insn memory operands.  Check available regs for small
	class operands.

From-SVN: r246808

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bf3119afa1de0b4e189d37f36c36faecba1f814f..00b994b5245d13756111b58f891ec18cd70f193a 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2017-04-10  Vladimir Makarov  <vmakarov@redhat.com>
+
+       PR rtl-optimization/70478
+       * lra-constraints.c (curr_small_class_check): New.
+       (update_and_check_small_class_inputs): New.
+       (process_alt_operands): Update curr_small_class_check.  Disfavor
+       alternative insn memory operands.  Check available regs for small
+       class operands.
+
 2017-03-31  Matthew Fortune  <matthew.fortune@imgtec.com>
 
        PR target/80057

diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index 4d986249a6fa6df1ad497d0830395dc3fed23f92..82b1ed0d403122dc58898d0e6ac678ff9ea4b725 100644 (file)
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -1852,6 +1852,42 @@ prohibited_class_reg_set_mode_p (enum reg_class rclass,
          (temp, ira_prohibited_class_mode_regs[rclass][mode]));
 }
 
+
+/* Used to check validity info about small class input operands.  It
+   should be incremented at start of processing an insn
+   alternative.  */
+static unsigned int curr_small_class_check = 0;
+
+/* Update number of used inputs of class OP_CLASS for operand NOP.
+   Return true if we have more such class operands than the number of
+   available regs.  */
+static bool
+update_and_check_small_class_inputs (int nop, enum reg_class op_class)
+{
+  static unsigned int small_class_check[LIM_REG_CLASSES];
+  static int small_class_input_nums[LIM_REG_CLASSES];
+  
+  if (SMALL_REGISTER_CLASS_P (op_class)
+      /* We are interesting in classes became small because of fixing
+        some hard regs, e.g. by an user through GCC options.  */
+      && hard_reg_set_intersect_p (reg_class_contents[op_class],
+                                  ira_no_alloc_regs)
+      && (curr_static_id->operand[nop].type != OP_OUT
+         || curr_static_id->operand[nop].early_clobber))
+    {
+      if (small_class_check[op_class] == curr_small_class_check)
+       small_class_input_nums[op_class]++;
+      else
+       {
+         small_class_check[op_class] = curr_small_class_check;
+         small_class_input_nums[op_class] = 1;
+       }
+      if (small_class_input_nums[op_class] > ira_class_hard_regs_num[op_class])
+       return true;
+    }
+  return false;
+}
+
 /* Major function to choose the current insn alternative and what
    operands should be reloaded and how.         If ONLY_ALTERNATIVE is not
    negative we should consider only this alternative.  Return false if
@@ -1952,6 +1988,7 @@ process_alt_operands (int only_alternative)
       if (!TEST_BIT (preferred, nalt))
        continue;
 
+      curr_small_class_check++;
       overall = losers = addr_losers = 0;
       static_reject = reject = reload_nregs = reload_sum = 0;
       for (nop = 0; nop < n_operands; nop++)
@@ -2685,6 +2722,21 @@ process_alt_operands (int only_alternative)
                    }
                }
 
+             /* When we use memory operand, the insn should read the
+                value from memory and even if we just wrote a value
+                into the memory it is costly in comparison with an
+                insn alternative which does not use memory
+                (e.g. register or immediate operand).  */
+             if (no_regs_p && offmemok)
+               {
+                 if (lra_dump_file != NULL)
+                   fprintf
+                     (lra_dump_file,
+                      "            Using memory insn operand %d: reject+=3\n",
+                      nop);
+                 reject += 3;
+               }
+             
 #ifdef SECONDARY_MEMORY_NEEDED
              /* If reload requires moving value through secondary
                 memory, it will need one more insn at least.  */
@@ -2747,6 +2799,14 @@ process_alt_operands (int only_alternative)
               goto fail;
             }
 
+         if (update_and_check_small_class_inputs (nop, this_alternative))
+           {
+             if (lra_dump_file != NULL)
+               fprintf (lra_dump_file,
+                        "            alt=%d, not enough small class regs -- refuse\n",
+                        nalt);
+             goto fail;
+           }
          curr_alt[nop] = this_alternative;
          COPY_HARD_REG_SET (curr_alt_set[nop], this_alternative_set);
          curr_alt_win[nop] = this_alternative_win;