xtensa: optimize trampolines relaxation

Currently every fixup in the current segment is checked when relaxing
trampoline frag. This is very expensive. Make a searchable array of
fixups pointing at potentially oversized jumps at the beginning of every
relaxation pass and only check subset of this cache in the reach of
single jump from the trampoline frag currently being relaxed.

Original profile:

% time    self  children    called     name
-----------------------------------------
        370.16  593.38 12283048/12283048     relax_segment
  98.4  370.16  593.38 12283048         xtensa_relax_frag
         58.91  269.26 2691463834/2699602236     xtensa_insnbuf_from_chars
         68.35   68.17 811266668/813338977     S_GET_VALUE
         36.85   29.51 2684369246/2685538060     xtensa_opcode_decode
         28.34    8.84 2684369246/2685538060     xtensa_format_get_slot
         12.39    5.94 2691463834/2699775044     xtensa_format_decode
          0.03    4.60 4101109/4101109     relax_frag_for_align
          0.18    1.76  994617/994617      relax_frag_immed
          0.07    0.09 24556277/24851220     new_logical_line
          0.06    0.00 12283048/14067410     as_where
          0.04    0.00 7094588/15460506     xtensa_format_num_slots
          0.00    0.00       1/712477      xtensa_insnbuf_alloc
-----------------------------------------

Same data, after optimization:

% time    self  children    called     name
-----------------------------------------
          0.51    7.47 12283048/12283048     relax_segment
  58.0    0.51    7.47 12283048         xtensa_relax_frag
          0.02    4.08 4101109/4101109     relax_frag_for_align
          0.18    1.39  994617/994617      relax_frag_immed
          0.01    0.98     555/555         xtensa_cache_relaxable_fixups
          0.21    0.25 7094588/16693271     xtensa_insnbuf_from_chars
          0.06    0.12 24556277/24851220     new_logical_line
          0.06    0.00 7094588/15460506     xtensa_format_num_slots
          0.02    0.04 7094588/16866079     xtensa_format_decode
          0.05    0.00 12283048/14067410     as_where
          0.00    0.00       1/712477      xtensa_insnbuf_alloc
          0.00    0.00   93808/93808       xtensa_find_first_cached_fixup
-----------------------------------------

2015-05-02  Max Filippov  <jcmvbkbc@gmail.com>
gas/
	* config/tc-xtensa.c (cached_fixupS, fixup_cacheS): New typedefs.
	(struct cached_fixup, struct fixup_cache): New structures.
	(fixup_order, xtensa_make_cached_fixup),
	(xtensa_realloc_fixup_cache, xtensa_cache_relaxable_fixups),
	(xtensa_find_first_cached_fixup, xtensa_delete_cached_fixup),
	(xtensa_add_cached_fixup): New functions.
	(xtensa_relax_frag): Cache fixups pointing at potentially
	oversized jumps at the beginning of every relaxation pass. Only
	check subset of this cache in the reach of single jump from the
	trampoline frag currently being relaxed.

2 files changed, 207 insertions, 27 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 986f009..13b6705 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,16 @@
+2015-05-02  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* config/tc-xtensa.c (cached_fixupS, fixup_cacheS): New typedefs.
+	(struct cached_fixup, struct fixup_cache): New structures.
+	(fixup_order, xtensa_make_cached_fixup),
+	(xtensa_realloc_fixup_cache, xtensa_cache_relaxable_fixups),
+	(xtensa_find_first_cached_fixup, xtensa_delete_cached_fixup),
+	(xtensa_add_cached_fixup): New functions.
+	(xtensa_relax_frag): Cache fixups pointing at potentially
+	oversized jumps at the beginning of every relaxation pass. Only
+	check subset of this cache in the reach of single jump from the
+	trampoline frag currently being relaxed.
+
 2015-05-01  Nick Clifton  <nickc@redhat.com>
 
 	* config/rl78-parse.y (MULU): Remove ISA_G14.
diff --git a/gas/config/tc-xtensa.c b/gas/config/tc-xtensa.c
index 3e85b69..b1827fa 100644
--- a/gas/config/tc-xtensa.c
+++ b/gas/config/tc-xtensa.c
@@ -8785,6 +8785,154 @@ static long relax_frag_for_align (fragS *, long);
 static long relax_frag_immed
   (segT, fragS *, long, int, xtensa_format, int, int *, bfd_boolean);
 
+typedef struct cached_fixup cached_fixupS;
+struct cached_fixup
+{
+  int addr;
+  int target;
+  int delta;
+  fixS *fixP;
+};
+
+typedef struct fixup_cache fixup_cacheS;
+struct fixup_cache
+{
+  cached_fixupS *fixups;
+  unsigned n_fixups;
+  unsigned n_max;
+
+  segT seg;
+  fragS *first_frag;
+};
+
+static int fixup_order (const void *a, const void *b)
+{
+  const cached_fixupS *pa = a;
+  const cached_fixupS *pb = b;
+
+  if (pa->addr == pb->addr)
+    {
+      if (pa->target == pb->target)
+	{
+	  if (pa->fixP->fx_r_type == pb->fixP->fx_r_type)
+	    return 0;
+	  return pa->fixP->fx_r_type < pb->fixP->fx_r_type ?  -1 : 1;
+	}
+      return pa->target - pb->target;
+    }
+  return pa->addr - pb->addr;
+}
+
+static bfd_boolean xtensa_make_cached_fixup (cached_fixupS *o, fixS *fixP)
+{
+  xtensa_isa isa = xtensa_default_isa;
+  int addr = fixP->fx_frag->fr_address;
+  int target;
+  int delta;
+  symbolS *s = fixP->fx_addsy;
+  int slot;
+  xtensa_format fmt;
+  xtensa_opcode opcode;
+
+  if (fixP->fx_r_type < BFD_RELOC_XTENSA_SLOT0_OP ||
+      fixP->fx_r_type > BFD_RELOC_XTENSA_SLOT14_OP)
+    return FALSE;
+  target = S_GET_VALUE (s);
+  delta = target - addr;
+
+  if (abs(delta) < J_RANGE / 2)
+    return FALSE;
+
+  xtensa_insnbuf_from_chars (isa, trampoline_buf,
+			     (unsigned char *) fixP->fx_frag->fr_literal +
+			     fixP->fx_where, 0);
+  fmt = xtensa_format_decode (isa, trampoline_buf);
+  gas_assert (fmt != XTENSA_UNDEFINED);
+  slot = fixP->tc_fix_data.slot;
+  xtensa_format_get_slot (isa, fmt, slot, trampoline_buf, trampoline_slotbuf);
+  opcode = xtensa_opcode_decode (isa, fmt, slot, trampoline_slotbuf);
+  if (opcode != xtensa_j_opcode)
+    return FALSE;
+
+  o->addr = addr;
+  o->target = target;
+  o->delta = delta;
+  o->fixP = fixP;
+
+  return TRUE;
+}
+
+static void xtensa_realloc_fixup_cache (fixup_cacheS *cache, unsigned add)
+{
+  if (cache->n_fixups + add > cache->n_max)
+    {
+      cache->n_max = (cache->n_fixups + add) * 2;
+      cache->fixups = xrealloc (cache->fixups,
+				sizeof (*cache->fixups) * cache->n_max);
+    }
+}
+
+static void xtensa_cache_relaxable_fixups (fixup_cacheS *cache,
+					   segment_info_type *seginfo)
+{
+  fixS *fixP;
+
+  cache->n_fixups = 0;
+
+  for (fixP = seginfo->fix_root; fixP ; fixP = fixP->fx_next)
+    {
+      xtensa_realloc_fixup_cache (cache, 1);
+
+      if (xtensa_make_cached_fixup (cache->fixups + cache->n_fixups, fixP))
+	++cache->n_fixups;
+    }
+  qsort (cache->fixups, cache->n_fixups, sizeof (*cache->fixups), fixup_order);
+}
+
+static unsigned xtensa_find_first_cached_fixup (const fixup_cacheS *cache,
+						int addr)
+{
+  unsigned a = 0;
+  unsigned b = cache->n_fixups;
+
+  while (b - a > 1)
+    {
+      unsigned c = (a + b) / 2;
+
+      if (cache->fixups[c].addr < addr)
+	a = c;
+      else
+	b = c;
+    }
+  return a;
+}
+
+static void xtensa_delete_cached_fixup (fixup_cacheS *cache, unsigned i)
+{
+  memmove (cache->fixups + i, cache->fixups + i + 1,
+	   (cache->n_fixups - i - 1) * sizeof (*cache->fixups));
+  --cache->n_fixups;
+}
+
+static bfd_boolean xtensa_add_cached_fixup (fixup_cacheS *cache, fixS *fixP)
+{
+  cached_fixupS o;
+  unsigned i;
+
+  if (!xtensa_make_cached_fixup (&o, fixP))
+    return FALSE;
+  xtensa_realloc_fixup_cache (cache, 1);
+  i = xtensa_find_first_cached_fixup (cache, o.addr);
+  if (i < cache->n_fixups)
+    {
+      ++i;
+      memmove (cache->fixups + i + 1, cache->fixups + i,
+	       (cache->n_fixups - i) * sizeof (*cache->fixups));
+    }
+  cache->fixups[i] = o;
+  ++cache->n_fixups;
+  return TRUE;
+}
 
 /* Return the number of bytes added to this fragment, given that the
    input has been stretched already by "stretch".  */
@@ -8896,35 +9044,43 @@ xtensa_relax_frag (fragS *fragP, long stretch, int *stretched_p)
     case RELAX_TRAMPOLINE:
       if (fragP->tc_frag_data.relax_seen)
         {
-          segment_info_type *seginfo = seg_info (now_seg);
-          fragS *fP; /* The out-of-range jump.  */
-          fixS *fixP;
+	  static fixup_cacheS fixup_cache;
+	  segment_info_type *seginfo = seg_info (now_seg);
+	  int trampaddr = fragP->fr_address + fragP->fr_fix;
+	  int searchaddr = trampaddr < J_RANGE ? 0 : trampaddr - J_RANGE;
+	  unsigned i;
+
+	  if (now_seg != fixup_cache.seg ||
+	      fragP == fixup_cache.first_frag ||
+	      fixup_cache.first_frag == NULL)
+	    {
+	      xtensa_cache_relaxable_fixups (&fixup_cache, seginfo);
+	      fixup_cache.seg = now_seg;
+	      fixup_cache.first_frag = fragP;
+	    }
 
           /* Scan for jumps that will not reach.  */
-          for (fixP = seginfo->fix_root; fixP ; fixP = fixP->fx_next)
+          for (i = xtensa_find_first_cached_fixup (&fixup_cache, searchaddr);
+	       i < fixup_cache.n_fixups; ++i)
+
             {
-              symbolS *s = fixP->fx_addsy;
-	      xtensa_opcode opcode;
-              int target;
-              int addr;
-              int delta;
-
-              if (fixP->fx_r_type < BFD_RELOC_XTENSA_SLOT0_OP ||
-                  fixP->fx_r_type > BFD_RELOC_XTENSA_SLOT14_OP)
-                continue;
-	      xtensa_insnbuf_from_chars (isa, trampoline_buf,
-					 (unsigned char *) fixP->fx_frag->fr_literal + fixP->fx_where,
-					 0);
-	      fmt = xtensa_format_decode (isa, trampoline_buf);
-	      gas_assert (fmt != XTENSA_UNDEFINED);
-	      slot = fixP->tc_fix_data.slot;
-	      xtensa_format_get_slot (isa, fmt, slot, trampoline_buf, trampoline_slotbuf);
-	      opcode = xtensa_opcode_decode (isa, fmt, slot, trampoline_slotbuf);
-	      if (opcode != xtensa_j_opcode)
+	      fixS *fixP = fixup_cache.fixups[i].fixP;
+	      int target = fixup_cache.fixups[i].target;
+	      int addr = fixup_cache.fixups[i].addr;
+	      int delta = fixup_cache.fixups[i].delta + stretch;
+
+	      trampaddr = fragP->fr_address + fragP->fr_fix;
+
+	      if ((addr + J_RANGE < trampaddr) ||
+		  abs (addr - trampaddr) < J_RANGE / 2)
 		continue;
-              target = S_GET_VALUE (s);
-              addr = fixP->fx_frag->fr_address;
-              delta = target - addr + stretch;
+	      if (addr > trampaddr + J_RANGE)
+		break;
+	      if (abs (delta) < J_RANGE)
+		continue;
+
+	      slot = fixP->tc_fix_data.slot;
+
               if (delta > J_RANGE  || delta < -1 * J_RANGE)
                 { /* Found an out-of-range jump; scan the list of trampolines for the best match.  */
 		  struct trampoline_seg *ts = find_trampoline_seg (now_seg);
@@ -8978,14 +9134,13 @@ xtensa_relax_frag (fragS *fragP, long stretch, int *stretched_p)
 		    }
 		  if (tf->fragP == fragP)
 		    {
-		      int trampaddr = fragP->fr_address + fragP->fr_fix;
-
 		      if (abs (addr - trampaddr) < J_RANGE)
 			{ /* The trampoline is in range of original; fix it!  */
 			  fixS *newfixP;
 			  int offset;
 			  TInsn insn;
 			  symbolS *lsym;
+			  fragS *fP; /* The out-of-range jump.  */
 
 			  new_stretch += init_trampoline_frag (tf);
 			  offset = fragP->fr_fix; /* Where to assemble the j insn.  */
@@ -9009,10 +9164,20 @@ xtensa_relax_frag (fragS *fragP, long stretch, int *stretched_p)
 			  newfixP->tc_fix_data.X_add_symbol = lsym;
 			  newfixP->tc_fix_data.X_add_number = offset;
 			  newfixP->tc_fix_data.slot = slot;
+
+			  xtensa_delete_cached_fixup (&fixup_cache, i);
+			  xtensa_add_cached_fixup (&fixup_cache, newfixP);
+
 			  /* Move the fix-up from the original j insn to this one.  */
 			  fixP->fx_frag = fragP;
 			  fixP->fx_where = fragP->fr_fix - 3;
 			  fixP->tc_fix_data.slot = 0;
+
+			  xtensa_add_cached_fixup (&fixup_cache, fixP);
+
+			  /* re-do current fixup */
+			  --i;
+
 			  /* Adjust the jump around this trampoline (if present).  */
 			  if (tf->fixP != NULL)
 			    {
@@ -9027,6 +9192,8 @@ xtensa_relax_frag (fragS *fragP, long stretch, int *stretched_p)
 			      fragP->fr_subtype = 0;
 			      /* Remove from the trampoline_list.  */
 			      prev->next = tf->next;
+			      if (fragP == fixup_cache.first_frag)
+				fixup_cache.first_frag = NULL;
 			      break;
 			    }
 			}