params.def (PARAM_MAX_PENDING_LIST_LENGTH): Add parameter to limit length of dependan...

2001-07-26  Andrew MacLeod  <amacleod@redhat.com>

	* params.def (PARAM_MAX_PENDING_LIST_LENGTH): Add parameter to
	limit length of dependancy flush list.
	* params.h (MAX_PENDING_LIST_LENGTH): Define.
	* sched-int.h  (struct deps): Add pending_flush_length field.
	* sched-deps.c (flush_pending_lists): Last_pending_memory_flush now
	has 1 element in it.
	(sched_analyze_1): Use MAX_PENDING_LIST_LENGTH.
	(sched_analyze): After a jump, if the pending memory flush list is too
	large, flush the pending lists.
	(init_deps): Initialize pending_flush_length to 0.
	* doc/invoke.texi (max_pending_list_length): Document parameter.

From-SVN: r44398

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aad462cc72a5557f36728c73d7656ca3a826048c..8bc87889e78ca5b0fbd3147df3f3a523d7352035 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2001-07-26  Andrew MacLeod  <amacleod@redhat.com>
+
+       * params.def (PARAM_MAX_PENDING_LIST_LENGTH): Add parameter to 
+       limit length of dependancy flush list.
+       * params.h (MAX_PENDING_LIST_LENGTH): Define.
+       * sched-int.h  (struct deps): Add pending_flush_length field.
+       * sched-deps.c (flush_pending_lists): Last_pending_memory_flush now
+       has 1 element in it.
+       (sched_analyze_1): Use MAX_PENDING_LIST_LENGTH.
+       (sched_analyze): After a jump, if the pending memory flush list is too
+       large, flush the pending lists.
+       (init_deps): Initialize pending_flush_length to 0.
+       * doc/invoke.texi (max_pending_list_length): Document parameter.
+
 2001-07-26  Neil Booth  <neil@daikokuya.demon.co.uk>
 
        * toplev.c, varasm.c, final.c: Include xcoffout.h if appropriate.

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3b13ad81dfcdec90a39ebef16eea7c021d22aa94..f3b3e8e26f02d348c39d65d2280f4377bafc6517 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3808,6 +3808,12 @@ optimization will not be done.
 @item max-gcse-passes
 The maximum number of passes of GCSE to run.
 
+@item max-pending-list-length
+The maximum number of pending dependancies scheduling will allow
+before flushing the current state and starting over.  Large functions
+with few branches or calls can create excessively large lists which
+needlessly consume memory and resources.
+
 @item max-inline-insns
 If an function contains more than this many instructions, it
 will not be inlined.  This option is precisely equivalent to

diff --git a/gcc/params.def b/gcc/params.def
index d7e9bc07c42dd033a196f321c1be502746a76b14..ca952c1b35661458a9e9a5a7f88dbd478d553025 100644 (file)
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -68,6 +68,16 @@ DEFPARAM(PARAM_MAX_DELAY_SLOT_LIVE_SEARCH,
         "The maximum number of instructions to consider to find accurate live register information",
         333)
 
+/* This parameter limits the number of branch elements that the 
+   scheduler will track anti-dependancies through without resetting
+   the tracking mechanism.  Large functions with few calls or barriers 
+   can generate lists containing many 1000's of dependancies.  Generally 
+   the compiler either uses all available memory, or runs for far too long.  */
+DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
+        "max-pending-list-length",
+        "The maximum length of scheduling's pending operations list",
+        32)
+
 /* The GCSE optimization will be disabled if it would require
    significantly more memory than this value.  */
 DEFPARAM(PARAM_MAX_GCSE_MEMORY,

diff --git a/gcc/params.h b/gcc/params.h
index 2b29094a6f23235b34a075a67f144f3b83a54cdb..e8eb285275ca1577da6c511b177b2cedd3f767b0 100644 (file)
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -90,6 +90,8 @@ typedef enum compiler_param
   PARAM_VALUE (PARAM_MAX_DELAY_SLOT_INSN_SEARCH)
 #define MAX_DELAY_SLOT_LIVE_SEARCH \
   PARAM_VALUE (PARAM_MAX_DELAY_SLOT_LIVE_SEARCH)
+#define MAX_PENDING_LIST_LENGTH \
+  PARAM_VALUE (PARAM_MAX_PENDING_LIST_LENGTH)
 #define MAX_GCSE_MEMORY \
   ((size_t) PARAM_VALUE (PARAM_MAX_GCSE_MEMORY))
 #define MAX_GCSE_PASSES \

diff --git a/gcc/sched-deps.c b/gcc/sched-deps.c
index 422b39485d36f8bbe65e70eed9de9850a5983146..3f4b1290d7c9a490084a83539047738d4556e2d8 100644 (file)
--- a/gcc/sched-deps.c
+++ b/gcc/sched-deps.c
@@ -38,6 +38,7 @@ the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "toplev.h"
 #include "recog.h"
 #include "sched-int.h"
+#include "params.h"
 
 extern char *reg_known_equiv_p;
 extern rtx *reg_known_value;
@@ -534,6 +535,7 @@ flush_pending_lists (deps, insn, only_write)
 
   free_INSN_LIST_list (&deps->last_pending_memory_flush);
   deps->last_pending_memory_flush = alloc_INSN_LIST (insn, NULL_RTX);
+  deps->pending_flush_length = 1;
 }
 \f
 /* Analyze a single SET, CLOBBER, PRE_DEC, POST_DEC, PRE_INC or POST_INC
@@ -675,14 +677,13 @@ sched_analyze_1 (deps, x, insn)
     {
       /* Writing memory.  */
 
-      if (deps->pending_lists_length > 32)
+      if (deps->pending_lists_length > MAX_PENDING_LIST_LENGTH)
        {
          /* Flush all pending reads and writes to prevent the pending lists
             from getting any larger.  Insn scheduling runs too slowly when
-            these lists get long.  The number 32 was chosen because it
-            seems like a reasonable number.  When compiling GCC with itself,
+            these lists get long.  When compiling GCC with itself,
             this flush occurs 8 times for sparc, and 10 times for m88k using
-            the number 32.  */
+            the default value of 32.  */
          flush_pending_lists (deps, insn, 0);
        }
       else
@@ -1246,8 +1247,14 @@ sched_analyze (deps, head, tail)
          /* Make each JUMP_INSN a scheduling barrier for memory
              references.  */
          if (GET_CODE (insn) == JUMP_INSN)
-           deps->last_pending_memory_flush
-             = alloc_INSN_LIST (insn, deps->last_pending_memory_flush);
+           {
+             /* Keep the list a reasonable size.  */
+             if (deps->pending_flush_length++ > MAX_PENDING_LIST_LENGTH)
+               flush_pending_lists (deps, insn, 0);
+             else
+               deps->last_pending_memory_flush
+                 = alloc_INSN_LIST (insn, deps->last_pending_memory_flush);
+           }
          sched_analyze_insn (deps, PATTERN (insn), insn, loop_notes);
          loop_notes = 0;
        }
@@ -1473,6 +1480,7 @@ init_deps (deps)
   deps->pending_write_insns = 0;
   deps->pending_write_mems = 0;
   deps->pending_lists_length = 0;
+  deps->pending_flush_length = 0;
   deps->last_pending_memory_flush = 0;
   deps->last_function_call = 0;
   deps->in_post_call_group_p = 0;

diff --git a/gcc/sched-int.h b/gcc/sched-int.h
index 0eb2e6682797cfb115dcc2ad9c97a7ce6877000b..0b7ebab08d76b5dcbc292577aacd2b693fd55690 100644 (file)
--- a/gcc/sched-int.h
+++ b/gcc/sched-int.h
@@ -53,6 +53,10 @@ struct deps
      a function of the length of these pending lists.  */
   int pending_lists_length;
 
+  /* Length of the pending memory flush list. Large functions with no
+     calls may build up extremely large lists.  */
+  int pending_flush_length;
+
   /* The last insn upon which all memory references must depend.
      This is an insn which flushed the pending lists, creating a dependency
      between it and all previously pending memory references.  This creates