regmove.c (optimize_reg_copy_1): Undo Aug 18 change.

	* regmove.c (optimize_reg_copy_1): Undo Aug 18 change.  Update
	REG_N_CALLS_CROSSED and REG_LIVE_LENGH if and only if we change
	where a register is live.

From-SVN: r24717

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 688008488b522f158b636ea89c438ca768f4db9d..16e71423e724c09a819aaeacd8a76bc1cd67ec35 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+Sun Jan 17 19:01:47 1999  Jeffrey A Law  (law@cygnus.com)
+
+       * regmove.c (optimize_reg_copy_1): Undo Aug 18 change.  Update
+       REG_N_CALLS_CROSSED and REG_LIVE_LENGH if and only if we change
+       where a register is live.
+
 Fri Jan 15 01:19:42 1999  Jeffrey A Law  (law@cygnus.com)
 
        * unroll.c (find_splittable_givs): For a DEST_ADDR giv, do not share

diff --git a/gcc/regmove.c b/gcc/regmove.c
index 0a598912d5043d036010b414cb5183747e4a9bd7..605169a5d82a1d77d0a278d94db368d330af94c6 100644 (file)
--- a/gcc/regmove.c
+++ b/gcc/regmove.c
@@ -1,5 +1,5 @@
 /* Move registers around to reduce number of move instructions needed.
-   Copyright (C) 1987, 88, 89, 92-97, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1987, 88, 89, 92-98, 1999 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -254,10 +254,10 @@ optimize_reg_copy_1 (insn, dest, src)
          && GET_MODE (XEXP (note, 0)) == GET_MODE (src))
        {
          int failed = 0;
-         int length = 0;
          int d_length = 0;
-         int n_calls = 0;
+         int s_length = 0;
          int d_n_calls = 0;
+         int s_n_calls = 0;
 
          /* We can do the optimization.  Scan forward from INSN again,
             replacing regs as we go.  Set FAILED if a replacement can't
@@ -291,42 +291,14 @@ optimize_reg_copy_1 (insn, dest, src)
                         insn in the REG_N_REFS updates below.  If this is not
                         correct, no great harm is done.
 
-
-                        We do not undo this substitution if something later
-                        fails.  Therefore, we must update the other REG_N_*
-                        counters now to keep them accurate.  */
+                        Since we do not know if we will change the lifetime of
+                        SREGNO or DREGNO, we must not update REG_LIVE_LENGTH
+                        or REG_N_CALLS_CROSSED at this time.   */
                      if (sregno >= FIRST_PSEUDO_REGISTER)
-                       {
-                         REG_N_REFS (sregno) -= loop_depth;
-
-                         if (REG_LIVE_LENGTH (sregno) >= 0)
-                           {
-                             REG_LIVE_LENGTH (sregno) -= length;
-                             /* REG_LIVE_LENGTH is only an approximation after
-                                combine if sched is not run, so make sure that
-                                we still have a reasonable value.  */
-                             if (REG_LIVE_LENGTH (sregno) < 2)
-                               REG_LIVE_LENGTH (sregno) = 2;
-                           }
-
-                         REG_N_CALLS_CROSSED (sregno) -= n_calls;
-                       }
+                       REG_N_REFS (sregno) -= loop_depth;
 
                      if (dregno >= FIRST_PSEUDO_REGISTER)
-                       {
-                         REG_N_REFS (dregno) += loop_depth;
-
-                         if (REG_LIVE_LENGTH (dregno) >= 0)
-                           REG_LIVE_LENGTH (dregno) += d_length;
-
-                         REG_N_CALLS_CROSSED (dregno) += d_n_calls;
-                       }
-
-                     /* We've done a substitution, clear the counters.  */
-                     length = 0;
-                     d_length = 0;
-                     n_calls = 0;
-                     d_n_calls = 0;
+                       REG_N_REFS (dregno) += loop_depth;
                    }
                  else
                    {
@@ -335,9 +307,10 @@ optimize_reg_copy_1 (insn, dest, src)
                    }
                }
 
-             /* Count the insns and CALL_INSNs passed.  If we passed the
-                death note of DEST, show increased live length.  */
-             length++;
+             /* For SREGNO, count the total number of insns scanned.
+                For DREGNO, count the total number of insns scanned after
+                passing the death note for DREGNO.  */
+             s_length++;
              if (dest_death)
                d_length++;
 
@@ -345,7 +318,9 @@ optimize_reg_copy_1 (insn, dest, src)
                 as a call that has been crossed.  Otherwise, count it.  */
              if (q != p && GET_CODE (q) == CALL_INSN)
                {
-                 n_calls++;
+                 /* Similarly, total calls for SREGNO, total calls beyond
+                    the death note for DREGNO.  */
+                 s_n_calls++;
                  if (dest_death)
                    d_n_calls++;
                }
@@ -365,11 +340,13 @@ optimize_reg_copy_1 (insn, dest, src)
 
          if (! failed)
            {
+             /* These counters need to be updated if and only if we are
+                going to move the REG_DEAD note.  */
              if (sregno >= FIRST_PSEUDO_REGISTER)
                {
                  if (REG_LIVE_LENGTH (sregno) >= 0)
                    {
-                     REG_LIVE_LENGTH (sregno) -= length;
+                     REG_LIVE_LENGTH (sregno) -= s_length;
                      /* REG_LIVE_LENGTH is only an approximation after
                         combine if sched is not run, so make sure that we
                         still have a reasonable value.  */
@@ -377,15 +354,7 @@ optimize_reg_copy_1 (insn, dest, src)
                        REG_LIVE_LENGTH (sregno) = 2;
                    }
 
-                 REG_N_CALLS_CROSSED (sregno) -= n_calls;
-               }
-
-             if (dregno >= FIRST_PSEUDO_REGISTER)
-               {
-                 if (REG_LIVE_LENGTH (dregno) >= 0)
-                   REG_LIVE_LENGTH (dregno) += d_length;
-
-                 REG_N_CALLS_CROSSED (dregno) += d_n_calls;
+                 REG_N_CALLS_CROSSED (sregno) -= s_n_calls;
                }
 
              /* Move death note of SRC from P to INSN.  */
@@ -399,6 +368,15 @@ optimize_reg_copy_1 (insn, dest, src)
            {
              XEXP (dest_death, 1) = REG_NOTES (p);
              REG_NOTES (p) = dest_death;
+
+             if (dregno >= FIRST_PSEUDO_REGISTER)
+               {
+                 /* If and only if we are moving the death note for DREGNO,
+                    then we need to update its counters.  */
+                 if (REG_LIVE_LENGTH (dregno) >= 0)
+                   REG_LIVE_LENGTH (dregno) += d_length;
+                 REG_N_CALLS_CROSSED (dregno) += d_n_calls;
+               }
            }
 
          return ! failed;