(reg_equiv_replace): New variable.

(update_equiv_regs): Set reg_equiv_replacement for all REG_EQUIV
notes encountered or generated.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@12618 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 35 insertions, 21 deletions

diff --git a/gcc/local-alloc.c b/gcc/local-alloc.c
index 156fe92d537..de19b2fd88d 100644
--- a/gcc/local-alloc.c
+++ b/gcc/local-alloc.c
@@ -236,7 +236,10 @@ static int this_insn_number;
 static rtx this_insn;
 
 /* Used to communicate changes made by update_equiv_regs to
-   memref_referenced_p.  */
+   memref_referenced_p.  reg_equiv_replacement is set for any REG_EQUIV note
+   found or created, so that we can keep track of what memory accesses might
+   be created later, e.g. by reload.  */
+
 static rtx *reg_equiv_replacement;
 
 static void alloc_qty		PROTO((int, enum machine_mode, int, int));
@@ -955,12 +958,17 @@ static void
 update_equiv_regs ()
 {
   rtx *reg_equiv_init_insn = (rtx *) alloca (max_regno * sizeof (rtx *));
+  /* Set when an attempt should be made to replace a register with the
+     associated reg_equiv_replacement entry at the end of this function.  */
+  char *reg_equiv_replace
+    = (char *) alloca (max_regno * sizeof *reg_equiv_replace);
   rtx insn;
 
   reg_equiv_replacement = (rtx *) alloca (max_regno * sizeof (rtx *));
 
   bzero ((char *) reg_equiv_init_insn, max_regno * sizeof (rtx *));
   bzero ((char *) reg_equiv_replacement, max_regno * sizeof (rtx *));
+  bzero ((char *) reg_equiv_replace, max_regno * sizeof *reg_equiv_replace);
 
   init_alias_analysis ();
 
@@ -1069,32 +1077,38 @@ update_equiv_regs ()
 	REG_NOTES (insn) = note = gen_rtx (EXPR_LIST, REG_EQUIV, SET_SRC (set),
 					   REG_NOTES (insn));
 
-      /* Don't mess with things live during setjmp.  */
-      if (note && reg_live_length[regno] >= 0)
+      if (note)
 	{
 	  int regno = REGNO (dest);
 
-	  /* Note that the statement below does not affect the priority
-	     in local-alloc!  */
-	  reg_live_length[regno] *= 2;
+	  reg_equiv_replacement[regno] = XEXP (note, 0);
+
+	  /* Don't mess with things live during setjmp.  */
+	  if (reg_live_length[regno] >= 0)
+	    {
+	      /* Note that the statement below does not affect the priority
+		 in local-alloc!  */
+	      reg_live_length[regno] *= 2;
 
-	  /* If the register is referenced exactly twice, meaning it is set
-	     once and used once, indicate that the reference may be replaced
-	     by the equivalence we computed above.  If the register is only
-	     used in one basic block, this can't succeed or combine would
-	     have done it.
 
-	     It would be nice to use "loop_depth * 2" in the compare
-	     below.  Unfortunately, LOOP_DEPTH need not be constant within
-	     a basic block so this would be too complicated.
+	      /* If the register is referenced exactly twice, meaning it is
+		 set once and used once, indicate that the reference may be
+		 replaced by the equivalence we computed above.  If the
+		 register is only used in one basic block, this can't succeed
+		 or combine would have done it.
 
-	     This case normally occurs when a parameter is read from memory
-	     and then used exactly once, not in a loop.  */
+		 It would be nice to use "loop_depth * 2" in the compare
+		 below.  Unfortunately, LOOP_DEPTH need not be constant within
+		 a basic block so this would be too complicated.
 
-	  if (reg_n_refs[regno] == 2
-	      && reg_basic_block[regno] < 0
-	      && rtx_equal_p (XEXP (note, 0), SET_SRC (set)))
-	    reg_equiv_replacement[regno] = SET_SRC (set);
+		 This case normally occurs when a parameter is read from
+		 memory and then used exactly once, not in a loop.  */
+
+		if (reg_n_refs[regno] == 2
+		    && reg_basic_block[regno] < 0
+		    && rtx_equal_p (XEXP (note, 0), SET_SRC (set)))
+		  reg_equiv_replace[regno] = 1;
+	    }
 	}
     }
 
@@ -1115,7 +1129,7 @@ update_equiv_regs ()
 	  {
 	    int regno = REGNO (XEXP (link, 0));
 
-	    if (reg_equiv_replacement[regno]
+	    if (reg_equiv_replace[regno]
 		&& validate_replace_rtx (regno_reg_rtx[regno],
 					 reg_equiv_replacement[regno], insn))
 	      {