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[PATCH] Improve spillcost of literal pool loads


This patch adjusts the spill cost of literal pool loads to reduce the chance of them being
caller-saved (which is inefficient). Such loads should be rematerialized and thus should not include
the cost of a spill store. This was done only on constants for which legitimate_constant_p is true,
however it is right thing to do for any constant, including constants in literal pools (which are
typically not legitimate). Also use ALL_REGS rather than GENERAL_REGS as ALL_REGS has the correct
floating point register costs.

ChangeLog:
2014-10-29  Wilco Dijkstra  <wdijkstr@arm.com>

	* gcc/ira-costs.c (scan_one_insn): Improve spill cost adjustment.

---
 gcc/ira-costs.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/gcc/ira-costs.c b/gcc/ira-costs.c
index 122815b..c4a1934 100644
--- a/gcc/ira-costs.c
+++ b/gcc/ira-costs.c
@@ -1455,19 +1455,18 @@ scan_one_insn (rtx_insn *insn)
      mem_cost might result in it being loaded using the specialized
      instruction into a register, then stored into stack and loaded
      again from the stack.  See PR52208.
-     
+
      Don't do this if SET_SRC (set) has side effect.  See PR56124.  */
   if (set != 0 && REG_P (SET_DEST (set)) && MEM_P (SET_SRC (set))
       && (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != NULL_RTX
       && ((MEM_P (XEXP (note, 0))
 	   && !side_effects_p (SET_SRC (set)))
 	  || (CONSTANT_P (XEXP (note, 0))
-	      && targetm.legitimate_constant_p (GET_MODE (SET_DEST (set)),
-						XEXP (note, 0))
+	      && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (XEXP (note, 0)))
 	      && REG_N_SETS (REGNO (SET_DEST (set))) == 1))
       && general_operand (SET_SRC (set), GET_MODE (SET_SRC (set))))
     {
-      enum reg_class cl = GENERAL_REGS;
+      enum reg_class cl = ALL_REGS;
       rtx reg = SET_DEST (set);
       int num = COST_INDEX (REGNO (reg));
 
-- 
1.9.1



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