[22/32] Remove global call sets: postreload.c

[Richard Sandiford]

The "|= fixed_regs" in reload_combine isn't necessary, since the
set is only used to determine which values have changed (rather than,
for example, which registers are available for use).

In reload_cse_move2add we can be accurate about which registers
are still available.  BLKmode indicates a continuation of the
previous register, and since clobbers_reg_p handles multi-register
values, it's enough to skip over BLKmode entries and just test the
start register.


2019-09-11  Richard Sandiford  <richard.sandif...@arm.com>

gcc/
        * postreload.c (reload_combine_recognize_pattern): Use crtl->abi
        when deciding whether a register is free for use after RA.
        (reload_combine): Remove unnecessary use of fixed_reg_set.
        (reload_cse_move2add): Use call_insn_abi to get the ABI of the
        call insn target.  Use reg_mode when testing whether a register
        is no longer available.

Index: gcc/postreload.c
===================================================================
--- gcc/postreload.c    2019-09-11 19:47:24.418262673 +0100
+++ gcc/postreload.c    2019-09-11 19:48:41.905716645 +0100
@@ -1136,7 +1136,8 @@ reload_combine_recognize_pattern (rtx_in
              if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], i)
                  && reg_state[i].use_index == RELOAD_COMBINE_MAX_USES
                  && reg_state[i].store_ruid <= reg_state[regno].use_ruid
-                 && (call_used_or_fixed_reg_p (i) || df_regs_ever_live_p (i))
+                 && (crtl->abi->clobbers_full_reg_p (i)
+                     || df_regs_ever_live_p (i))
                  && (!frame_pointer_needed || i != HARD_FRAME_POINTER_REGNUM)
                  && !fixed_regs[i] && !global_regs[i]
                  && hard_regno_nregs (i, GET_MODE (reg)) == 1
@@ -1332,9 +1333,6 @@ reload_combine (void)
        {
          rtx link;
          HARD_REG_SET used_regs = call_insn_abi (insn).full_reg_clobbers ();
-         /* ??? This preserves traditional behavior; it might not be
-            needed.  */
-         used_regs |= fixed_reg_set;
 
          for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
            if (TEST_HARD_REG_BIT (used_regs, r))
@@ -2126,12 +2124,13 @@ reload_cse_move2add (rtx_insn *first)
         unknown values.  */
       if (CALL_P (insn))
        {
+         function_abi abi = call_insn_abi (insn);
          for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; i--)
-           {
-             if (call_used_or_fixed_reg_p (i))
-               /* Reset the information about this register.  */
-               reg_mode[i] = VOIDmode;
-           }
+           if (reg_mode[i] != VOIDmode
+               && reg_mode[i] != BLKmode
+               && abi.clobbers_reg_p (reg_mode[i], i))
+             /* Reset the information about this register.  */
+             reg_mode[i] = VOIDmode;
        }
     }
   return changed;