Remove global call sets: caller-save.c

All caller-save.c uses of "|= fixed_reg_set" added in a previous patch
were redundant, since the sets are later ANDed with ~fixed_reg_set.

2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* caller-save.c (setup_save_areas): Remove redundant |s of
	fixed_reg_set.
	(save_call_clobbered_regs): Likewise.  Use the call ABI rather
	than call_used_or_fixed_regs to decide whether a REG_RETURNED
	value is useful.

From-SVN: r276313

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 86caf6e..d912a87 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,13 @@
 2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>
 
+       * caller-save.c (setup_save_areas): Remove redundant |s of
+       fixed_reg_set.
+       (save_call_clobbered_regs): Likewise.  Use the call ABI rather
+       than call_used_or_fixed_regs to decide whether a REG_RETURNED
+       value is useful.
+
+2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>
+
        * rtl.h (predefined_function_abi): Declare.
        (choose_hard_reg_mode): Take a pointer to a predefined_function_abi
        instead of a boolean call_save flag.

diff --git a/gcc/caller-save.c b/gcc/caller-save.c
index 10b6737..6945387 100644 (file)
--- a/gcc/caller-save.c
+++ b/gcc/caller-save.c
@@ -428,8 +428,6 @@ setup_save_areas (void)
       REG_SET_TO_HARD_REG_SET (hard_regs_to_save,
                               &chain->live_throughout);
       used_regs = insn_callee_abi (insn).full_reg_clobbers ();
-      /* ??? This preserves traditional behavior; it might not be needed.  */
-      used_regs |= fixed_reg_set;
 
       /* Record all registers set in this call insn.  These don't
         need to be saved.  N.B. the call insn might set a subreg
@@ -513,9 +511,6 @@ setup_save_areas (void)
          REG_SET_TO_HARD_REG_SET (hard_regs_to_save,
                                   &chain->live_throughout);
          used_regs = insn_callee_abi (insn).full_reg_clobbers ();
-         /* ??? This preserves traditional behavior; it might not
-            be needed.  */
-         used_regs |= fixed_reg_set;
 
          /* Record all registers set in this call insn.  These don't
             need to be saved.  N.B. the call insn might set a subreg
@@ -793,7 +788,6 @@ save_call_clobbered_regs (void)
            {
              unsigned regno;
              HARD_REG_SET hard_regs_to_save;
-             HARD_REG_SET call_def_reg_set;
              reg_set_iterator rsi;
              rtx cheap;
 
@@ -840,15 +834,12 @@ save_call_clobbered_regs (void)
              note_stores (insn, mark_set_regs, &this_insn_sets);
 
              /* Compute which hard regs must be saved before this call.  */
+             function_abi callee_abi = insn_callee_abi (insn);
              hard_regs_to_save &= ~(fixed_reg_set
                                     | this_insn_sets
                                     | hard_regs_saved);
              hard_regs_to_save &= savable_regs;
-             call_def_reg_set = insn_callee_abi (insn).full_reg_clobbers ();
-             /* ??? This preserves traditional behavior; it might not
-                be needed.  */
-             call_def_reg_set |= fixed_reg_set;
-             hard_regs_to_save &= call_def_reg_set;
+             hard_regs_to_save &= callee_abi.full_reg_clobbers ();
 
              for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
                if (TEST_HARD_REG_BIT (hard_regs_to_save, regno))
@@ -863,8 +854,8 @@ save_call_clobbered_regs (void)
              
              if (cheap
                  && HARD_REGISTER_P (cheap)
-                 && TEST_HARD_REG_BIT (call_used_or_fixed_regs,
-                                       REGNO (cheap)))
+                 && callee_abi.clobbers_reg_p (GET_MODE (cheap),
+                                               REGNO (cheap)))
                {
                  rtx dest, newpat;
                  rtx pat = PATTERN (insn);