Remove global call sets: cselib.c

cselib_invalidate_regno is a no-op if REG_VALUES (i) is null,
so we can check that first.  Then, if we know what mode the register
currently has, we can check whether it's clobbered in that mode.

Using GET_MODE (values->elt->val_rtx) to get the mode of the last
set is taken from cselib_reg_set_mode.

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

gcc/
	* cselib.c (cselib_process_insn): If we know what mode a
	register was set in, check whether it is clobbered in that
	mode by a call.  Only fall back to reg_raw_mode if that fails.

From-SVN: r276318

gcc/ChangeLog

 2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* cselib.c (cselib_process_insn): If we know what mode a
+	register was set in, check whether it is clobbered in that
+	mode by a call.  Only fall back to reg_raw_mode if that fails.
+
+2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* cse.c: Include regs.h and function-abi.h.
 	(invalidate_for_call): Take the call insn as an argument.
 	Use insn_callee_abi to get the ABI of the call and invalidate

gcc/cselib.c

@@ -2768,12 +2768,24 @@ cselib_process_insn (rtx_insn *insn)
     {
       function_abi callee_abi = insn_callee_abi (insn);
       for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
-	if (call_used_or_fixed_reg_p (i)
-	    || (REG_VALUES (i) && REG_VALUES (i)->elt
-		&& (targetm.hard_regno_call_part_clobbered
-		    (callee_abi.id (), i,
-		     GET_MODE (REG_VALUES (i)->elt->val_rtx)))))
-	  cselib_invalidate_regno (i, reg_raw_mode[i]);
+	if (elt_list *values = REG_VALUES (i))
+	  {
+	    /* If we know what mode the value was set in, check whether
+	       it is still available after the call in that mode.  If we
+	       don't know the mode, we have to check for the worst-case
+	       scenario instead.  */
+	    if (values->elt)
+	      {
+		machine_mode mode = GET_MODE (values->elt->val_rtx);
+		if (callee_abi.clobbers_reg_p (mode, i))
+		  cselib_invalidate_regno (i, mode);
+	      }
+	    else
+	      {
+		if (callee_abi.clobbers_at_least_part_of_reg_p (i))
+		  cselib_invalidate_regno (i, reg_raw_mode[i]);
+	      }
+	  }
 
       /* Since it is not clear how cselib is going to be used, be
 	 conservative here and treat looping pure or const functions