From: Stefan Schulze Frielinghaus <stefansf@linux.ibm.com>
Date: Fri, 12 Mar 2021 16:32:42 +0000 (+0100)
Subject: cprop_hardreg: Ensure replacement reg has compatible mode [PR99221]
X-Git-Tag: basepoints/gcc-12~482
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a28cc94a27529b3108ea85be9ef5557a3c95791d;p=thirdparty%2Fgcc.git

cprop_hardreg: Ensure replacement reg has compatible mode [PR99221]

In addition to the existing check also ask the target whether a
replacement register may be accessed in a different mode than it was set
before.

gcc/ChangeLog:

	* regcprop.c (find_oldest_value_reg): Ask target whether
	  different mode is fine for replacement register.
---

diff --git a/gcc/regcprop.c b/gcc/regcprop.c
index e1342f56bd12..02753a125107 100644
--- a/gcc/regcprop.c
+++ b/gcc/regcprop.c
@@ -474,7 +474,8 @@ find_oldest_value_reg (enum reg_class cl, rtx reg, struct value_data *vd)
 	(set (...) (reg:DI r9))
      Replacing r9 with r11 is invalid.  */
   if (mode != vd->e[regno].mode
-      && REG_NREGS (reg) > hard_regno_nregs (regno, vd->e[regno].mode))
+      && (REG_NREGS (reg) > hard_regno_nregs (regno, vd->e[regno].mode)
+	  || !REG_CAN_CHANGE_MODE_P (regno, mode, vd->e[regno].mode)))
     return NULL_RTX;
 
   for (i = vd->e[regno].oldest_regno; i != regno; i = vd->e[i].next_regno)