[gcc r12-7106] combine: Check for paradoxical subreg.

[Robin Dapp]

https://gcc.gnu.org/g:38a177fa4c2fd1ce75581145b3b8f12592b4aacd

commit r12-7106-g38a177fa4c2fd1ce75581145b3b8f12592b4aacd
Author: Robin Dapp <rdapp@linux.ibm.com>
Date:   Tue Feb 8 14:39:16 2022 +0100

    combine: Check for paradoxical subreg.
    
    This adds a check for a paradoxical subreg in reg_subword_p ()
    in order to prevent an ICE on s390 in try_combine () triggered
    by the movqicc expander.
    
    gcc/ChangeLog:
    
            * combine.cc (reg_subword_p): Check for paradoxical subreg.

Diff:
---
 gcc/combine.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gcc/combine.cc b/gcc/combine.cc
index 7683f8250fe..c264ededf20 100644
--- a/gcc/combine.cc
+++ b/gcc/combine.cc
@@ -2411,6 +2411,7 @@ reg_subword_p (rtx x, rtx reg)
     x = XEXP (x, 0);
 
   return GET_CODE (x) == SUBREG
+	 && !paradoxical_subreg_p (x)
 	 && SUBREG_REG (x) == reg
 	 && GET_MODE_CLASS (GET_MODE (x)) == MODE_INT;
 }