From: Uros Bizjak <ubizjak@gmail.com>
Date: Tue, 18 May 2021 13:45:54 +0000 (+0200)
Subject: i386: Fix split_double_mode with paradoxical subreg [PR100626]
X-Git-Tag: basepoints/gcc-13~7435
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d39fbed75810fc7478842503ecb0268b85dc9c2e;p=thirdparty%2Fgcc.git

i386: Fix split_double_mode with paradoxical subreg [PR100626]

split_double_mode calls simplify_gen_subreg, which fails for the
high half of the paradoxical subreg.  Return temporary register
instead of NULL RTX in this case.

2021-05-18  Uroš Bizjak  <ubizjak@gmail.com>

gcc/
	PR target/100626
	* config/i386/i386-expand.c (split_double_mode): Return
	temporary register when simplify_gen_subreg fails with
	the high half od the paradoxical subreg.
---

diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c
index 0fa8d45a684e..9f3d41955a2f 100644
--- a/gcc/config/i386/i386-expand.c
+++ b/gcc/config/i386/i386-expand.c
@@ -154,9 +154,13 @@ split_double_mode (machine_mode mode, rtx operands[],
 	  lo_half[num] = simplify_gen_subreg (half_mode, op,
 					      GET_MODE (op) == VOIDmode
 					      ? mode : GET_MODE (op), 0);
-	  hi_half[num] = simplify_gen_subreg (half_mode, op,
-					      GET_MODE (op) == VOIDmode
-					      ? mode : GET_MODE (op), byte);
+
+	  rtx tmp = simplify_gen_subreg (half_mode, op,
+					 GET_MODE (op) == VOIDmode
+					 ? mode : GET_MODE (op), byte);
+	  /* simplify_gen_subreg will return NULL RTX for the
+	     high half of the paradoxical subreg. */
+	  hi_half[num] = tmp ? tmp : gen_reg_rtx (half_mode);
 	}
     }
 }