[binutils-gdb] resolve gas shift expressions with large exponents to zero

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=44a178cc69a05d03bcde37a4f46e4e8e81287b84

commit 44a178cc69a05d03bcde37a4f46e4e8e81287b84
Author: Alan Modra <amodra@gmail.com>
Date:   Thu Jan 26 18:44:51 2023 +1030

    resolve gas shift expressions with large exponents to zero
    
            * expr.c (resolve_expression <O_left_shift, O_right_shift>): Resolve
            shifts exceeding bits in a valueT to zero.

Diff:
---
 gas/expr.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/gas/expr.c b/gas/expr.c
index ba3d2109b9d..794be6f09d8 100644
--- a/gas/expr.c
+++ b/gas/expr.c
@@ -2320,8 +2320,18 @@ resolve_expression (expressionS *expressionP)
 	    return 0;
 	  left = (offsetT) left % (offsetT) right;
 	  break;
-	case O_left_shift:		left <<= right; break;
-	case O_right_shift:		left >>= right; break;
+	case O_left_shift:
+	  if (right >= sizeof (left) * CHAR_BIT)
+	    left = 0;
+	  else
+	    left <<= right;
+	  break;
+	case O_right_shift:
+	  if (right >= sizeof (left) * CHAR_BIT)
+	    left = 0;
+	  else
+	    left >>= right;
+	  break;
 	case O_bit_inclusive_or:	left |= right; break;
 	case O_bit_or_not:		left |= ~right; break;
 	case O_bit_exclusive_or:	left ^= right; break;