[pushed] read-rtl: Fix infinite loop while parsing [...]

[Richard Sandiford]

read_rtx_operand would spin endlessly for:

   (unspec [(...))] UNSPEC_FOO)

because read_nested_rtx does nothing if the next character is not '('.

Pushed after testing on aarch64-linux-gnu & x86_&4-linux-gnu.

Richard


gcc/
        * read-rtl.cc (read_rtx_operand): Avoid spinning endlessly for
        invalid [...] operands.
---
 gcc/read-rtl.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/read-rtl.cc b/gcc/read-rtl.cc
index 292f8b72d43..f3b5613dfdb 100644
--- a/gcc/read-rtl.cc
+++ b/gcc/read-rtl.cc
@@ -1896,8 +1896,10 @@ rtx_reader::read_rtx_operand (rtx return_rtx, int idx)
                repeat_count--;
                value = saved_rtx;
              }
-           else
+           else if (c == '(')
              value = read_nested_rtx ();
+           else
+             fatal_with_file_and_line ("unexpected character in vector");
 
            for (; repeat_count > 0; repeat_count--)
              {
-- 
2.25.1