[binutils-gdb] Fix -Wmaybe-uninitialized warning in opcodes/i386-dis.c

[Tom Tromey <tromey@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=da9a978aae78e2c1e35ccdf683474847e4465e5f

commit da9a978aae78e2c1e35ccdf683474847e4465e5f
Author: Tom Tromey <tromey@adacore.com>
Date:   Fri Apr 21 07:05:53 2023 -0600

    Fix -Wmaybe-uninitialized warning in opcodes/i386-dis.c
    
    A recent change in opcodes/i386-dis.c caused a build failure on my
    x86-64 Fedora 36 system, which uses:
    
    $ gcc --version
    gcc (GCC) 12.2.1 20221121 (Red Hat 12.2.1-4)
    [...]
    
    The error is:
    
    ../../binutils-gdb/opcodes/i386-dis.c: In function ‘OP_J’:
    ../../binutils-gdb/opcodes/i386-dis.c:12705:22: error: ‘val’ may be used uninitialized [-Werror=maybe-uninitialized]
    12705 |           disp = val & 0x8000 ? val - 0x10000 : val;
          |                  ~~~~^~~~~~~~
    
    This patch fixes the warning.
    
    opcodes/ChangeLog
    2023-04-21  Tom Tromey  <tromey@adacore.com>
    
            * i386-dis.c (OP_J): Check result of get16.

Diff:
---
 opcodes/ChangeLog  | 4 ++++
 opcodes/i386-dis.c | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index d0c338a0f6d..890931e6b8a 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,3 +1,7 @@
+2023-04-21  Tom Tromey  <tromey@adacore.com>
+
+	* i386-dis.c (OP_J): Check result of get16.
+
 2023-04-12  Claudiu Zissulescu  <claziss@synopsys.com>
 
 	* arc-tbl.h: Remove vadds2, vadds2h, vadds4h, vaddsubs,
diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 46ba01fe093..f021bdaa3e7 100644
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -12701,7 +12701,8 @@ OP_J (instr_info *ins, int bytemode, int sizeflag)
 	{
 	  int val;
 
-	  get16 (ins, &val);
+	  if (!get16 (ins, &val))
+	    return false;
 	  disp = val & 0x8000 ? val - 0x10000 : val;
 	  /* In 16bit mode, address is wrapped around at 64k within
 	     the same segment.  Otherwise, a data16 prefix on a jump