[PATCH] Remove a couple of VLAs

[PATCH] Remove a couple of VLAs

[Tom Tromey]

I found a couple of spots where VLAs are in use but where they can
easily be removed.

In one spot, adding 'const' is enough -- and is already done in
similar code elsewhere in the file.

In another spot, one of two arrays will be used, so making the buffer
large enough for both works.
---
 gdb/aarch64-tdep.c   | 2 +-
 gdb/arc-linux-tdep.c | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index 545ec872fd8..06eda102468 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -5713,7 +5713,7 @@ aarch64_process_record (struct gdbarch *gdbarch, struct regcache *regcache,
 			CORE_ADDR insn_addr)
 {
   uint32_t rec_no = 0;
-  uint8_t insn_size = 4;
+  const uint8_t insn_size = 4;
   uint32_t ret = 0;
   gdb_byte buf[insn_size];
   aarch64_insn_decode_record aarch64_record;
diff --git a/gdb/arc-linux-tdep.c b/gdb/arc-linux-tdep.c
index 54406ac5b90..30bd40c8027 100644
--- a/gdb/arc-linux-tdep.c
+++ b/gdb/arc-linux-tdep.c
@@ -174,6 +174,9 @@ arc_linux_is_sigtramp (const frame_info_ptr &this_frame)
     0x22, 0x6f, 0x00, 0x3f	/* swi */
   };
 
+  constexpr size_t max_insn_sz = std::max (sizeof (insns_be_hs),
+					   sizeof (insns_be_700));
+
   gdb_byte arc_sigtramp_insns[sizeof (insns_be_700)];
   size_t insns_sz;
   if (arc_mach_is_arcv2 (gdbarch))
@@ -200,7 +203,8 @@ arc_linux_is_sigtramp (const frame_info_ptr &this_frame)
 	std::swap (arc_sigtramp_insns[i], arc_sigtramp_insns[i+1]);
     }
 
-  gdb_byte buf[insns_sz];
+  gdb_assert (insns_sz <= max_insn_sz);
+  gdb_byte buf[max_insn_sz];
 
   /* Read the memory at the PC.  Since we are stopped, any breakpoint must
      have been removed.  */
-- 
2.44.0

Re: [PATCH] Remove a couple of VLAs

[John Baldwin]

On 4/17/24 4:01 PM, Tom Tromey wrote:
> I found a couple of spots where VLAs are in use but where they can
> easily be removed.
> 
> In one spot, adding 'const' is enough -- and is already done in
> similar code elsewhere in the file.
> 
> In another spot, one of two arrays will be used, so making the buffer
> large enough for both works.

Approved-By: John Baldwin <jhb@FreeBSD.org>

-- 
John Baldwin