[gdb/tdep] Fix recording of T1 push

When running test-case gdb.reverse/recursion.exp on arm-linux with target
board unix/-mthumb, I run into:
...
(gdb) PASS: gdb.reverse/recursion.exp: Skipping recursion from inside
reverse-next^M
bar (x=4195569) at /home/linux/gdb/src/gdb/testsuite/gdb.reverse/recursion.c:34^M
34        int r = foo (x);^M
(gdb) FAIL: gdb.reverse/recursion.exp: print frame when stepping out
...

The problem is the recording of the T1 push instruction [1,2], specifically:
...
000004d8 <foo>:
 4d8:   b580            push    {r7, lr}
...

The current code fails to add a memory record for the memory written with the
value of the lr register.

Fix this by adding the missing memory record.

Tested on arm-linux.

Reviewed-By: Guinevere Larsen <guinevere@redhat.com>
Approved-By: Luis Machado <luis.machado@arm.com>
[1] https://developer.arm.com/documentation/ddi0406/c/Application-Level-Architecture/Instruction-Details/Encoding-of-lists-of-ARM-core-registers
[2] https://developer.arm.com/documentation/ddi0597/2024-09/T32-Instructions-by-Encoding/16-bit?lang=en#pushpop16

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 9c996b821be64727fd4480d510129c7cb47c60a9..34507615975ad0ff61c240ed68ec31a8ec827521 100644 (file)
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -13557,9 +13557,12 @@ thumb_record_misc (arm_insn_decode_record *thumb_insn_r)
          record_buf[0] = bits (thumb_insn_r->arm_insn, 0, 2);
          thumb_insn_r->reg_rec_count = 1;
          break;
-       case 4: /* fall through  */
        case 5:
-         /* PUSH.  */
+         /* PUSH with lr.  */
+         register_count++;
+         [[fallthrough]];
+       case 4:
+         /* PUSH without lr.  */
          register_bits = bits (thumb_insn_r->arm_insn, 0, 7);
          regcache_raw_read_unsigned (reg_cache, ARM_SP_REGNUM, &u_regval);
          while (register_bits)
@@ -13568,8 +13571,7 @@ thumb_record_misc (arm_insn_decode_record *thumb_insn_r)
                register_count++;
              register_bits = register_bits >> 1;
            }
-         start_address = u_regval -  \
-           (4 * (bit (thumb_insn_r->arm_insn, 8) + register_count));
+         start_address = u_regval - (4 * register_count);
          thumb_insn_r->mem_rec_count = register_count;
          while (register_count)
            {