[gdb/tdep] Fix rip-relative insn handling in amd64_get_used_input_int_reg

I wanted to add a unit test for an an rip-relative amd64 insn, so I did:
...
$ gcc -fPIE hello.c
...
and used an rip-relative insn from main:
...
  4005db:       48 8d 3d 1e 00 00 00    lea    0x1e(%rip),%rdi
...

While writing the unit test, I found that amd64_get_used_input_int_reg returns
rbp as input register.

Fix this by using rip_relative_p in amd64_get_used_input_int_reg to handle
this case.

Tested on x86_64-linux.

diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index a2da1392cddaefdb68178c0986c3e223eaa424f9..09f41e5393e7b655831639f4e2a5ade4e181ec71 100644 (file)
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -1264,7 +1264,7 @@ amd64_get_used_input_int_regs (const struct amd64_insn *details,
          used_regs_mask |= 1 << base;
          used_regs_mask |= 1 << idx;
        }
-      else
+      else if (!rip_relative_p (modrm))
        {
          used_regs_mask |= 1 << rm;
        }
@@ -3447,6 +3447,17 @@ test_amd64_get_insn_details (void)
   SELF_CHECK (amd64_get_used_input_int_regs (&details, false)
              == ((1 << EAX_REG_NUM)));
   SELF_CHECK (rip_relative_offset (&details) == 0);
+
+  /* INSN: lea 0x1e(%rip),%rdi, rex prefix.  */
+  insn = { 0x48, 0x8d, 0x3d, 0x1e, 0x00, 0x00, 0x00 };
+  amd64_get_insn_details (insn.data (), &details);
+  SELF_CHECK (details.opcode_len == 1);
+  SELF_CHECK (details.enc_prefix_offset == 0);
+  SELF_CHECK (details.opcode_offset == 1);
+  SELF_CHECK (details.modrm_offset == 2);
+  SELF_CHECK (amd64_get_used_input_int_regs (&details, false)
+             == (1 << EDI_REG_NUM));
+  SELF_CHECK (rip_relative_offset (&details) == 3);
 }
 
 static void