[Tarantool-patches] [PATCH luajit] x64: Properly fix __call metamethod return dispatch.

[Sergey Kaplun]

From: Mike Pall <mike>

Reported by Sergey Kaplun.

(cherry-picked from commit d133d67c881f363f0b5584ebd21a965eb3435aa1)

This patch is the follow-up for the commit
1672bdc0ffbee9f32fadb6943909d6af7eb9a7b1 ("x64: Fix __call metamethod
return dispatch."). This patch uses the incorrect macro x64 (which is
undefined in dasm) instead of X64. `KBASE` (r15d) is still compared
against `BASE` (edx) instead of `KBASEa` (r15) against rdx.

This patch fixes the typo, so the correct registers are chosen.

Sergey Kaplun:
* added the description for the problem

Part of tarantool/tarantool#9145
---

The test is omitted for the same reason as it was omitted in the 1672bdc
commit: it is too hard (or even impossible) to create the test case.

Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-1110-x64-return-dispatch
Tarantool PR: https://github.com/tarantool/tarantool/pull/9335
Relate issues and PRs:
* https://github.com/LuaJIT/LuaJIT/pull/636
* https://github.com/LuaJIT/LuaJIT/issues/1110
* https://github.com/tarantool/tarantool/issues/9145

 src/vm_x86.dasc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/vm_x86.dasc b/src/vm_x86.dasc
index 9fa9a3f7..6a353796 100644
--- a/src/vm_x86.dasc
+++ b/src/vm_x86.dasc
@@ -1451,7 +1451,7 @@ static void build_subroutines(BuildCtx *ctx)
   |  mov LFUNC:RB, [RA-8]
   |  add NARGS:RD, 1
   |  // This is fragile. L->base must not move, KBASE must always be defined.
-  |.if x64
+  |.if X64
   |  cmp KBASEa, rdx			// Continue with CALLT if flag set.
   |.else
   |  cmp KBASE, BASE			// Continue with CALLT if flag set.
-- 
2.42.0