[Tarantool-patches] [PATCH luajit] ARM64: Fix pcall() error case.

[Maxim Kokryashkin]

Hi, Sergey!
LGTM, except for a few nits regarding the commit message.
 
> 
>>From: Mike Pall <mike>
>>
>>Reported by Alex Orlenko.
>>
>>(cherry picked from commit b4b2dce9fc3ffaaaede39b36d06415311e2aa516)
>>
>>The `pcall()` assembler preambule modifies `RC` (`x28`) (N args * 8)
>The «`RC` (`x28`) (N args * 8)» expression is hard to percieve. I suggest
>reformulating it in a way like «modifies `RC`, which is mapped to `x28`, so
>it has value ...». Feel free to ignore.
>>during the check of the amount of the given arguments. So, this wrong
>>value using in the `fff_fallback` routine leading to a crash on the
>Typo: s/using/being used/
>Typo: s/leading/leads
>Typo: s/on the/on
>>error throwing, because the Lua stack is filled incorrect and can't be
>Typo: s/is filled incorrect/is incorrectly filled/
>>unwound.
>>
>>This patch adds the additional comparison before taking the fallback
>>branch and modifies `RC` only after this branch.
>>
>>Sergey Kaplun:
>>* added the description and the test for the problem
>>
>>Part of tarantool/tarantool#8069
>>---
>>
>>PR:  https://github.com/tarantool/tarantool/pull/8295
>>Branch:  https://github.com/tarantool/luajit/tree/skaplun/lj-762-arm64-pcall-no-arg
>>Issues:
>>*  https://github.com/tarantool/tarantool/issues/8069
>>*  https://github.com/LuaJIT/LuaJIT/issues/762
>>
>> src/vm_arm64.dasc | 3 ++-
>> test/tarantool-tests/lj-762-pcall-no-arg.test.lua | 15 +++++++++++++++
>> 2 files changed, 17 insertions(+), 1 deletion(-)
>> create mode 100644 test/tarantool-tests/lj-762-pcall-no-arg.test.lua
>>
>>diff --git a/src/vm_arm64.dasc b/src/vm_arm64.dasc
>>index f517a808..e8b63d33 100644
>>--- a/src/vm_arm64.dasc
>>+++ b/src/vm_arm64.dasc
>>@@ -1168,9 +1168,10 @@ static void build_subroutines(BuildCtx *ctx)
>>   |//-- Base library: catch errors ----------------------------------------
>>   |
>>   |.ffunc pcall
>>+ | cmp NARGS8:RC, #8
>>   | ldrb TMP0w, GL->hookmask
>>- | subs NARGS8:RC, NARGS8:RC, #8
>>   | blo ->fff_fallback
>>+ | sub NARGS8:RC, NARGS8:RC, #8
>>   | mov RB, BASE
>>   | add BASE, BASE, #16
>>   | ubfx TMP0w, TMP0w, #HOOK_ACTIVE_SHIFT, #1
>>diff --git a/test/tarantool-tests/lj-762-pcall-no-arg.test.lua b/test/tarantool-tests/lj-762-pcall-no-arg.test.lua
>>new file mode 100644
>>index 00000000..6cbfe707
>>--- /dev/null
>>+++ b/test/tarantool-tests/lj-762-pcall-no-arg.test.lua
>>@@ -0,0 +1,15 @@
>>+local tap = require('tap')
>>+
>>+-- Test file to check error raising for `pcall()` without
>>+-- arguments. Regardless that the problem is aarch64-specific,
>>+-- it is good to test it for all arches.
>>+-- See also  https://github.com/LuaJIT/LuaJIT/issues/762 .
>>+local test = tap.test('lj-762-pcall-no-arg')
>>+test:plan(2)
>>+
>>+local result, err = pcall(pcall)
>>+
>>+test:ok(not result, 'pcall() without args: bad status')
>>+test:like(err, 'value expected', 'pcall() without args: error message')
>>+
>>+os.exit(test:check() and 0 or 1)
>>--
>>2.34.1
>--
>Best regards,
>Maxim Kokryashkin
> 
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